- - See How to contribute to Poi. -
- -
- These are not necessarily deemed to be high enough quality to be included in the
- core distribution, but they have been tested under contrib/ directory.
-
- None as yet! - although you can expect that some of the links - listed below will eventually migrate to the "contributed components" level, and - then maybe even into the main distribution. -
-Submissions of modifications - to Poi which are awaiting review. Anyone can - comment on them on the dev mailing list - code reviewers are needed! - Use these at your own risk - although Poi has no guarantee - either, these patches have not been reviewed, let alone accepted. -
-The other extensions listed here are not endorsed by the Poi - project either - they are provided as a convenience only. They may or may not work, - they may or may not be open source, etc. -
- -To have a link added to this table, see How to contribute - to POI.
- -| Name and Link | -Type | -Description | -Status | -Licensing | -Contact | -
|---|
- A number of people are using POI for a variety of purposes. As with - any new API or technology, the first question people generally ask - is not "how can I" but rather "Who else is doing what I'm about to - do?" This is understandable with the abysmal success rate in the - software business. These case statements are meant to help create - confidence and understanding. -
-- We are actively seeking case studies for this page (after all it - just started). Andy Oliver (acoliver at apache dot org) has - agreed to have a few T-Shirts printed with the POI logo (once its - chosen) for the first - few best submissions. To submit a case study, either - - submit a patch for this page (preferred) or email it to the - mailing list - . -
-- The Bank of Lithuania - reports financial statistical data to Excel format using the - Jakarta POI - project's - HSSF API. The system is based on Oracle JServer and - utilizes a Java stored procedure that outputs to XLS format - using the HSSF API. - Arian Lashkov (alaskov at lbank.lt) -
--Bit Tracker (http://www.bittracker.com) is the world's first and only web-based drill bit tracking system to manage your company's critical bit information and use that data to its full potential. It manages all bit related data, including their usage, locations, how they were used, and results such as rate of penetration and dull grade after use. This data needs to be available in Excel format for backwards compatibility and other uses in the industry. After using CSV and HTML formats, we needed something better for creating the spreadsheets and POI is the answer. It works great and was easy to implement. Kudos to the POI team. -
-- Travis Reeder (travis at thinkvirtual dot com) -
-- Edwards and Kelcey Technology (http://www.ekcorp.com/) developed a - Facility - Managament and Maintenance System for the Telecommunications industry - based - on Turbine and Velocity. Originally the invoicing was done with a simple - CVS - sheet which was then marked up by accounts and customized for each client. - As growth has been consistent with the application, the requirement for - invoices that need not be touched by hand increased. POI provided the - solution to this issue, integrating easily and transparently into the - system. POI HSSF was used to create the invoices directly from the server - in - Excel 97 format and now services over 150 unique invoices per month. -
-- Cameron Riley (crileyNO@ SPAMekmail.com) -
-- ClickFind Inc. used the POI - projects HSSF API to provide their medical - research clients with an Excel export from their electronic data - collection web service Data Collector 3.0. The POI team's assistance - allowed ClickFind to give their clients a data format that requires less - technical expertise than the XML format used by the Data Collector - application. This was important to ClickFind as many of their current - and potential clients are already using Excel in their day-to-day - operations and in established procedures for handling their generated - clinical data. - Jared Walker (jared.walker at clickfind.com) -
-- The problem usually manifests itself as the junk characters being shown on - screen. The problem persists even though you have set the correct mime type. -
-- The short answer is, don't depend on IE to display a binary file type properly if you stream it via a - servlet. Every minor version of IE has different bugs on this issue. -
-- The problem in most versions of IE is that it does not use the mime type on - the HTTP response to determine the file type; rather it uses the file extension - on the request. Thus you might want to add a - .xls to your request - string. For example - http://yourserver.com/myServelet.xls?param1=xx. This is - easily accomplished through URL mapping in any servlet container. Sometimes - a request like - http://yourserver.com/myServelet?param1=xx&dummy=file.xls is also - known to work. - -
-- To guarantee opening the file properly in Excel from IE, write out your file to a - temporary file under your web root from your servelet. Then send an http response - to the browser to do a client side redirection to your temp file. (Note that using a - server side redirect using RequestDispatcher will not be effective in this case) -
-- Note also that when you request a document that is opened with an - external handler, IE sometimes makes two requests to the webserver. So if your - generating process is heavy, it makes sense to write out to a temporary file, so that multiple - requests happen for a static file. -
-- None of this is particular to Excel. The same problem arises when you try to - generate any binary file dynamically to an IE client. For example, if you generate - pdf files using - FOP, you will come across many of the same issues. - -
- -- Yes. You first need to get a HSSFDataFormat object from the workbook and call getFormat with the desired format. Some examples are here. -
-- Yes. This is a built-in format for excel that you can get from HSSFDataFormat object using the format string "@". Also, the string "text" will alias this format. -
-You just create the styles OUTSIDE of the loop in which you create cells.
-GOOD:
-BAD:
-- Branches are tagged in the following way: -
-- Merge points should be tagged as follows: -
-- Releases should be tagged as: -
-- Don't forget which branch you are currently on. This is critically - important. Committing stuff to the wrong branch causes all sorts of - headaches. Best to name your checkout after the branch you are on. -
-- All branching is currently managed by Glen Stampoultzis. If you wish - to create your own branch please let him know. Merging is also - handled by Glen. Just pop him a mail if you feel it's necessary to - create a branch or perform a merge. -
-- The reason to go through a single point for branching is that it can be - an easy thing to get wrong. Having a single person managing branches - means there is less chance of getting getting our wires crossed with this - difficult area of CVS. -
-- The following branches are currently active: -
-| - Branch - | -- Description - | -
|---|---|
| - HEAD - | -- This is the trunk and is always active. Currently it is being used to continue development - of the 2.0 release. - | -
| - REL_1_5_BRANCH - | -- All bug fixes not specifically relevant to the 2.0 work should be placed in this branch. - From here they will merged back to the trunk and the merge point marked. - | -
- Any information in here that might be perceived as legal information is - informational only. We're not lawyers, so consult a legal professional - if needed. -
-- The POI project is OpenSource - and developed/distributed under the - Apache Software License. Unlike other licenses this license allows - free open source development; however, it does not require you to release - your source or use any particular license for your source. If you wish - to contribute to POI (which you're very welcome and encouraged to do so) - then you must agree to release the rights of your source to us under this - license. -
-- In short, stay away, stay far far away. Implementing these file formats - in POI is done strictly by using public information. Public information - includes sources from other open source projects, books that state the - purpose intended is for allowing implementation of the file format and - do not require any non-disclosure agreement and just hard work. - We are intent on keeping it - legal, by contributing patches you agree to do the same. -
-- If you've ever received information regarding the OLE 2 Compound Document - Format under any type of exclusionary agreement from Microsoft, or - (probably illegally) received such information from a person bound by - such an agreement, you cannot participate in this project. (Sorry) -
-- Those submitting patches that show insight into the file format may be - asked to state explicitly that they are eligible or possibly sign an - agreement. -
-- Create patches by getting the latest sources from CVS (the HEAD). - Alter or add files as appropriate. Then, from the jakarta-poi directiory, - type cvs diff -u > mypatch.patch. This will capture all of your changes - in a patch file of the appropriate format. Next, if you've added any - files, create an archive (tar.bz2 preferred as its the smallest) in a - path-preserving archive format, relative to your jakarta-poi directory. - (Note: If you use WinCVS, move to - [Admin] -> [Command Line] Menu and type "cvs diff -u" at - [Enter a cvs line command] input field ([Commandline Settings] Tab), - while selecting the target directories or files, in order to create - unified diffs. - In other words, [Alt+A]+[Alt+C]+[Alt+C] and type "cvs diff -u".) - You'll attach both files in the next step. -
-- Patches are submitted via the Bug Database. - Create a new bug, set the subject to [PATCH] followed by a brief description. Explain you patch and any special instructions and submit/save it. - Next, go back to the bug, and create attachements for the patch files you - created. Be sure to describe not only the files purpose, but its format. - (Is that ZIP or a tgz or a bz2 or what?). -
-- Make sure your patches include the @author tag on any files you've altered - or created. Make sure you've documented your changes and altered the - examples/etc to reflect them. Any new additions should have unit tests. - Lastly, ensure that you've provided approriate javadoc. (see - Coding - Standards). Patches that are of low quality may be rejected or - the contributer may be asked to bring them up to spec. -
-The purpose of this document is to give a brief high level overview of the - HDF document format. This document does not go into in-depth technical - detail and is only meant as a supplement to the Microsoft Word 97 Binary - File Format freely available at Wotsit.org.
-The OLE file format is not discussed in this document. It is assumed that - the reader has a working knowledge of the POIFS API.
- -A Word file is made up of the document text and data structures - containing formatting information about the text. Of course, this is a - very simplified illustration. There are fields and macros and other - things that have not been considered. At this stage, HDF is mainly - concerned with formatted text.
-The entry point for HDF's reading of a Word file is the File Information - Block (FIB). This structure is the entry point for the locations and size - of a document's text and data structures. The FIB is located at the - beginning of the main stream.
-The document's text is also located in the main stream. Its starting - location is given as FIB.fcMin and its length is given in bytes by - FIB.ccpText. These two values are not very useful in getting the text - because of unicode. There may be unicode text intermingled with ASCII - text. That brings us to the piece table.
-The piece table is used to divide the text into non-unicode and unicode - pieces. The size and offset are given in FIB.fcClx and FIB.lcbClx - respectively. The piece table may contain Property Modifiers (prm). - These are for complex(fast-saved) files and are skipped. Each text piece - contains offsets in the main stream that contain text for that piece. - If the piece uses unicode, the file offset is masked with a certain bit. - Then you have to unmask the bit and divide by 2 to get the real file - offset.
-All text formatting is based on styles contained in the StyleSheet. - The StyleSheet is a data structure containing among other things, style - descriptions. Each style description can contain a paragraph style and - a character style or simply a character style. Each style description - is stored in a compressed version on file. Basically these are deltas - from another style.
-Eventually, you have to chain back to the nil style which is an - imaginary style with certain implied values.
-Paragraph and Character formatting properties for a document's text are - stored on file as deltas from some base style in the Stylesheet. The - deltas are used to create a complete uncompressed style in memory.
-Uncompressed paragraph styles are represented by the Pargraph - Properties(PAP) data structure. Uncompressed character styles are - represented by the Character Properties(CHP) data structure. The styles - for the document text are stored in compressed format in the - corresponding Formatted Disk Pages (FKP). A compressed PAP is referred - to as a PAPX and a compressed CHP is a CHPX. The FKP locations are - stored in the bin table. There are seperate bin tables for CHPXs and - PAPXs. The bin tables' locations and sizes are stored in the FIB.
-A FKP is a 512 byte OLE page. It contains the offsets of the beginning - and end of each paragraph/character run in the main stream and the - compressed properties for that interval. The compessed PAPX is based on - its base style in the StyleSheet. The compressed CHPX is based on the - enclosing paragraph's base style in the Stylesheet.
-All compressed properties(CHPX, PAPX, SEPX) contain a grpprl. A grpprl - is an array of sprms. A sprm defines a delta from some base property. - There is a table of possible sprms in the Word 97 spec. Each sprm is a - two byte operand followed by a parameter. The parameter size depends on - the sprm. Each sprm describes an operation that should be performed on - the base style. After every sprm in the grpprl is performed on the base - style you will have the style for the paragraph, character run, - section, etc.
-HDF is the name of OUR port of the Microsoft Word 97(-2002) file format to - pure Java.
-HDF is still in early development. It is in the - scratchpad section of the - CVS. Source code in the org.apache.poi.hdf.extractor tree is - legacy code. Source in the org.apache.poi.hdf.model - tree is the old legacy code refactored into an object model. Check the How-To - page for detailed examples on using HDF. -
-- We are looking for developers!!! If you are interested in helping with HDF - familiarize yourself with the source code and just start coding. Make sure - you read the guidelines for - getting involved
-The POI project was dreamed up back around April 2001, when - Andy Oliver landed a short term contract to do Java-based - reporting to Excel. He'd done this project a few times before - and knew right where to look for the tools he needed. - Ironically, the API he used to use had skyrocketed from around - $300 ($US) to around $10K ($US). He figured it would take two - people around six months to write an Excel port so he - recommended the client fork out the $10K. -
- -Around June 2001, Andy started thinking how great it would - be to have an open source Java tool to do this and, while he - had some spare time, he started on the project and learned - about OLE 2 Compound Document Format. After hitting some real - stumpers he realized he'd need help. He posted a message to - his local Java User's Group (JUG) and asked if anyone else - would be interested. He lucked out and the most talented Java - programmer he'd ever met, Marc Johnson, joined the project. He - ran rings around Andy at porting OLE 2 CDF and rewrote his - skeletal code into a more sophisticated library. It took Marc - a few iterations to get something they were happy with. -
- -While Marc worked on that, Andy ported XLS to Java, based - on Marc's library. Several users wrote in asking to read XLS - (not just write as had originally been planned) and one user - had special requests for a different use for POIFS. Before - long, the project scope had tripled. POI 1.0 was released a - month later than planned, but with far more features. Marc - quickly wrote the serializer framework and HSSF Serializer in - record time and Andy banged out more documentation and worked - on making people aware of the project -
- -Shortly before the release, POI was fortunate to come into - contact with Nicola -Ken- Barrozzi who gave them samples for - the HSSF Serializer and help uncover its unfortunate bugs - (which were promptly fixed). More recently, Ken ported most - of the POI project documentation to XML from Andy's crappy - HTML docs he wrote with Star Office. -
- -Around the same time as the release, Glen Stampoultzis -joined the project. Glen was ticked off at Andy's flippant attitude -towards adding graphing to HSSF. Glen got so ticked off he decided to -grab a hammer and do it himself. Glen has already become an integral -part of the POI development community; his contributions to HSSF have -already started making waves. -
- -Somewhere in there we decided to finally submit the project - to The Apache - Cocoon Project, only to discover the project had - outgrown fitting nicely into just Cocoon long ago. - Furthermore, Andy started eyeing other projects he'd like to - see POI functionality added to. So it was decided to donate - the Serializers and Generators to Cocoon, other POI - integration components to other projects, and the POI APIs - would become part of Jakarta. It was a bumpy road but it - looks like everything turned out since you're reading this! -
- -First we'll tackle this from a project standpoint: Well, we - made an offer to Microsoft and Actuate (tongue in cheek - ... well mostly) that we'd quit the project and retire if - they'd simply write us each a really large check. I've yet to - get a phone call or email so I'm assuming they're not going to - pay us to go away. -
-Next, we've got some work to do here at Jakarta to finish - integrating POI into the community. Furthermore, we're - still transitioning the Serializer to Cocoon. -
-HSSF, during the 2.0 cycle, will undergo a few - optimizations. We'll also be adding new features like a full - implementation of Formulas and custom text formats. We're - hoping to be able to generate smaller files by adding - write-support for RK, MulRK and MulBlank records. I'm also - going to work on a Cocoon 2 Generator. Currently, reading is - not very efficient in HSSF. This is mainly because in order to - write or modify, one needs to be able to update upstream - pointers to downstream data. To do this you have to have - everything between in memory. A Generator would allow SAX - events to be processed instead. (This will be based on the low - level structures). One of the great things about this is that, - you'll not only have a more efficient way to read the file, - you'll have a great way to use spreadsheets as XML data - sources. -
-The HSSF Serializer, will further separate into a general - framework for creating serializers for other formats and the - HSSF Serializer specific implementation. (This is largely - already true). We'll also be adding support for features - already supported by HSSF (styles, fonts, text formats). We're - hoping to add support for formulas during this cycle. -
-We're beginning to expand our scope yet again. If we could - do all of this for XLS files, what about Doc files or PPT - files? We're thinking that our next component (HDF - Horrible - Document Format) should follow the same pattern. We're hoping - that new blood will join the team and allow us to tackle this - even faster (in part because POIFS is already finished). But - maybe what we need most is you!
-This HOW-TO is organized in three sections. You should read them - sequentially because the later sections build upon the earlier ones.
- -The first section explains how to read - the most important standard properties of a Microsoft Office - document. Standard properties are things like title, author, creation - date etc. It is quite likely that you will find here what you need and - don't have to read the other sections.
-The second section goes a small step - further and focusses on reading additional standard properties. It also - talks about exceptions that may be thrown when dealing with HPSF and - shows how you can read properties of embedded objects.
-The third section tells how to read - non-standard properties. Non-standard properties are application-specific - triples consisting of an ID, a type, and a value.
-The first thing you should understand is that properties are stored in - separate documents inside the POI filesystem. (If you don't know what a - POI filesystem is, read the POIFS - documentation.) A document in a POI filesystem is also called a - stream.
- -The following example shows how to read a POI filesystem's
- "title" property. Reading other properties is similar. Consider the API
- documentation of org.apache.poi.hpsf.SummaryInformation to
- learn which methods are available!
The standard properties this section focusses on can be found in a - document called \005SummaryInformation located in the root of the - POI filesystem. The notation \005 in the document's name means - the character with the decimal value of 5. In order to read the title, an - application has to perform the following steps:
- -Open the document \005SummaryInformation located in the root - of the POI filesystem.
-Create an instance of the class SummaryInformation from
- that document.
Call the SummaryInformation instance's
- getTitle() method.
Sounds easy, doesn't it? Here are the steps in detail.
- - -An application that wants to open a document in a POI filesystem - (POIFS) proceeds as shown by the following code fragment. (The full - source code of the sample application is available in the - examples section of the POI source tree as - ReadTitle.java.
- -The first interesting statement is
- -It creates a
- org.apache.poi.poifs.eventfilesystem.POIFSReader instance
- which we shall need to read the POI filesystem. Before the application
- actually opens the POI filesystem we have to tell the
- POIFSReader which documents we are interested in. In this
- case the application should do something with the document
- \005SummaryInformation.
This method call registers a
- org.apache.poi.poifs.eventfilesystem.POIFSReaderListener
- with the POIFSReader. The POIFSReaderListener
- interface specifies the method processPOIFSReaderEvent
- which processes a document. The class
- MyPOIFSReaderListener implements the
- POIFSReaderListener and thus the
- processPOIFSReaderEvent method. The eventing POI filesystem
- calls this method when it finds the \005SummaryInformation
- document. In the sample application MyPOIFSReaderListener is
- a static class in the ReadTitle.java source file.
Now everything is prepared and reading the POI filesystem can - start:
- -The following source code fragment shows the
- MyPOIFSReaderListener class and how it retrieves the
- title.
The line
- -declares a SummaryInformation variable and initializes it
- with null. We need an instance of this class to access the
- title. The instance is created in a try block:
The expression event.getStream() returns the input stream
- containing the bytes of the property set stream named
- \005SummaryInformation. This stream is passed into the
- create method of the factory class
- org.apache.poi.hpsf.PropertySetFactory which returns
- a org.apache.poi.hpsf.PropertySet instance. It is more or
- less safe to cast this result to SummaryInformation, a
- convenience class with methods like getTitle(),
- getAuthor() etc.
The PropertySetFactory.create method may throw all sorts
- of exceptions. We'll deal with them in the next sections. For now we just
- catch all exceptions and throw a RuntimeException
- containing the message text of the origin exception.
If all goes well, the sample application retrieves the title and prints - it to the standard output. As you can see you must be prepared for the - case that the POI filesystem does not have a title.
- -Please note that a Microsoft Office document does not necessarily
- contain the \005SummaryInformation stream. The documents created
- by the Microsoft Office suite have one, as far as I know. However, an
- Excel spreadsheet exported from StarOffice 5.2 won't have a
- \005SummaryInformation stream. In this case the applications
- won't throw an exception but simply does not call the
- processPOIFSReaderEvent method. You have been warned!
A couple of additional standard properties are not - contained in the \005SummaryInformation stream explained above, - for example a document's category or the number of multimedia clips in a - PowerPoint presentation. Microsoft has invented an additional stream named - \005DocumentSummaryInformation to hold these properties. With two - minor exceptions you can proceed exactly as described above to read the - properties stored in \005DocumentSummaryInformation:
- -Instead of \005SummaryInformation use - \005DocumentSummaryInformation as the stream's name.
Replace all occurrences of the class
- SummaryInformation by
- DocumentSummaryInformation.
And of course you cannot call getTitle() because
- DocumentSummaryInformation has different query methods. See
- the Javadoc API documentation for the details!
In the previous section the application simply caught all - exceptions and was in no way interested in any - details. However, a real application will likely want to know what went - wrong and act appropriately. Besides any IO exceptions there are three - HPSF resp. POI specific exceptions you should know about:
- -NoPropertySetStreamException:This exception is thrown if the application tries to create a
- PropertySet instance from a stream that is not a
- property set stream. (SummaryInformation and
- DocumentSummaryInformation are subclasses of
- PropertySet.) A faulty property set stream counts as not
- being a property set stream at all. An application should be prepared to
- deal with this case even if it opens streams named
- \005SummaryInformation or
- \005DocumentSummaryInformation only. These are just names. A
- stream's name by itself does not ensure that the stream contains the
- expected contents and that this contents is correct.
UnexpectedPropertySetTypeExceptionThis exception is thrown if a certain type of property set is
- expected somewhere (e.g. a SummaryInformation or
- DocumentSummaryInformation) but the provided property
- set is not of that type.
MarkUnsupportedExceptionThis exception is thrown if an input stream that is to be parsed
- into a property set does not support the
- InputStream.mark(int) operation. The POI filesystem uses
- the DocumentInputStream class which does support this
- operation, so you are safe here. However, if you read a property set
- stream from another kind of input stream things may be
- different.
Many Microsoft Office documents contain embedded
- objects, for example an Excel sheet on a page in a Word
- document. Embedded objects may have property sets of their own. An
- application can open these property set streams as described above. The
- only difference is that they are not located in the POI filesystem's root
- but in a nested directory instead. Just register a
- POIFSReaderListener for the property set streams you are
- interested in. For example, the POIBrowser application in the
- contrib section tries to open each and every document in a POI filesystem
- as a property set stream. If this operation was successful it displays the
- properties.
Now comes the real hardcode stuff. As mentioned above,
- SummaryInformation and
- DocumentSummaryInformation are just special cases of the
- general concept of a property set. This concept says that a
- property set consists of properties and that each
- property is an entity with an ID, a
- type, and a value.
Okay, that was still rather easy. However, to make things more - complicated, Microsoft in its infinite wisdom decided that a property set - shalt be broken into one or more sections. Each section - holds a bunch of properties. But since that's still not complicated - enough, a section may have an optional dictionary that - maps property IDs to property names - we'll explain - later what that means.
- -The procedure to get to the properties is the following:
- -PropertySetFactory class to
- create a PropertySet object from a property set stream. If
- you don't know whether an input stream is a property set stream, just
- try to call PropertySetFactory.create(java.io.InputStream):
- You'll either get a PropertySet instance returned or an
- exception is thrown.PropertySet's method getSections()
- to get the sections contained in the property set. Each section is
- an instance of the Section class.F29F85E0-4FF9-1068-AB-91-08-00-2B-27-B3-D9. You can
- get the format ID with Section.getFormatID().Section can be retrieved
- with Section.getProperties(). The result is an array of
- Property instances.Property
- class has methods to retrieve them.Let's have a look at a sample Java application that dumps all property - set streams contained in a POI file system. The full source code of this - program can be found as ReadCustomPropertySets.java in the - examples area of the POI source code tree. Here are the key - sections:
- -The most important package the application needs is
- org.apache.poi.hpsf.*. This package contains the HPSF
- classes. Most classes named below are from the HPSF package. Of course we
- also need the POIFS event file system's classes and java.io.*
- since we are dealing with POI I/O. From the java.util package
- we use the List and Iterator class. The class
- org.apache.poi.util.HexDump provides a methods to dump byte
- arrays as nicely formatted strings.
The POIFSReader is set up in a way that the listener
- MyPOIFSReaderListener is called on every file in the POI file
- system.
The listener class tries to create a PropertySet from each
- stream using the PropertySetFactory.create() method:
Creating the PropertySet is done in a try
- block, because not each stream in the POI file system contains a property
- set. If it is some other file, the
- PropertySetFactory.create() throws a
- NoPropertySetStreamException, which is caught and
- logged. Then the program continues with the next stream. However, all
- other types of exceptions cause the program to terminate by throwing a
- runtime exception. If all went well, we can print the name of the property
- set stream.
The next step is to print the number of sections followed by the - sections themselves:
- -The PropertySet's method getSectionCount()
- returns the number of sections.
To retrieve the sections, use the getSections()
- method. This method returns a java.util.List containing
- instances of the Section class in their proper order.
The sample code shows a loop that retrieves the Section
- objects one by one and prints some information about each one. Here is
- the complete body of the loop:
The first method called on the Section instance is
- getFormatID(). As explained above, the format ID of the
- first section in a property set determines the type of the property
- set. Its type is ClassID which is essentially a sequence of
- 16 bytes. A real application using its own type of a custom property set
- should have defined a unique format ID and, when reading a property set
- stream, should check the format ID is equal to that unique format ID. The
- sample program just prints the format ID it finds in a section:
As you can see, the getFormatID() method returns a
- ClassID object. An array containing the bytes can be
- retrieved with ClassID.getBytes(). In order to get a nicely
- formatted printout, the sample program uses the hex() helper
- method which in turn uses the POI utility class HexDump in
- the org.apache.poi.util package. Another helper method is
- out() which just saves typing
- System.out.println().
Before getting the properties, it is possible to find out how many
- properties are available in the section via the
- Section.getPropertyCount(). The sample application uses this
- method to print the number of properties to the standard output:
Now its time to get to the properties themselves. You can retrieve a
- section's properties with the method
- Section.getProperties():
As you can see the result is an array of Property
- objects. This class has three methods to retrieve a property's ID, its
- type, and its value. The following code snippet shows how to call
- them:
The output of the sample program might look like the following. It
- shows the summary information and the document summary information
- property sets of a Microsoft Word document. However, unlike the first and
- second section of this HOW-TO the application does not have any code
- which is specific to the SummaryInformation and
- DocumentSummaryInformation classes.
There are some interesting items to note:
- -Properties in the same section are distinguished by their IDs. This is - similar to variables in a programming language like Java, which are - distinguished by their names. But unlike variable names, property IDs are - simple integral numbers. There is another similarity, however. Just like - a Java variable has a certain scope (e.g. a member variables in a class), - a property ID also has its scope of validity: the section.
- -Two property IDs in sections with different section format IDs - don't have the same meaning even though their IDs might be equal. For - example, ID 4 in the first (and only) section of a summary - information property set denotes the document's author, while ID 4 in the - first section of the document summary information property set means the - document's byte count. The sample output above does not show a property - with an ID of 4 in the first section of the document summary information - property set. That means that the document does not have a byte - count. However, there is a property with an ID of 4 in the - second section: This is a user-defined property ID - we'll get - to that topic in a minute.
- -So, how can you find out what the meaning of a certain property ID in
- the summary information and the document summary information property set
- is? The standard property sets as such don't have any hints about the
- meanings of their property IDs. For example, the summary
- information property set does not tell you that the property ID 4 stands
- for the document's author. This is external knowledge. Microsoft defined
- standard meanings for some of the property IDs in the summary information
- and the document summary information property sets. As a help to the Java
- and POI programmer, the class PropertyIDMap in the
- org.apache.poi.hpsf.wellknown package defines constants
- for the "well-known" property IDs. For example, there is the
- definition
These definitions allow you to use symbolic names instead of - numbers.
- -In order to provide support for the other way, too, - i.e. to map
- property IDs to property names - the class PropertyIDMap
- defines two static methods:
- getSummaryInformationProperties() and
- getDocumentSummaryInformationProperties(). Both return
- java.util.Map objects which map property IDs to
- strings. Such a string gives a hint about the property's meaning. For
- example,
- PropertyIDMap.getSummaryInformationProperties().get(4)
- returns the string "PID_AUTHOR". An application could use this string as
- a key to a localized string which is displayed to the user, e.g. "Author"
- in English or "Verfasser" in German. HPSF might provide such
- language-dependend ("localized") mappings in a later release.
Usually you won't have to deal with those two maps. Instead you should
- call the Section.getPIDString(int) method. It returns the
- string associated with the specified property ID in the context of the
- Section object.
Above you learned that property IDs have a meaning in the scope of a - section only. However, there are two exceptions to the rule: The property - IDs 0 and 1 have a fixed meaning in all sections:
- -| Property ID | -Meaning | -
|---|---|
| 0 | -The property's value is a dictionary, i.e. a - mapping from property IDs to strings. | -
| 1 | -The property's value is the number of a codepage, - i.e. a mapping from character codes to characters. All strings in the - section containing this property must be interpreted using this - codepage. Typical property values are 1252 (8-bit "western" characters) - or 1200 (16-bit Unicode characters). | -
A property is nothing without its value. It is stored in a property set
- stream as a sequence of bytes. You must know the property's
- type in order to properly interpret those bytes and
- reasonably handle the value. A property's type is one of the so-called
- Microsoft-defined "variant types". When you call
- Property.getType() you'll get a long value
- which denoting the property's variant type. The class
- Variant in the org.apache.poi.hpsf package
- holds most of those long values as named constants. For
- example, the constant VT_I4 = 3 means a signed integer value
- of four bytes. Examples of other types are VT_LPSTR = 30
- meaning a null-terminated string of 8-bit characters, VT_LPWSTR =
- 31 which means a null-terminated Unicode string, or VT_BOOL
- = 11 denoting a boolean value.
In most cases you won't need a property's type because HPSF does all - the work for you.
-When an application wants to retrieve a property's value and calls
- Property.getValue(), HPSF has to interpret the bytes making
- out the value according to the property's type. The type determines how
- many bytes the value consists of and what
- to do with them. For example, if the type is VT_I4, HPSF
- knows that the value is four bytes long and that these bytes
- comprise a signed integer value in the little-endian format. This is
- quite different from e.g. a type of VT_LPWSTR. In this case
- HPSF has to scan the value bytes for a Unicode null character and collect
- everything from the beginning to that null character as a Unicode
- string.
The good new is that HPSF does another job for you, too: It maps the - variant type to an adequate Java type.
- -| Variant type: | -Java type: | -
|---|---|
| VT_I2 | -java.lang.Integer | -
| VT_I4 | -java.lang.Long | -
| VT_FILETIME | -java.util.Date | -
| VT_LPSTR | -java.lang.String | -
| VT_LPWSTR | -java.lang.String | -
| VT_CF | -byte[] | -
| VT_BOOL | -java.lang.Boolean | -
The bad news is that there are still a couple of variant types HPSF - does not yet support. If it encounters one of these types it - returns the property's value as a byte array and leaves it to be - interpreted by the application.
- -An application retrieves a property's value by calling the
- Property.getValue() method. This method's return type is the
- abstract Object class. The getValue() method
- looks up the property's variant type, reads the property's value bytes,
- creates an instance of an adequate Java type, assigns it the property's
- value and returns it. Primitive types like int or
- long will be returned as the corresponding class,
- e.g. Integer or Long.
The property with ID 0 has a very special meaning: It is a - dictionary mapping property IDs to property names. We - have seen already that the meanings of standard properties in the - summary information and the document summary information property sets - have been defined by Microsoft. The advantage is that the labels of - properties like "Author" or "Title" don't have to be stored in the - property set. However, a user can define custom fields in, say, Microsoft - Word. For each field the user has to specify a name, a type, and a - value.
- -The names of the custom-defined fields (i.e. the property names) are - stored in the document summary information second section's - dictionary. The dictionary is a map which associates - property IDs with property names.
- -The method Section.getPIDString(int) not only returns with
- the well-known property names of the summary information and document
- summary information property sets, but with self-defined properties,
- too. It should also work with self-defined properties in self-defined
- sections.
The property with ID 1 holds the number of the codepage which was used - to encode the strings in this section. The present HPSF codepage support - is still very limited: When reading property value strings, HPSF - distinguishes between 16-bit characters and 8-bit characters. 16-bit - characters should be Unicode characters and thus be okay. 8-bit - characters are interpreted according to the platform's default character - set. This is fine as long as the document being read has been written on - a platform with the same default character set. However, if you receive a - document from another region of the world and want to process it with - HPSF you are in trouble - unless the creator used Unicode, of course.
-There are still some aspects of HSPF left which are not covered by this - HOW-TO. You should dig into the Javadoc API documentation to learn - further details. Since you've struggled through this document up to this - point, you are well prepared.
-Microsoft applications like "Word", "Excel" or "Powerpoint" let the user - describe his document by properties like "title", "category" and so on. The - application itself adds further information: last author, creation date - etc. These document properties are stored in so-called property set - streams. A property set stream is a separate document within a - POI filesystem. We'll call property - set streams mostly just "property sets". HPSF is POI's pure-Java - implementation to read (and in future to write) property sets.
- -The HPSF HOWTO describes what a Java - application should do to read a property set using HPSF and to retrieve the - information it needs.
- -HPSF supports OLE2 property set streams in general, and is not limited to - the special case of document properties in the Microsoft Office files - mentioned above. The HPSF description - describes the internal structure of property set streams. A separate - document explains the internal of thumbnail - images.
-A Microsoft Office document is internally organized like a filesystem
- with directory and files. Microsoft calls these files
- streams. A document can have properties attached to it,
- like author, title, number of words etc. These metadata are not stored in
- the main stream of, say, a Word document, but instead in a dedicated
- stream with a special format. Usually this stream's name is
- \005SummaryInformation, where \005 represents
- the character with a decimal value of 5.
A single piece of information in the stream is called a - property, for example the document title. Each property - has an integral ID (e.g. 2 for title), a - type (telling that the title is a string of bytes) and a - value (what this is should be obvious). A stream - containing properties is called a - property set stream.
- -This document describes the internal structure of a property set stream, - i.e. the Horrible Property Set Format (HDF). It does not - describe how a Microsoft Office document is organized internally and how - to retrieve a stream from it. See the POIFS documentation for that kind of - stuff.
- -The Horrible Property Set Format is not only used in the Summary
- Information stream in the top-level document of a Microsoft Office
- document. Often there is also a property set stream named
- \005DocumentSummaryInformation with additional properties.
- Embedded documents may have their own property set streams. You cannot
- tell by a stream's name whether it is a property set stream or not.
- Instead you have to open the stream and look at its bytes.
Before delving into the details of the property set stream format we - have to have a short look at data types. Integral values are stored in the - so-called little endian format. In this format the bytes - that make out an integral value are stored in the "wrong" order. For - example, the decimal value 4660 is 0x1234 in the hexadecimal notation. If - you think this should be represented by a byte 0x12 followed by another - byte 0x34, you are right. This is called the big endian - format. In the little endian format, however, this order is reversed and - the low-value byte comes first: 0x3412. -
- -The following table gives an overview about some important data - types:
- -|
- Name - |
-
- Length - |
-
- Example (Little Endian) - |
-
- Example (Big Endian) - |
-
|---|---|---|---|
Bytes |
-
- 1 byte - |
-
|
-
|
-
Word |
-
- 2 bytes - |
-
|
-
|
-
DWord |
-
- 4 bytes - |
-
|
-
|
-
|
- ClassID -A sequence of one DWord, two Words and eight Bytes - |
-
-
- 16 bytes - |
-
-
-
|
-
-
-
|
-
| - | - |
- The ClassID examples are given here in two different notations. The - second notation without the "0x" at the beginning and with dashes - inside shows the internal grouping into one DWord, two Words and eight - Bytes. - |
-
- Watch out: Microsoft documentation and tools show class IDs
- a little bit differently like
- |
-
A property set stream consists of three main parts:
- -The header and
-the section(s) containing the properties.
-The first bytes in a property set stream is the header. - It has a fixed length and looks like this:
- -|
- Offset - |
-
- Type - |
-
- Contents - |
-
- Remarks - |
-
|---|---|---|---|
|
- 0 - |
-
- Word - |
-
|
-
- If the first four bytes of a stream do not contain these values, the - stream is not a property set stream. - |
-
|
- 2 - |
-
- Word - |
-
|
- - |
|
- 4 - |
-
- DWord - |
-
- Denotes the operating system and the OS version under which this
- stream was created. The operating system ID is in the DWord's higher
- word (after little endian decoding): |
- - |
|
- 8 - |
-
- ClassID - |
-
|
-
- Most property set streams have this value but this is not - required. - |
-
|
- 24 - |
-
- DWord - |
-
-
|
-
- Section count. This field's value should be equal to 1 or greater. - Microsoft claims that this is a "reserved" field, but it seems to tell - how many sections (see below) are following in the stream. This would - really make sense because otherwise you could not know where and how - far you should read section data. - |
-
Following the header is the section list. This is an array of pairs each - consisting of a section format ID and an offset. This array has as many - pairs of ClassID and and DWord fields as the section count field in the - header says. The Summary Information stream contains a single section, the - Document Summary Information stream contains two.
- -|
- Type - |
-
- Contents - |
-
- Remarks - |
-
|---|---|---|
|
- ClassID - |
-
- Section format ID - |
-
-
|
-
|
- DWord - |
-
- Offset - |
-
- The number of bytes between the beginning of the stream and the - beginning of the section within the stream. - |
-
|
- ClassID - |
-
- Section format ID - |
-
- ... - |
-
|
- DWord - |
-
- Offset - |
-
- ... - |
-
|
- ... - |
-
- ... - |
-
- ... - |
-
A section is divided into three parts: the section header (with the - section length and the number of properties in the section), the - properties list (with type and offset of each property), and the - properties themselves. Here are the details:
- -|
- - |
-
- Type - |
-
- Contents - |
-
- Remarks - |
-
|---|---|---|---|
|
- Section header - |
-
-
- DWord - |
-
- Length - |
-
- The length of the section in bytes. - |
-
| - |
- DWord - |
-
- Property count - |
-
- The number of properties in the section. - |
-
|
- Properties list - |
-
-
- DWord - |
-
- Property ID - |
-
- The property ID tells what the property means. For example, an ID of
- |
-
| - |
- DWord - |
-
- Offset - |
-
- The number of bytes between the beginning of the section and the - property. - |
-
| - |
- ... - |
-
- ... - |
-
- ... - |
-
|
- Properties - |
-
-
- DWord - |
-
- Property type ("variant") - |
-
- This is the property's data type, e.g. an integer value, a byte - string or a Unicode string. See the - Property Types chapter for - details! - |
-
| - | Field length depends on the property type - ("variant") |
-
- Property value - |
-
- This field's length depends on the property's type. These are the - bytes that make out the DWord, the byte string or some other data of - fixed or variable length. - -The property value's length is always stored in an area which is a
- multiple of 4 in length. If the property is shorter, e.g. a byte
- string of 13 bytes, the remaining bytes are padded with |
-
| - |
- ... - |
-
- ... - |
-
- ... - |
-
As seen above, a section holds a property list: an array with property - IDs and offsets. The property ID gives each property a meaning. For - example, in the Summary Information stream the property ID 2 says that - this property is the document's title.
- -If you want to know a property ID's meaning, it is not sufficient to - know the ID itself. You must also know the - section format ID. For example, in the Document Summary - Information stream the property ID 2 means not the document's title but - its category. Due to Microsoft's infinite wisdom the section format ID is - not part of the section. Thus if you have only a section without the - stream it is in, you cannot make any sense of the properties because you - do not know what they mean.
- -So each section format ID has its own name space of property IDs. - Microsoft defined some "well-known" property IDs for the Summary - Information and the Document Summary Information streams. You can extend - them by your own additional IDs. This will be described below.
- -The Summary Information stream has a single section with a section
- format ID of 0xF29F85E04FF91068AB9108002B27B3D9. The following
- table defines the meaning of its property IDs. Each row associates a
- property ID with a name and an ID string. (The property
- type is just for informational purposes given here. As we have
- seen above, the type is always given along with the value.)
The property name is a readable string which could be - displayed to the user. However, this string is useful only for users who - understand English. The property name does not help with other - languages.
- -The property ID string is about the same but looks more - technically and is nothing a user should bother with. You could the ID - string and map it to an appropriate display string in a particular - language. Of course you could do that with the property ID as well and - with less overhead, but people (including software developers) tend to be - better in remembering symbolic constants than remembering numbers.
- -Property ID |
- Property Name |
- Property ID String |
- Property Type |
-
|---|---|---|---|
2 |
- Title |
- PID_TITLE |
- VT_LPSTR |
-
3 |
- Subject |
- PID_SUBJECT |
- VT_LPSTR |
-
4 |
- Author |
- PID_AUTHOR |
- VT_LPSTR |
-
5 |
- Keywords |
- PID_KEYWORDS |
- VT_LPSTR |
-
6 |
- Comments |
- PID_COMMENTS |
- VT_LPSTR |
-
7 |
- Template |
- PID_TEMPLATE |
- VT_LPSTR |
-
8 |
- Last Saved By |
- PID_LASTAUTHOR |
- VT_LPSTR |
-
9 |
- Revision Number |
- PID_REVNUMBER |
- VT_LPSTR |
-
10 |
- Total Editing Time |
- PID_EDITTIME |
- VT_FILETIME |
-
11 |
- Last Printed |
- PID_LASTPRINTED |
- VT_FILETIME |
-
12 |
- Create Time/Date |
- PID_CREATE_DTM |
- VT_FILETIME |
-
13 |
- Last Saved Time/Date |
- PID_LASTSAVE_DTM |
- VT_FILETIME |
-
14 |
- Number of Pages |
- PID_PAGECOUNT |
- VT_I4 |
-
15 |
- Number of Words |
- PID_WORDCOUNT |
- VT_I4 |
-
16 |
- Number of Characters |
- PID_CHARCOUNT |
- VT_I4 |
-
17 |
- Thumbnail |
- PID_THUMBNAIL |
- VT_CF |
-
18 |
- Name of Creating Application |
- PID_APPNAME |
- VT_LPSTR |
-
19 |
- Security |
- PID_SECURITY |
- VT_I4 |
-
The Document Summary Information stream has two sections with a section
- format ID of 0xD5CDD5022E9C101B939708002B2CF9AE for the first
- one. The following table defines the meaning of the property IDs in the
- first section. See the preceeding section for interpreting the table.
Property ID |
- Property name |
- Property ID string |
- VT type |
-
|---|---|---|---|
0 |
- Dictionary |
- PID_DICTIONARY |
- [Special format] |
-
1 |
- Code page |
- PID_CODEPAGE |
- VT_I2 |
-
2 |
- Category |
- PID_CATEGORY |
- VT_LPSTR |
-
3 |
- PresentationTarget |
- PID_PRESFORMAT |
- VT_LPSTR |
-
4 |
- Bytes |
- PID_BYTECOUNT |
- VT_I4 |
-
5 |
- Lines |
- PID_LINECOUNT |
- VT_I4 |
-
6 |
- Paragraphs |
- PID_PARCOUNT |
- VT_I4 |
-
7 |
- Slides |
- PID_SLIDECOUNT |
- VT_I4 |
-
8 |
- Notes |
- PID_NOTECOUNT |
- VT_I4 |
-
9 |
- HiddenSlides |
- PID_HIDDENCOUNT |
- VT_I4 |
-
10 |
- MMClips |
- PID_MMCLIPCOUNT |
- VT_I4 |
-
11 |
- ScaleCrop |
- PID_SCALE |
- VT_BOOL |
-
12 |
- HeadingPairs |
- PID_HEADINGPAIR |
- VT_VARIANT | VT_VECTOR |
-
13 |
- TitlesofParts |
- PID_DOCPARTS |
- VT_LPSTR | VT_VECTOR |
-
14 |
- Manager |
- PID_MANAGER |
- VT_LPSTR |
-
15 |
- Company |
- PID_COMPANY |
- VT_LPSTR |
-
16 |
- LinksUpTo Date |
- PID_LINKSDIRTY |
- VT_BOOL |
-
A property consists of a DWord type field followed by the - property value. The property type is an integer value and tells how the - data byte following it are to be interpreted. In the Microsoft world it is - also known as the variant.
- -The Usage column says where a variant type may occur. Not all - of them are allowed in a property set but just those marked with a [P]. - [V] - may appear in a VARIANT, [T] - may - appear in a TYPEDESC, [P] - may appear in an OLE property - set, [S] - may appear in a Safe Array.
- -Variant ID |
- Variant Type |
- Usage |
- Description |
-
|---|---|---|---|
0 |
- VT_EMPTY |
- [V] [P] |
- nothing |
-
1 |
- VT_NULL |
- [V] [P] |
- SQL style Null |
-
2 |
- VT_I2 |
- [V] [T] [P] [S] |
- 2 byte signed int |
-
3 |
- VT_I4 |
- [V] [T] [P] [S] |
- 4 byte signed int |
-
4 |
- VT_R4 |
- [V] [T] [P] [S] |
- 4 byte real |
-
5 |
- VT_R8 |
- [V] [T] [P] [S] |
- 8 byte real |
-
6 |
- VT_CY |
- [V] [T] [P] [S] |
- currency |
-
7 |
- VT_DATE |
- [V] [T] [P] [S] |
- date |
-
8 |
- VT_BSTR |
- [V] [T] [P] [S] |
- OLE Automation string |
-
9 |
- VT_DISPATCH |
- [V] [T] [P] [S] |
- IDispatch * |
-
10 |
- VT_ERROR |
- [V] [T] [S] |
- SCODE |
-
11 |
- VT_BOOL |
- [V] [T] [P] [S] |
- True=-1, False=0 |
-
12 |
- VT_VARIANT |
- [V] [T] [P] [S] |
- VARIANT * |
-
13 |
- VT_UNKNOWN |
- [V] [T] [S] |
- IUnknown * |
-
14 |
- VT_DECIMAL |
- [V] [T] [S] |
- 16 byte fixed point |
-
16 |
- VT_I1 |
- [T] |
- signed char |
-
17 |
- VT_UI1 |
- [V] [T] [P] [S] |
- unsigned char |
-
18 |
- VT_UI2 |
- [T] [P] |
- unsigned short |
-
19 |
- VT_UI4 |
- [T] [P] |
- unsigned short |
-
20 |
- VT_I8 |
- [T] [P] |
- signed 64-bit int |
-
21 |
- VT_UI8 |
- [T] [P] |
- unsigned 64-bit int |
-
22 |
- VT_INT |
- [T] |
- signed machine int |
-
23 |
- VT_UINT |
- [T] |
- unsigned machine int |
-
24 |
- VT_VOID |
- [T] |
- C style void |
-
25 |
- VT_HRESULT |
- [T] |
- Standard return type |
-
26 |
- VT_PTR |
- [T] |
- pointer type |
-
27 |
- VT_SAFEARRAY |
- [T] |
- (use VT_ARRAY in VARIANT) |
-
28 |
- VT_CARRAY |
- [T] |
- C style array |
-
29 |
- VT_USERDEFINED |
- [T] |
- user defined type |
-
30 |
- VT_LPSTR |
- [T] [P] |
- null terminated string |
-
31 |
- VT_LPWSTR |
- [T] [P] |
- wide null terminated string |
-
64 |
- VT_FILETIME |
- [P] |
- FILETIME |
-
65 |
- VT_BLOB |
- [P] |
- Length prefixed bytes |
-
66 |
- VT_STREAM |
- [P] |
- Name of the stream follows |
-
67 |
- VT_STORAGE |
- [P] |
- Name of the storage follows |
-
68 |
- VT_STREAMED_OBJECT |
- [P] |
- Stream contains an object |
-
69 |
- VT_STORED_OBJECT |
- [P] |
- Storage contains an object |
-
70 |
- VT_BLOB_OBJECT |
- [P] |
- Blob contains an object |
-
71 |
- VT_CF |
- [P] |
- Clipboard format |
-
72 |
- VT_CLSID |
- [P] |
- A Class ID |
-
0x1000 |
- VT_VECTOR |
- [P] |
- simple counted array |
-
0x2000 |
- VT_ARRAY |
- [V] |
- SAFEARRAY* |
-
0x4000 |
- VT_BYREF |
- [V] |
- void* for local use |
-
0x8000 |
- VT_RESERVED |
- ||
0xFFFF |
- VT_ILLEGAL |
- ||
0xFFF |
- VT_ILLEGALMASKED |
- ||
0xFFF |
- VT_TYPEMASK |
-
In order to assemble the HPSF description I used information publically - available on the Internet only. The references given below have been very - helpful. If you have any amendments or corrections, please let us know! - Thank you!
- -In - Understanding OLE - documents, Ken Kyler gives an introduction to OLE2 - documents - and especially to property sets. He names the property names, types, and - IDs of the Summary Information and Document Summary Information - stream.
-The - ActiveX Programmer's - Reference at - http://www.dwam.net/docs/oleref/ - seems a little outdated, but that's what I have found.
-An overview of the VT_ types is in
- Variant
- Type Definitions.
What is a FILETIME? The answer can be found
- under , http://www.vbapi.com/ref/f/filetime.html or
- http://www.cs.rpi.edu/courses/fall01/os/FILETIME.html.
- In short: The FILETIME structure holds a date and time associated
- with a file. The structure identifies a 64-bit integer specifying the
- number of 100-nanosecond intervals which have passed since January 1,
- 1601. This 64-bit value is split into the two dwords stored in the
- structure.
Information about the code page property in the - DocumentSummaryInformation stream is available at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/stg/stg/property_id_1.asp.
-This documentation origins from the HPSF description available at http://www.rainer-klute.de/~klute/Software/poibrowser/doc/HPSF-Description.html.
-Thumbnail information is stored as a VT_CF, or Thumbnail Variant. The - Thumbnail Variant is used to store various types of information in a - clipboard. The VT_CF can store information in formats for the Macintosh or - Windows clipboard.
- -There are many types of data that can be copied to the clipboard, but the - only types of information needed for thumbnail manipulation are the image - formats.
- -The VT_CF structure looks like this:
| Element: | -Clipboard Size | -Clipboard Format Tag | -Clipboard Data | -
|---|---|---|---|
| Size: | -32 bit unsigned integer (DWord) | -32 bit signed integer (DWord) | -variable length (byte array) | -
The Clipboard Size refers to the size (in bytes) of Clipboard Data - (variable size) plus the Clipboard Format (four bytes).
- -Clipboard Format Tag has four possible values:
- -| Value | -Identifier | -Description | -
|---|---|---|
-1L |
- CFTAG_WINDOWS |
- a built-in Windows© clipboard format value | -
-2L |
- CFTAG_MACINTOSH |
- a Macintosh clipboard format value | -
-3L |
- CFTAG_FMTID |
- a format identifier (FMTID) This is rarely used. | -
0L |
- CFTAG_NODATA |
- No data This is rarely used. | -
Windows clipboard data has four image formats for thumbnails:
- -| Value | -Identifier | -Description | -
|---|---|---|
| 3 | -CF_METAFILEPICT |
- Windows metafile format - recommended | -
| 8 | -CF_DIB |
- Device Independent Bitmap | -
| 14 | -CF_ENHMETAFILE |
- Enhanced Windows metafile format | -
| 2 | -CF_BITMAP |
- Bitmap - Obsolete - Use CF_DIB instead |
-
The most common format for thumbnails on the Windows platform is the - Windows metafile format. The Clipboard places and extra header in front of - a the standard Windows Metafile Format data.
- -The Clipboard Data byte array looks like this when an image is stored in - Windows' Clipboard WMF format.
- -| Identifier | -CF_METAFILEPICT | -mm | -width | -height | -handle | -WMF data | -
|---|---|---|---|---|---|---|
| Size | -32 bit unsigned int | -16 bit unsigned(?) int | -16 bit unsigned(?) int | -16 bit unsigned(?) int | -16 bit unsigned(?) int | -byte array - variable length | -
| Description | -Clipboard WMF | -Mapping Mode | -Image Width | -Image Height | -handle to the WMF data array in memory, or 0 | -standard WMF byte stream | -
FIXME: Describe the Device Independent Bitmap - format!
-FIXME: Describe the Macintosh clipboard formats!
-The following functionalities should be added to HPFS:
- -Add writing capability for property sets. Presently property sets can - be read only.
-Add codepage support: Presently the bytes making out the string in a - property's value are interpreted using the platform's default character - set.
-Add resource bundles to
- org.apache.poi.hpsf.wellknown to ease
- localizations. This would be useful for mapping standard property IDs to
- localized strings. Example: The property ID 4 could be mapped to "Author"
- in English or "Verfasser" in German.
Implement reading functionality for those property types that are not - yet supported. HPSF should return proper Java types instead of just byte - arrays.
-Add WMF to java.awt.Image example code in Thumbnail
- HOW TO.
- Maybe it's unwise to advertise your competitors but we believe - competition is good and we have the best support reading and - write Excel workbooks currently available. -
-| Product | -URL | -Description | -
| JSC | -- jsc.tomschuetz.com - | -Reading, calculating standard and VBA functions with - Java at runtime. - | -
| Formula One | -- ReportingEngines (division of Actuate Corporation) - | -An alternative to this project is to - buy the $5000 per server installation. | -
| Visual Basic | -- www.microsoft.com - | -Give up XML and write Visual Basic code on a Microsoft Windows based - Environment or output in Microsoft's beta and primarily undocumented - XML for office format. | -
| JExcel | -http://stareyes.homeip.net:8888 | -Frequently unavailable. Little currently known about it's capabilities. | -
| JWorkbook | -http://www.object-refinery.com/jworkbook/index.html | -This effort supports Gnumeric and Excel, however the Excel part is done using POI anyway. | -
| xlReader | -http://www.sourceforge.net/projects/xlrd | -Provides decent support for reading Excel. | -
| Excel ODBC Driver | -http://www.nwlink.com/~leewal/content/exceljavasample.htm | -ODBC offers a somewhat wierd method for using Excel. | -
| ExtenXLS | -http://www.extentech.com/products/ExtenXLS/docs/intro3.jsp | -Commercial library for reading, modifying and writing Excel spreadsheets. Not cheap but - certainly a lot more affordable than Formula 1. No idea as to it's quality. | -
| J-Integra Java-Excel Bridge | -http://www.intrinsyc.com/products/bridging/jintegra.asp | -Uses DCOM to an Excel instance on a windows machine. | -
| Perl & C | -- | -There are a number of perl and C libraries, however none of them are consistent. | -
| VistaJDBC | -http://www.vistaportal.com/products/vistajdbc.htm | -VistaJDBC driver works with both StarOffice and Excel spreadsheets and - can access data using standard SQL statements without any API programming. - VistaJDBC also implemented ability to choose by not just rows and columns but by - specific cells, ranges of cells, etc. - | -
| Coldtags Excel Tag Library | -http://www.servletsuite.com/servlets/exceltag.htm | -- This library outputs a simple CSV file, in which cells can - contain numbers or text. You could output a CSV file without its - help, but it gives a little more readability/structure to the code, and - could be extended to handle more complexity. When - you invoke one of these JSP pages from your browser, you open up an Excel - spreadsheet. There's no formatting, worksheets, or anything fancy like that. - So it's not strictly a competitor but it does the job. - | -
- This document is intended as a work in progress for describing - our current understanding of how the chart records are are - written to produce a valid chart. -
-- The following records detail the records written for a - 'simple' bar chart. -
-- The next section breaks those records down into an easier - to read format: -
-- Just a quick note on some of the unknown records: -
-- It is currently suspected that many of those records could be - left out when generating a bar chart from scratch. The way - we will be proceeding with this is to write code that generates - most of these records and then start removing them to see - how this effects the chart in excel. -
-
- - This section is intended for diagrams (UML/etc) that help - explain HSSF. -
-- Have more? Add a new "bug" to the bug database with [DOCUMENTATION] - prefacing the description and a link to the file on an http server - somewhere. If you don't have your own webserver, then you can email it - to (acoliver at apache dot org) provided its < 5MB. Diagrams should be - in some format that can be read at least on Linux and Windows. Diagrams - that can be edited are preferrable, but lets face it, there aren't too - many good affordable UML tools yet! And no they don't HAVE to be UML... - just useful. -
-- This document describes the current state of formula support in POI. - The information in this document applies to the 2.0-dev version of POI (i.e. CVS HEAD). - Since this area is a work in progress, this document will be updated with new features as and - when they are added. -
- -- In org.apache.poi.hssf.usermodel.HSSFCell - setCellFormula("formulaString") is used to add a formula to sheet and - getCellFormula() is used to retrieve the string representation of a formula. -
-- We aim to support the complete excel grammer for formulas. Thus, the string that you pass in - to the setCellFormula call should be what you expect to type into excel. Also, note - that you should NOT add a "=" to the front of the string. -
-- Formulas in Excel are stored as sequences of tokens in Reverse Polish Notation order. The - open office XLS spec is the best - documentation you will find for the format. -
- -- The tokens used by excel are modelled as individual *Ptg classes in the - org.apache.poi.hssf.record.formula package. -
-- The task of parsing a formula string into an array of RPN ordered tokens is done by the - org.apache.poi.hssf.record.formula.FormulaParser class. This class implements a hand - written recursive descent parser. -
-Check out the javadocs for details. -
-- You might find the - 'Excel 97 Developer's Kit' (out of print, Microsoft Press, no - restrictive covenants, available on Amazon.com) helpful for - understanding the file format. -
-- Also useful is the open office XLS spec. We - are collaborating with the maintainer of the spec so if you think you can add something to their - document just send through your changes. -
-- Low level records can be time consuming to created. We created a record - generator to help generate some of the simpler tasks. -
-- We use XML - descriptors to generate the Java code (which sure beats the heck out of - the PERL scripts originally used ;-) for low level records. The - generator is kinda alpha-ish right now and could use some enhancement, - so you may find that to be about 1/2 of the work. Notice this is in - org.apache.poi.hssf.record.definitions. -
-One thing to note: If you are making a large code contribution we need to ensure - any participants in this process have never - signed a "Non Disclosure Agreement" with Microsoft, and have not - received any information covered by such an agreement. If they have - they'll not be able to participate in the POI project. For large contributions we - may ask you to sign an agreement.
-Check our todo list or simply look for missing functionality. Start small - and work your way up.
-Make sure you read the contributing section - as it contains more generation information about contributing to Poi in general.
-This release of the how-to outlines functionality for the CVS HEAD. - Those looking for information on previous releases should - look in the documentation distributed with that release.
-- This release allows numeric and string cell values to be written to - or read from an XLS file as well as reading and writing dates. Also - in this release is row and column sizing, cell styling (bold, - italics, borders,etc), and support for both built-in and user - defined data formats. New - to this release is an event-based API for reading XLS files. - It differs greatly from the read/write API - and is intended for intermediate developers who need a smaller - memory footprint. It will also serve as the basis for the HSSF - Generator.
-The high level API (package: org.apache.poi.hssf.usermodel) - is what most people should use. Usage is very simple. -
-Workbooks are created by creating an instance of - org.apache.poi.hssf.usermodel.HSSFWorkbook. -
-Sheets are created by calling createSheet() from an existing - instance of HSSFWorkbook, the created sheet is automatically added in - sequence to the workbook. Sheets do not in themselves have a sheet - name (the tab at the bottom); you set - the name associated with a sheet by calling - HSSFWorkbook.setSheetName(sheetindex,"SheetName",encoding). - The name may be in 8bit format (HSSFWorkbook.ENCODING_COMPRESSED_UNICODE) - or Unicode (HSSFWorkbook.ENCODING_UTF_16). Default encoding is 8bit per char. -
-Rows are created by calling createRow(rowNumber) from an existing - instance of HSSFSheet. Only rows that have cell values should be - added to the sheet. To set the row's height, you just call - setRowHeight(height) on the row object. The height must be given in - twips, or 1/20th of a point. If you prefer, there is also a - setRowHeightInPoints method. -
-Cells are created by calling createCell(column, type) from an - existing HSSFRow. Only cells that have values should be added to the - row. Cells should have their cell type set to either - HSSFCell.CELL_TYPE_NUMERIC or HSSFCell.CELL_TYPE_STRING depending on - whether they contain a numeric or textual value. Cells must also have - a value set. Set the value by calling setCellValue with either a - String or double as a parameter. Individual cells do not have a - width; you must call setColumnWidth(colindex, width) (use units of - 1/256th of a character) on the HSSFSheet object. (You can't do it on - an individual basis in the GUI either).
-Cells are styled with HSSFCellStyle objects which in turn contain - a reference to an HSSFFont object. These are created via the - HSSFWorkbook object by calling createCellStyle() and createFont(). - Once you create the object you must set its parameters (colors, - borders, etc). To set a font for an HSSFCellStyle call - setFont(fontobj). -
-Once you have generated your workbook, you can write it out by - calling write(outputStream) from your instance of Workbook, passing - it an OutputStream (for instance, a FileOutputStream or - ServletOutputStream). You must close the OutputStream yourself. HSSF - does not close it for you. -
-Here is some example code (excerpted and adapted from - org.apache.poi.hssf.dev.HSSF test class):
-Reading in a file is equally simple. To read in a file, create a -new instance of org.apache.poi.poifs.Filesystem, passing in an open InputStream, such as a FileInputStream -for your XLS, to the constructor. Construct a new instance of -org.apache.poi.hssf.usermodel.HSSFWorkbook passing the -Filesystem instance to the constructor. From there you have access to -all of the high level model objects through their assessor methods -(workbook.getSheet(sheetNum), sheet.getRow(rownum), etc). -
-Modifying the file you have read in is simple. You retrieve the -object via an assessor method, remove it via a parent object's remove -method (sheet.removeRow(hssfrow)) and create objects just as you -would if creating a new xls. When you are done modifying cells just -call workbook.write(outputstream) just as you did above.
-An example of this can be seen in -org.apache.poi.hssf.dev.HSSF.
-The event API is brand new. It is intended for intermediate - developers who are willing to learn a little bit of the low level API - structures. Its relatively simple to use, but requires a basic - understanding of the parts of an Excel file (or willingness to - learn). The advantage provided is that you can read an XLS with a - relatively small memory footprint. -
-To use this API you construct an instance of - org.apache.poi.hssf.eventmodel.HSSFRequest. Register a class you - create that supports the - org.apache.poi.hssf.eventmodel.HSSFListener interface using the - HSSFRequest.addListener(yourlistener, recordsid). The recordsid - should be a static reference number (such as BOFRecord.sid) contained - in the classes in org.apache.poi.hssf.record. The trick is you - have to know what these records are. Alternatively you can call - HSSFRequest.addListenerForAllRecords(mylistener). In order to learn - about these records you can either read all of the javadoc in the - org.apache.poi.hssf.record package or you can just hack up a - copy of org.apache.poi.hssf.dev.EFHSSF and adapt it to your - needs. TODO: better documentation on records.
-Once you've registered your listeners in the HSSFRequest object - you can construct an instance of - org.apache.poi.poifs.filesystem.FileSystem (see POIFS howto) and - pass it your XLS file inputstream. You can either pass this, along - with the request you constructed, to an instance of HSSFEventFactory - via the HSSFEventFactory.processWorkbookEvents(request, Filesystem) - method, or you can get an instance of DocumentInputStream from - Filesystem.createDocumentInputStream("Workbook") and pass - it to HSSFEventFactory.processEvents(request, inputStream). Once you - make this call, the listeners that you constructed receive calls to - their processRecord(Record) methods with each Record they are - registered to listen for until the file has been completely read. -
-A code excerpt from org.apache.poi.hssf.dev.EFHSSF (which is - in CVS or the source distribution) is reprinted below with excessive - comments:
-The low level API is not much to look at. It consists of lots of -"Records" in the org.apache.poi.hssf.record.* package, -and set of helper classes in org.apache.poi.hssf.model.*. The -record classes are consistent with the low level binary structures -inside a BIFF8 file (which is embedded in a POIFS file system). You -probably need the book: "Microsoft Excel 97 Developer's Kit" -from Microsoft Press in order to understand how these fit together -(out of print but easily obtainable from Amazon's used books). In -order to gain a good understanding of how to use the low level APIs -should view the source in org.apache.poi.hssf.usermodel.* and -the classes in org.apache.poi.hssf.model.*. You should read the -documentation for the POIFS libraries as well.
-The HSSF application is nothing more than a test for the high -level API (and indirectly the low level support). The main body of -its code is repeated above. To run it: -
-export HSSFDIR={wherever you put HSSF's jar files}
-export LOG4JDIR={wherever you put LOG4J's jar files}
-export CLASSPATH=$CLASSPATH:$HSSFDIR/hssf.jar:$HSSFDIR/poi-poifs.jar:$HSSFDIR/poi-util.jar:$LOG4JDIR/jog4j.jar
- java org.apache.poi.hssf.dev.HSSF ~/myxls.xls writeThis should generate a test sheet in your home directory called "myxls.xls".
java org.apache.poi.hssf.dev.HSSF ~/input.xls output.xls
- Poi can dynamically select it's logging implementation. Poi trys to - create a logger using the System property named "org.apache.poi.util.POILogger". - Out of the box this can be set to one of three values: -
-- If the property is not defined or points to an invalid classthen the NullLogger is used. -
-- Refer to the commons logging package level javadoc for more information concerning how to - configure commons logging. -
-HSSF has a number of tools useful for developers to debug/develop -stuff using HSSF (and more generally XLS files). We've already -discussed the app for testing HSSF read/write/modify capabilities; -now we'll talk a bit about BiffViewer. Early on in the development of -HSSF, it was decided that knowing what was in a record, what was -wrong with it, etc. was virtually impossible with the available -tools. So we developed BiffViewer. You can find it at -org.apache.poi.hssf.dev.BiffViewer. It performs two basic -functions and a derivative. -
-The first is "biffview". To do this you run it (assumes -you have everything setup in your classpath and that you know what -you're doing enough to be thinking about this) with an xls file as a -parameter. It will give you a listing of all understood records with -their data and a list of not-yet-understood records with no data -(because it doesn't know how to interpret them). This listing is -useful for several things. First, you can look at the values and SEE -what is wrong in quasi-English. Second, you can send the output to a -file and compare it. -
-The second function is "big freakin dump", just pass a -file and a second argument matching "bfd" exactly. This -will just make a big hexdump of the file. -
-Lastly, there is "mixed" mode which does the same as -regular biffview, only it includes hex dumps of certain records -intertwined. To use that just pass a file with a second argument -matching "on" exactly.
-In the next release cycle we'll also have something called a -FormulaViewer. The class is already there, but its not very useful -yet. When it does something, we'll document it.
- -This release contains code that supports "internationalization" -or more accurately non-US/UK languages; however, it has not been -tested with the new API changes (please help us with this). We've -shifted focus a bit for this release in recognition of the -international support we've gotten. We're going to focus on western -European languages for our first beta. We're more than happy to -accept help in supporting non-Western European languages if someone -who knows what they're doing in this area is willing to pitch in! -(There is next to no documentation on what is necessary to support -such a move and its really hard to support a language when you don't even -know the alphabet).
-This release of HSSF does not yet support Formulas. I've been -focusing on the requests I've gotten in. That being said, if we get -more user feedback on what is most useful first we'll aim for that. -As a general principal, HSSF's goal is to support HSSF-Serializer -(meaning an emphasis on write). We would like to hear from you! How -are you using HSSF/POIFS? How would you like to use it? What features -are most important first? -
-HSSF is the POI Project's pure Java implementation of the Excel '97(-2002) file format.
-HSSF provides a way to read spreadsheets create, modify, read and write XLS spreadsheets - It provides: -
-- Truth be told there is probably a better way to generate your spreadsheet - generation (yet you'll still be using HSSF indirectly). At the time of - this writing we're in the process of moving the HSSF Serializer over to - the Apache Cocoon - Project. With Cocoon you can serialize any XML datasource (of - which might be a ESQL page outputting in SQL for instance) by simply - applying the stylesheet and designating the serializer. -
-- If you're merely reading spreadsheet data, then use the eventmodel api - in the org.apache.poi.hssf.eventmodel package. -
-- If you're modifying spreadsheet data then use the usermodel api. You - can also generate spreadsheets this way, but using Cocoon (which will do - it this way indirectly) is the best way...we promise. -
- -- The intent of this document is to outline some of the known limitations of the - POI HSSF API's. It is not intended to be complete list of every bug or missing - feature of HSSF, rather it's purpose is to provide a broad feel for some of the - functionality that is missing or broken. -
-- Want to use HSSF read and write spreadsheets in a hurry? This guide is for you. If you're after - more in-depth coverage of the HSSF user-API please consult the HOWTO - guide as it contains actual descriptions of how to use this stuff. -
-- The convenience functions live in contrib and provide - utility features such as setting borders around merged - regions and changing style attributes without explicitly - creating new styles. -
-- The zoom is expressed as a fraction. For example to - express a zoom of 75% use 3 for the numerator and - 4 for the denominator. -
-- There are two types of panes you can create; freeze panes and split panes. -
-- A freeze pane is split by columns and rows. You create - a freeze pane using the following mechanism: -
-- sheet1.createFreezePane( 3, 2, 3, 2 ); -
-- The first two parameters are the columns and rows you - wish to split by. The second two parameters indicate - the cells that are visible in the bottom right quadrant. -
-- - Split pains appear differently. The split area is - divided into four separate work area's. The split - occurs at the pixel level and the user is able to - adjust the split by dragging it to a new position. -
-- - Split panes are created with the following call: -
-- sheet2.createSplitPane( 2000, 2000, 0, 0, HSSFSheet.PANE_LOWER_LEFT ); -
-- - The first parameter is the x position of the split. - This is in 1/20th of a point. A point in this case - seems to equate to a pixel. The second parameter is - the y position of the split. Again in 1/20th of a point. -
-- The last parameter indicates which pane currently has - the focus. This will be one of HSSFSheet.PANE_LOWER_LEFT, - PANE_LOWER_RIGHT, PANE_UPPER_RIGHT or PANE_UPPER_LEFT. -
-- It's possible to set up repeating rows and columns in - your printouts by using the setRepeatingRowsAndColumns() - function in the HSSFWorkbook class. -
-- This function Contains 5 parameters. - The first parameter is the index to the sheet (0 = first sheet). - The second and third parameters specify the range for the columns to repreat. - To stop the columns from repeating pass in -1 as the start and end column. - The fourth and fifth parameters specify the range for the rows to repeat. - To stop the columns from repeating pass in -1 as the start and end rows. -
-- Example is for headers but applies directly to footers. -
-- The record generator was born from frustration with translating - the Excel records to Java classes. Doing this manually is a time - consuming process. It's also very easy to make mistakes. -
-- A utility was needed to take the defintition of what a - record looked like and do all the boring and repetitive work. -
-- The record generator takes XML as input and produces the following - output: -
- The record generator is invoked as an Ant target
- (generate-records). It goes through looking for all files in
- src/records/defintitions ending with _record.xml.
- It then creates two files; the Java record definition and the
- Java test case template.
-
- The records themselves have the following general layout: -
-- The following table details the allowable types and sizes for - the fields. -
-| Type | -Size | -Java Type | -
|---|---|---|
| int | -1 | -byte | -
| int | -2 | -short | -
| int | -4 | -int | -
| int | -8 | -long | -
| int | -varword | -array of shorts | -
| bits | -1 | -A byte comprising of a bits (defined by the bit element) - | -
| bits | -2 | -An short comprising of a bits | -
| bits | -4 | -A int comprising of a bits | -
| float | -8 | -double | -
| hbstring | -java expression | -String | -
- The Java records are regenerated each time the record generator is - run, however the test stubs are only created if the test stub does - not already exist. What this means is that you may change test - stubs but not the generated records. -
-- Occationally the builtin types are not enough. More control - over the encoding and decoding of the streams is required. This - can be achieved using a custom type. -
-- A custom type lets you escape to java to define the way in which - the field encodes and decodes. To code a custom type you - declare your field like this: -
-
- Where the class name specified after custom: is a
- class implementing the interface CustomField.
-
- You can then implement the encoding yourself. -
-- The record generation works by taking an XML file and styling it - using XLST. Given that XSLT is a little limited in some ways it was - necessary to add a little Java code to the mix. -
-- See record.xsl, record_test.xsl, FieldIterator.java, - RecordUtil.java, RecordGenerator.java -
-- There is a corresponding "type" generator for HDF. - See the HDF documentation for details. -
-- The record generator does not handle all possible record types and - goes not intend to perform this function. When dealing with a - non-standard record sometimes the cost-benifit of coding the - record by hand will be greater than attempting modify the - generator. The main point of the record generator is to save - time, so keep that in mind. -
-- Currently the the XSL file that generates the record calls out to - Java objects. The Java code for the record generation is - currently quite messy with minimal comments. -
-Primary Actor: HSSF client
-Scope: HSSF
-Level: Summary
-Stakeholders and Interests:
-Precondition: None
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions:
-2a. Exceptions -thrown by POIFS will be passed on to the HSSF client.
-Primary Actor: HSSF client
-Scope: HSSF
-Level: Summary
-Stakeholders and Interests:
-Precondition:
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions:
-3a. Exceptions -from POIFS are passed to the HSSF client.
- -Primary Actor: HSSF client
-Scope: HSSF
--Level: Summary
-Stakeholders and Interests:
-Precondition:
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions: -None
- -Primary Actor: HSSF
-Scope: HSSF
--Level: Summary
-Stakeholders and Interests:
-Precondition:
-Minimal -Guarantee: None
-Main Success Guarantee:
-Extensions:
-3a. Exceptions -thrown by POIFS will be passed on
-Primary Actor: HSSF
-Scope: HSSF
--Level: Summary
-Stakeholders and Interests:
-Precondition: -
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions:None
-- You can now read your POI news in a handy dandy - RSS feed or read it here (links to - other syndication formats there as well). Thanks to the good guys of the - Blojsom project for writing such - a great piece of software! Subscribe using your favorite aggregator today and - stay current on important POI news and events such as releases, new development - features, etc. -
-- The latest development release of POI is version 1.10. - Binary distributions are available here - and source distributions are here. -
- - - -- The POI documentation translation project has begun. The first ones - to start are the Spanish - (espaniol) and Japanese, and - German - translations. Others are welcome. Please feel - free to participate! -
-- Voting for the POI logo contest is now complete. Thank you for your votes. -
- - - -- The POI project consists of APIs for manipulating various file formats - based upon Microsoft's OLE 2 Compound Document format using pure Java. -
-- OLE 2 Compound Document Format based files include most Microsoft Office - files such as XLS and DOC. -
-- As a general policy we try to collaborate as much as possible with other projects to - provide this functionality. Examples include: Cocoon for - which you'll soon find generators and serializers for our projects; - Open Office.org with whom we collaborate in documenting the - XLS format; and Lucene for which we'll soon have file - format interpretors. When practical, we donate components directly to those projects for POI-enabling them. -
-- We'll tackle this on a component level. POI refers to the whole project. -
-- So why should you use POIFS or HSSF? -
-- You'd use POIFS if you had a document written in OLE 2 Compound Document Format, probably written using - MFC, that you needed to read in Java. Alternatively, you'd use POI to write OLE 2 Compound Document Format - if you needed to inter-operate with software running on the Windows platform. We are not just bragging when - we say that POIFS is the most complete and correct port of this file format to date! -
-- You'd use HSSF if you needed to read or write an XLS (Excel) file using Java. You can also read and modify - spreadsheets using this API, although right now writing is more mature. -
-- POI stands for Poor Obfuscation Implementation. Why would we name our project such a derogatory name? Well, - Microsoft's OLE 2 Compound Document Format is a poorly conceived thing. It is essentially an archive structured - much like the old DOS FAT filesystem. Redmond chose, instead of using tar, gzip, zip or arc, to invent their own - archive format that does not provide any standard encryption or compression, is not very appendable and is prone - to fragmentation. -
-- Poi is also a Hawaiian delicacy that Merriam Webster's dictionary defines as: - "A Hawaiian food of taro root cooked, pounded, and kneaded to a paste and often allowed to ferment." This seemed - strangely descriptive of the file format. -
-- So if you like acronyms, then POI is an acronym. If you hate them, then we just used the name of the food for our - project. If you wish to signify your love or hate for acronyms, use POI or Poi to refer to the project respectively. -
-A common misconception is that POI writes Excel files. POI is the name of the project. POI contains several - components, one of which, HSSF, writes Excel files. The following are components of the entire POI project - and a brief summary of their purpose.
-POIFS is the oldest and most stable part of the project. It is our port of the OLE 2 Compound Document Format to - pure Java. It supports both read and write functionality. All of our components ultimately rely on it by - definition. Please see the POIFS project page for more information.
-HSSF is our port of the Microsoft Excel 97(-2002) file format (BIFF8) to pure Java. It supports read and write - capability. Please see the HSSF project page for more information.
-HDF is our port of the Microsoft Word 97 file format to pure Java. It supports read and write capability. - Please see the HDF project page for more information. This component is - in the early stages of design. Jump in!
-HPSF is our port of the OLE 2 property set format to pure - Java. Property sets are mostly use to store a document's properties - (title, author, date of last modification etc.), but they can be used - for application-specific purposes as well. Currently HPSF supports - read functionality only. Please see the HPSF project page for more - information.
-The HSSF Serializer, which was part of our 1.0 release and last builds on - Sourceforge, has been donated to the - Cocoon project, and is available starting from version - 2.0.2.
-- So you'd like to contribute to the project? Great! We need enthusiastic, hard-working, talented folks to help - us on the project in several areas. The first is bug reports and feature requests! The second is documentation - - we'll be at your every beck and call if you've got a critique or you'd like to contribute or otherwise improve - the documentation. We could especially use some help documenting the HSSF file format! Last, but not least, we - could use some binary crunching Java coders to chew through the convolution that characterizes Microsoft's file - formats and help us port new ones to a superior Java platform! -
-So if you're motivated, ready, and have the time, join the mail lists and we'll be happy to help you get started on the - project! -
- - -- These are mirrors of the - POI website. - If you know of others...report them! :-) -
-- These are articles/etc. posted about POI around the web. If you - see POI in the news or mentioned at least somewhat prominently - on a site (not your homepage that you put the work POI on in - order to get us to link you and by the why here is a picture of - your wife in kids) then send a patch to the list. In general - equal time will be given so please feel free to send inflamatory - defamation as well as favorable, technical and factual. Really - stupid things won't be mentioned (sorry). -
-- If you can read one of these languages, send mail to the list - telling us what language it is and we'll categorize it! -
-- Here are the current logo submissions. Thanks to the artists! -
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The POI project is the master project for developing pure - Java ports of file formats based on Microsoft's OLE 2 Compound - Document Format. OLE 2 Compound Document Format is used by - Microsoft Office Documents, as well as by programs using MFC - property sets to serialize their document objects. -
-- There following are ports, packages or components contained in the POI project. -
-- POIFS is the set of APIs - for reading and writing OLE 2 Compound Document Formats using (only) Java. -
-- HSSF is the set of APIs - for reading and writing Microsoft Excel 97(-XP) spreadsheet using (only) Java. -
-- HDF is the set of APIs - for reading and writing Microsoft Word 97(-XP) spreadsheet using (only) Java. -
-- HPSF is the set of APIs - for reading property sets using (only) Java. -
-- POI-Utils are general purpose artifacts - from POI development that have not yet been implemented elsewhere. We're - always looking to donate these and maintain them as part of a general library - used in another project. These are things we need to complete our mission but - are generally outside of it. -
-
- This is an informal list - in chronological order -
- of some of the noteworthy patches that have been posted
- to the developers mailing list.
- These patches are not (yet) part of the Poi project, but need reviewing for possible
- inclusion. This system was instituted because, due to the large volume of mail and
- the lack of time of the committers, some patches tended to get forgotten about. This
- queue does not guarantee that any patch will be reviewed within a reasonable time frame,
- but it does at least make them easier to find!
-
Reviewers wanted! - If you have time to review and/or test these patches, - we would be grateful for your time. Please post comments to the dev mailing lists. -
- Before submitting a patch, please read the page on
diff -u format from CVSFollowing the above guidelines will facilitate your patch being reviewed - and applied efficiently.
[Under Construction] Archive links will be added later.
- Please do not bother the patch submitters/authors without first reading the
- relevant post(s) in the
Vapourware will not be listed.
| id | Summary | Reviewer | Resolution | Status |
|---|
See also additional list of patches to be added in
- (21-Jan-02) While this document is just full of useful project - introductory information and I do suggest those interested in getting - involved in the project read it, it is woefully out of date. -
-- We deliberately allowed this document to run out of date because it - is a good reflection of what the original vision was for POI 1.0. - You'll note that some of the terminology is not used in quite the same - way any longer. I've made some minor corrections where reading this - confused me. An example: in some places this document may refer to - POI API instead of POIFS API. When this vision was written we had - an incomplete understanding of the project. -
-- Lastly, the scope of the project expanded dramatically near the end - of the 1.0 cycle. Our vision at the time was to focus merely on the - Excel port (having no idea how the project would grow or be received) - and provide the OLE 2 Compound Document port for others to port later - formats. We now plan to spearhead these ports under the umbrella of - the POI project. So, you've been warned. Read on, but just realize - that we had a fuzzy view of things to come, and hindsight is 20-20. -
-- If I recall major holes were: a complete understanding of the format - of OLE 2 Compound Document format, Excel file format, and exactly how - Cocoon 2 Serializers worked. (that just about covers the whole range - huh?) -
-- The purpose of this document is to - collect, analyze and define high-level requirements, user needs and - features of the HSSF Serializer for Cocoon 2 and related libraries. - The HSSF Serializer is a java class supporting the Serializer - interface from the Cocoon 2 project and outputting in a compatible - format of that used by the spreadsheet program Microsoft Excel '97. - The HSSF Serializer will be responsible for converting XML - spreadsheet-like documents into Excel-compatible XLS spreadsheets. -
-- Many web apps today hit a brick wall - when it comes to the user request that they be able to easily - manipulate their reports and data extracts in the popular Microsoft - Excel spreadsheet format. This often causes inferior technologies to be - chosen for the project simply because they easily support this - format. This project seeks to extend existing XML, Java and Apache - Cocoon 2 project technologies by: -
- -- There are a number of enthusiastic - users of XML, UNIX and Java technology. Secondly, the Microsoft - solution for outputting Office Document formats often involves - actually manipulating the software as an OLE Server. This method - provides extremely low performance, extremely high overhead and is - only capable of handling one document at a time. -
-- The users of this software shall be - developers in a Java environment on any Operating System or power - users who are capable of XML document generation/deployment. -
-- The OLE 2 Compound Document format is - undocumented for all practical purposes and cryptic for all - impractical purposes. Developer needs in this area include - documentation and an easy to use library for reading and writing in - this format without requiring the developer to have intimate - knowledge of the format. -
-- There is currently no good way to write - to Microsoft Excel documents from Java or from a non-Microsoft - Windows based platform for that matter. Developers need an easy to - use library that supports a reasonable feature set and allows - seperation of data from formatting/stylistic concerns. -
-- There is currently no good way to - transform XML data to Microsoft Excel. Apache's Cocoon 2 project - supplies a complete framework for XML, but nothing for outputting in - Excel's XLS format. Developers and power users alike need a simple - method to output XML documents to Excel through server-side - processing. -
- - -- Originally there weren't any decent alternatives for reading or writing - to Excel. This has changed somewhat. -
-- The produced code shall be licensed by - the Apache License as used by the Cocoon 2 project and maintained on - a project page until such time as the Cocoon 2 developers accept it - as a donation (at which time the copyright will be turned over to - them). -
-- For developers on a Java and/or XML - environment this project will provide all the tools necessary for - outputting XML data in the Microsoft Excel format. This project seeks - to make the use of Microsoft Windows based servers unnecessary for - file format considerations and to fully document the OLE 2 Compound - Document format. The project aims not only to provide the tools for - serializing XML to Excel's file format and the tools for writing to - that file format from Java, but also to provide the tools for later - projects to convert other OLE 2 Compound Document formats to pure - Java APIs. -
-- HSSF Serializer for Apache Cocoon 2 -
-| - Benefit - | -- Supporting Features - | -
| - Standard XML tag language for sheet data - | -- Serializer will transform documents utilizing a defined tag - language - | -
| - Utilize XML to output in Excel - | -- Serializer will output in Excel - | -
| - Java API to output in Excel on any platform - | -- The project will develop an API that outputs in Excel using - pure Java. - | -
| - Make it easy for developers to port other OLE 2 Compound - Document-based formats to Java. - | -- The POIFS library will contain both a high-level abstraction - along with low-level constructs. The project will fully document - the OLE 2 Compound Document Format. - | -
- The POIFS API will include: -
-- The HSSF API will include: -
-- The POI Filesystem API includes: -
-- The HSSF API includes: -
-- The HSSF Serializer subproject: -
-- All Java code will be 100% pure Java. -
-- The minimum system requirements for POIFS are: -
-- The minimum system requirements for HSSF are: -
-- The minimum system requirements for the HSSF Serializer are: -
-- All components must perform well enough - to be practical for use in a webserver environment (especially - Cocoon2/Tomcat/Apache combo) -
-- The software will run primarily in - developer environments. We should make some allowances for - not-highly-technical users to write XML documents for the HSSF - Serializer. All other components will assume intermediate Java 2 - knowledge. No XML knowledge will be required except for using the - HSSF Serializer. As much documentation as is practical shall be - required for all components as XML is relatively new, and the - concepts introduced for writing spreadsheets and to POI filesystems - will be brand new to Java and many Java developers. -
-- The filesystem as read and written by - POI shall be fully documented and explained so that the average Java - developer can understand it. -
-- The POI API will be fully documented - through Javadoc. A walkthrough of using the high level POI API shall - be provided. No documentation outside of the Javadoc shall be - provided for the low-level POI APIs. -
-- The HSSF File Format as implemented by - the HSSF API will be fully documented. No documentation will be - provided for features that are not supported by HSSF API that are - supported by the Excel 97 File Format. Care will be taken not to - infringe on any "legal stuff". -
-- The HSSF API will be documented by - javadoc. A walkthrough of using the high level HSSF API shall be - provided. No documentation outside of the Javadoc shall be provided - for the low level HSSF APIs. -
-- The HSSF Serializer will be documented - by javadoc. -
-- The XML tag language along with - function and usage shall be fully documented. Examples will be - provided as well. -
-- filesystem shall refer only to the POI formatted archive. -
-- file shall refer to the embedded data stream within a - POI filesystem. This will be the actual embedded document. -
-- This is the POI 2.0 cycle vision document. Although the vision - has not changed and this document is certainly not out of date and - the vision has not changed, the structure of the project has - changed a bit. We're not going to change the vision document to - reflect this (however proper that may be) because it would only - involve deletion. There is no purpose in providing less - information provided we give clarification. -
-- This document was created before the POI components for - Apache Cocoon - were accepted into the Cocoon project itself. It was also - written before POI was accepted into Jakarta. So while the - vision hasn't changed some of the components are actually now - part of other projects. We'll still be working on them on the - same timeline roughly (minus the overhead of coordination with - other groups), but they are no longer technically part of the - POI project itself. -
-- The purpose of this document is to - collect, analyze and define high-level requirements, user needs, - and features of the second release of the POI project software. - The POI project currently consists of the following components: - the HSSF Serializer, the HSSF library and the POIFS library. -
-By the completion of this release cycle the POI project will also - include the HSSF Generator and the HDF library. -
-- The first release of the POI project - was an astounding success. This release seeks to build on that - success by: -
-- There are a number of enthusiastic - users of XML, UNIX and Java technology. Furthermore, the Microsoft - solution for outputting Office Document formats often involves - actually manipulating the software as an OLE Server. This method - provides extremely low performance, extremely high overhead and is - only capable of handing one document at a time. -
-- The users of this software shall be - developers in a Java environment on any operating system, or power - users who are capable of XML document generation/deployment. -
-- The HSSF library currently requires a - full object representation to be created before reading values. This - results in very high memory utilization. We need to reduce this - substantially for reading. It would be preferable to do this for - writing, but it may not be possible due to the constraints imposed by - the file format itself. Memory utilization during read is our top - user complaint. -
-- The POIFS library currently requires a - full object representation to be created before reading values. This - results in very high memory utilization. We need to reduce this - substantially for reading. -
-- The HSSF library currently ignores - formula cells and identifies them as "UnknownRecord" at the - lower level of the API. We must provide a way to read and write - formulas. This is now the top requested feature. -
-- The HSSF library currently does not support - charts. This is a key requirement of some users who wish to use HSSF - in a reporting engine. -
-- The HSSF Serializer currently does not - provide serialization for cell styling. User's will want stylish - spreadsheets to result from their XML. -
-- There is currently no way to generate - the XML from an XLS that is consistent with the format used by the - HSSF Serializer. -
-- There should be a way to read and write - the DOC file format using pure Java. -
- -- Originally there weren't any decent alternatives for reading or writing - to Excel. This has changed somewhat. -
-- The produced code shall be licensed by - the Apache License as used by the Cocoon 2 project (APL 1.1) and - maintained on at http://poi.sourceforge.net - and http://sourcefoge.net/projects/poi. - It is our hope to at some point integrate with the various Apache - projects (xml.apache.org and jakarta.apache.org), at which point we'd - turn the copyright over to them. -
-- For developers on a Java and/or XML - environment this project will provide all the tools necessary for - outputting XML data in the Microsoft Excel format. This project seeks - to make the use of Microsoft Windows based servers unnecessary for - file format considerations and to fully document the OLE 2 Compound - Document format. The project aims not only to provide the tools for - serializing XML to Excel and Word file formats and the tools for - writing to those file formats from Java, but also to provide the - tools for later projects to convert other OLE 2 Compound Document - formats to pure Java APIs. -
-- HSSF Serializer for Apache Cocoon 2 -
-| - Benefit - | -- Supporting Features - | -
| - Ability to serialize styles from XML spreadsheets. - | -- HSSFSerialzier will support styles. - | -
| - Ability to read and write formulas in XLS files. - | -- HSSF will support reading/writing formulas. - | -
| - Ability to output in MS Word on any platform using Java. - | -- The project will develop an API that outputs in Word format - using pure Java. - | -
| - Enhance performance for reading and writing XLS files. - | -- HSSF will undergo a number of performance enhancements. HSSF - will include a new event-based API for reading XLS files. POIFS - will support a new event-based API for reading OLE2 CDF files. - | -
| - Ability to generate XML from XLS files - | -- The project will develop an HSSF Generator. - | -
| - The ability to generate charts - | -- HSSF will provide low level support for chart records as well - as high level API support for generating charts. The ability - to read chart information will not initially be provided. - | -
- Enhancements to the POIFS API will - include: -
-- Enhancements to the HSSF API will - include: -
-- The HSSF Generator will include: -
-- The HDF API will include: -
-- All Java code will be 100% pure Java. -
-- The minimum system requirements for the POIFS API are: -
-- The minimum system requirements for the the HSSF API are: -
-- The minimum system requirements for the the HDF API are: -
-- The minimum system requirements for the HSSF Serializer are: -
-- All components must perform well enough - to be practical for use in a webserver environment (especially - the "killer trio": Cocoon2/Tomcat/Apache combo) -
-- The software will run primarily in - developer environments. We should make some allowances for - not-highly-technical users to write XML documents for the HSSF - Serializer. All other components will assume intermediate Java 2 - knowledge. No XML knowledge will be required except for using the - HSSF Serializer. As much documentation as is practical shall be - required for all components as XML is relatively new, and the - concepts introduced for writing spreadsheets and to POI filesystems - will be brand new to Java and many Java developers. -
-- The filesystem as read and written by - POI shall be fully documented and explained so that the average Java - developer can understand it. -
-- The POI API will be fully documented - through Javadoc. A walkthrough of using the high level POI API shall - be provided. No documentation outside of the Javadoc shall be - provided for the low-level POI APIs. -
-- The HSSF File Format as implemented by - the HSSF API will be fully documented. No documentation will be - provided for features that are not supported by HSSF API that are - supported by the Excel 97 File Format. Care will be taken not to - infringe on any "legal stuff". Additionally, we are - collaborating with the fine folks at OpenOffice.org on - *free* documentation of the format. -
-- The HSSF API will be documented by - javadoc. A walkthrough of using the high level HSSF API shall be - provided. No documentation outside of the Javadoc shall be provided - for the low level HSSF APIs. -
-- The HDF API will be documented by - javadoc. A walkthrough of using the high level HDF API shall be - provided. No documentation outside of the Javadoc shall be provided - for the low level HDF APIs. -
-- The HSSF Serializer will be documented - by javadoc. -
-- The HSSF Generator will be documented - by javadoc. -
-- The XML tag language along with - function and usage shall be fully documented. Examples will be - provided as well. -
-- filesystem shall refer only to the POI formatted archive. -
-- file shall refer to the embedded data stream within a - POI filesystem. This will be the actual embedded document. -
-This is a collection of notes to assist with long-term planning and - development. -
- -There is much discussion of issues and research topics (RT) threads on
- the dev mailing list (and elsewhere). However, details
- get lost in the sheer volume. This is the place to document the summary of
- discussions on some key topics. Some new and complex capabilities will take
- lots of design and specification before they can be implemented.
-
Another use for this collection of notes is as a place to quickly store - a snippet from an email discussion or even a link to a discussion thread. - The concepts can then be fleshed-out over time. -
- -Anyone can participate in this process. Please get involved in discussion
- on dev and contribute patches for these summary planning
- documents via the normal contribution
- process.
-
These planning documents are intended to be concise notes only. They are - also ever-evolving, because as issues are addressed these notes will be - revised. -
-dev email archives for other issuesTodo
- -POIFS file systems are essentially normal files stored on a - Java-compatible platform's native file system. They are - typically identified by names ending in a four character - extension noting what type of data they contain. For - example, a file ending in ".xls" would likely - contain spreadsheet data, and a file ending in - ".doc" would probably contain a word processing - document. POIFS file systems are called "file - system", because they contain multiple embedded files - in a manner similar to traditional file systems. Along - functional lines, it would be more accurate to call these - POIFS archives. For the remainder of this document it is - referred to as a file system in order to avoid confusion - with the "files" it contains.
-POIFS file systems are compatible with those document - formats used by a well-known software company's popular - office productivity suite and programs outputting - compatible data. Because the POIFS file system does not - provide compression, encryption or any other worthwhile - feature, its not a good choice unless you require - interoperability with these programs.
-The POIFS file system does not encode the documents - themselves. For example, if you had a word processor file - with the extension ".doc", you would actually - have a POIFS file system with a document file archived - inside of that file system.
-This document utilizes the numeric types as described by - the Java Language Specification, which can be found at - http://java.sun.com. In - short:
-The Java Language Specification spells out a number of - other types that are not referred to by this document.
-Where this document makes references to "endian
- conversion" it is referring to the byte order of
- stored numbers. Numbers in "little-endian order"
- are stored with the least significant byte first. In
- order to properly read a short, for example, you'd read two
- bytes and then shift the second byte 8 bits to the left
- before performing an or operation to it
- against the first byte. The following code illustrates this
- method:
This is a walkthrough of a POIFS file system and how it is - put together. It is not intended to give a concise - description but to give a "big picture" of the - general structure and how it's interpreted.
-A POIFS file system begins with a header. This header - identifies locations in the file by function and provides a - sanity check identifying a file as a POIFS file system.
-The first 64 bits of the header compose a magic number - identifier. This identifier tells the client software - that this is indeed a POIFS file system and that it should - be treated as such. This is a "sanity check" to - make sure this is a POIFS file system and not some other - format. The header also contains an array of block - numbers. These block numbers refer to blocks in the - file. When these blocks are read together they form the - Block Allocation Table. The header also contains a - pointer to the first element in the property table, - also known as the root element, and a pointer to the - small Block Allocation Table (SBAT).
-The block allocation table or BAT, along with - the property table, specify which blocks in the file - system belong to which files. After the header block, the - file system is divided into identically sized blocks of - data, numbered from 0 to however many blocks there are in - the file system. For each file in the file system, its - entry in the property table includes the index of the first - block in the array of blocks. Each block's index into the - array of blocks is also its index into the BAT, and the - integer value stored at that index in the BAT gives the - index of the next block in the array (and thus the index of - the next BAT value). A special value is stored in the BAT - to indicate "end of file".
-The property table is essentially the directory - storage for the file system. It consists of the name of the - file or directory, its start block in both the file - system and BAT, and its actual size. The first - property in the property table is the root - element. It has two purposes: to be a directory entry - (the root of the directory tree, to be specific), and to - hold the start block for the small block data.
-Small block data is a special file that contains the data - for small files (less than 4K bytes). It subdivides its - blocks into smaller blocks and there is a special small - block allocation table that, like the main BAT for larger - files, is used to map a small file to its small blocks.
-The POIFS file system begins with a header
- block. The first 64 bits of the header form a long
- file type id or magic number identifier of
- 0xE11AB1A1E011CFD0L. This is basically a
- sanity check. If this isn't the first thing in the header
- (and consequently the file system) then this is not a
- POIFS file system and should be read with some other
- library.
It's important to know the most important parts of the - header. These are discussed in the rest of this - section.
-At offset 0x2C is an int specifying the number - of elements in the BAT array. The array at - 0x4C an array of ints. This array contains the - indices of every block in the Block Allocation - Table.
-Very large POIFS archives may have more blocks than can - be addressed by the BAT blocks enumerated in the header - block. How large? Well, the BAT array in the header can - contain up to 109 BAT block indices; each BAT block - references up to 128 blocks, and each block is 512 - bytes, so we're talking about 109 * 128 * 512 = - 6.8MB. That's a pretty respectable document! But, you - could have much more data than that, and in today's - world of cheap gigabyte drives, why not? So, the BAT - may be extended in that event. The integer value at - offset 0x44 of the header is the index of the - first extended BAT (XBAT) block. At offset - 0x48 of the header, there is an int value that - specifies how many XBAT blocks there are. The XBAT - blocks begin at the specified index into the array of - blocks making up the POIFS file system, and continue in - sequence for the specified count of XBAT blocks.
-Each XBAT block contains the indices of up to 128 BAT - blocks, so the document size can be expanded by another - 8MB for each XBAT block. The BAT blocks indexed by an - XBAT block are appended to the end of the list of BAT - blocks enumerated in the header block. Thus the BAT - blocks enumerated in the header block are BAT blocks 0 - through 108, the BAT blocks enumerated in the first - XBAT block are BAT blocks 109 through 236, the BAT - blocks enumerated in the second XBAT block are BAT - blocks 237 through 364, and so on.
-Through the use of XBAT blocks, the limit on the - overall document size is that imposed by the 4-byte - block indices; if the indices are unsigned ints, the - maximum file size is 2 terabytes, 1 terabyte if the - indices are treated as signed ints. Either way, I have - yet to see a disk drive large enough to accommodate - such a file on the shelves at the local office supply - stores.
-If a file contained in a POIFS archive is smaller than - 4096 bytes, it is stored in small blocks. Small blocks - are 64 bytes in length and are contained within big - blocks, up to 8 to a big block. As the main BAT is used - to navigate the array of big blocks, so the small - block allocation table is used to navigate the - array of small blocks. The SBAT's start block index is - found at offset 0x3C of the header block, and - remaining blocks constituting the SBAT are found by - walking the main BAT as if it were an ordinary file in - the POIFS file system (this process is described - below).
-An integer at address 0x30 specifies the start - index of the property table. This integer is specified - as a "block index". The Property Table - is stored, as is almost everything in a POIFS file - system, in big blocks and walked via the BAT. The - Property Table is described below.
-The property table is essentially nothing more than the - directory system. Properties are 128 byte records - contained within the 512 byte blocks. The first property - is always the Root Entry. The following applies to - individual properties within a property table:
-The Root Entry in the Property Table - contains the information necessary to read and write - small files, which are files less than 4096 bytes - long. The start block field of the Root Entry is the - start index of the Small Block Array, which is - read like any other file in the POIFS file system. Since - the SBAT cannot be used without the Small Block Array, - the Root Entry MUST be read or written using the Block - Allocation Table. The blocks making up the Small - Block Array are divided into 64-byte small blocks, up to - the size indicated in the Root Entry (which should always - be a multiple of 64).
-The individual properties form a directory tree, with the - Root Entry as the directory tree's root, as shown - in the accompanying drawing. Note the numbers in - parentheses in each node; they represent the node's index - in the array of properties. The NEXT_PROP, - PREVIOUS_PROP, and CHILD_PROP fields hold - these indices, and are used to navigate the tree.
-
- Each directory entry (i.e., a property whose type is - directory or root entry) uses its - CHILD_PROP field to point to one of its - subordinate (child) properties. It doesn't seem to matter - which of its children it points to. Thus in the previous - drawing, the Root Entry's CHILD_PROP field may contain 1, - 4, or the index of one of its other children. Similarly, - the directory node (index 1) may have, in its CHILD_PROP - field, 2, 3, or the index of one of its other - children.
-The children of a given directory property point to each - other in a similar fashion by using their - NEXT_PROP and PREVIOUS_PROP fields.
-Unused NEXT_PROP, PREVIOUS_PROP, and - CHILD_PROP fields contain the marker value of - -1. All file properties have a value of -1 for their - CHILD_PROP fields for example.
-The BAT blocks are pointed at by the bat array - contained in the header and supplemented, if necessary, - by the XBAT blocks. These blocks form a large - table of integers. These integers are block numbers. The - Block Allocation Table holds chains of integers. - These chains are terminated with -2. The elements in - these chains refer to blocks in the files. The starting - block of a file is NOT specified in the BAT. It is - specified by the property for a given file. The - elements in this BAT are both the block number (within - the file minus the header) and the number of the - next BAT element in the chain. This can be thought of as - a linked list of blocks. The BAT array contains the links - from one block to the next, including the end of chain - marker.
-Here's an example: Let's assume that the BAT begins as - follows:
-BAT[ 0 ] = 2
BAT[ 1 ] = 5
BAT[ 2 ] = 3
BAT[ 3 ] = 4
BAT[ 4 ] = 6
BAT[ 5 ] = -2
BAT[ 6 ] = 7
BAT[ 7 ] = -2
...
Now, if we have a file whose Property Table entry says it - begins with index 0, we walk the BAT array and see that - the file consists of blocks 0 (because the start block is - 0), 2 (because BAT[ 0 ] is 2), 3 (BAT[ 2 ] is 3), 4 (BAT[ - 3 ] is 4), 6 (BAT[ 4 ] is 6), and 7 (BAT[ 6 ] is 7). It - ends at block 7 because BAT[ 7 ] is -2, which is the end - of chain marker.
-Similarly, a file beginning at index 1 consists of - blocks 1 and 5.
-Other special numbers in a BAT array are:
-The following outlines the basic file system structures.
-| Field | -Description | -Offset | -Length | -Default value or const | -
| FILETYPE | -Magic number identifying this as a POIFS file - system. | -0x0000 | -Long | -0xE11AB1A1E011CFD0 | -
| UK1 | -Unknown constant | -0x0008 | -Integer | -0 | -
| UK2 | -Unknown Constant | -0x000C | -Integer | -0 | -
| UK3 | -Unknown Constant | -0x0014 | -Integer | -0 | -
| UK4 | -Unknown Constant (revision?) | -0x0018 | -Short | -0x003B | -
| UK5 | -Unknown Constant (version?) | -0x001A | -Short | -0x0003 | -
| UK6 | -Unknown Constant | -0x001C | -Short | --2 | -
| LOG_2_BIG_BLOCK_SIZE | -Log, base 2, of the big block size | -0x001E | -Short | -9 (2 ^ 9 = 512 bytes) | -
| LOG_2_SMALL_BLOCK_SIZE | -Log, base 2, of the small block size | -0x0020 | -Integer | -6 (2 ^ 6 = 64 bytes) | -
| UK7 | -Unknown Constant | -0x0024 | -Integer | -0 | -
| UK8 | -Unknown Constant | -0x0028 | -Integer | -0 | -
| BAT_COUNT | -Number of elements in the BAT array | -0x002C | -Integer | -required | -
| PROPERTIES_START | -Block index of the first block of the property - table | -0x0030 | -Integer | -required | -
| UK9 | -Unknown Constant | -0x0034 | -Integer | -0 | -
| UK10 | -Unknown Constant | -0x0038 | -Integer | -0x00001000 | -
| SBAT_START | -Block index of first big block containing the small - block allocation table (SBAT) | -0x003C | -Integer | --2 | -
| SBAT_Block_Count | -Number of big blocks holding the SBAT | -0x0040 | -Integer | -1 | -
| XBAT_START | -Block index of the first block in the Extended Block - Allocation Table (XBAT) | -0x0044 | -Integer | --2 | -
| XBAT_COUNT | -Number of elements in the Extended Block Allocation - Table (to be added to the BAT) | -0x0048 | -Integer | -0 | -
| BAT_ARRAY | -Array of block indices constituting the Block - Allocation Table (BAT) | -0x004C, 0x0050, 0x0054 ... 0x01FC | -Integer[] | --1 for unused elements, at least first element must - be filled. | -
| N/A | -Header block data not otherwise described in this - table | -N/A | -N/A | --1 | -
| Field | -Description | -Offset | -Length | -Default value or const | -
| BAT_ELEMENT | -Any given element in the BAT block | -0x0000, 0x0004, 0x0008, ... 0x01FC | -Integer | -
-
All other values point to the next element in the - chain and the next index of a block composing the - file. - |
-
| Field | -Description | -Offset | -Length | -Default value or const | -
| Properties[] | -This block contains the properties. | -0x0000, 0x0080, 0x0100, 0x0180 | -128 bytes | -All unused space is set to -1. | -
| Field | -Description | -Offset | -Length | -Default value or const | -
| NAME | -A unicode null-terminated uncompressed 16bit string - (lose the high bytes) containing the name of the - property. | -0x00, 0x02, 0x04, ... 0x3E | -Short[] | -0x0000 for unused elements, field required, 32 - (0x40) element max | -
| NAME_SIZE | -Number of characters in the NAME field | -0x40 | -Short | -Required | -
| PROPERTY_TYPE | -Property type (directory, file, or root) | -0x42 | -Byte | -1 (directory), 2 (file), or 5 (root entry) | -
| NODE_COLOR | -Node color | -0x43 | -Byte | -0 (red) or 1 (black) | -
| PREVIOUS_PROP | -Previous property index | -0x44 | -Integer | --1 | -
| NEXT_PROP | -Next property index | -0x48 | -Integer | --1 | -
| CHILD_PROP | -First child property index | -0x4c | -Integer | --1 | -
| SECONDS_1 | -Seconds component of the created timestamp? | -0x64 | -Integer | -0 | -
| DAYS_1 | -Days component of the created timestamp? | -0x68 | -Integer | -0 | -
| SECONDS_2 | -Seconds component of the modified timestamp? | -0x6C | -Integer | -0 | -
| DAYS_2 | -Days component of the modified timestamp? | -0x70 | -Integer | -0 | -
| START_BLOCK | -Starting block of the file, used as the first block - in the file and the pointer to the next block from - the BAT | -0x74 | -Integer | -Required | -
| SIZE | -Actual size of the file this property points - to. (used to truncate the blocks to the real - size). | -0x78 | -Integer | -0 | -
This document describes how to use the POIFS APIs to read, write, and modify files that employ a POIFS-compatible data structure to organize their content.
-This document is intended for Java developers who need to use the POIFS APIs to read, write, or modify files that employ a POIFS-compatible data structure to organize their content. It is not necessary for developers to understand the POIFS data structures, and an explanation of those data structures is beyond the scope of this document. It is expected that the members of the target audience will understand the rudiments of a hierarchical file system, and familiarity with the event pattern employed by Java APIs such as AWT would be helpful.
-This document attempts to be consistent in its terminology, which is defined here:
-| Term | -Definition | -
| Directory | -A special file that may contain other directories and documents. | -
| DirectoryEntry | -Representation of a directory within another directory. | -
| Document | -A file containing data, such as word processing data or a spreadsheet workbook. | -
| DocumentEntry | -Representation of a document within a directory. | -
| Entry | -Representation of a file in a directory. | -
| File | -A named entity, managed and contained by the file system. | -
| File System | -The POIFS data structures, plus the contained directories and documents, which are maintained in a hierarchical directory structure. | -
| Root Directory | -The directory at the base of a file system. All file systems have a root directory. The POIFS APIs will not allow the root directory to be removed or renamed, but it can be accessed for the purpose of reading its contents or adding files (directories and documents) to it. | -
This section covers reading a file system. There are two ways to read a file system; these techniques are sketched out in the following table, and then explained in greater depth in the sections following the table.
-| Technique | -Advantages | -Disadvantages | -
| Conventional Reading | -
-
|
-
-
|
-
| Event-Driven Reading | -
-
|
-
-
|
-
In this technique for reading, the entire file system is loaded into memory, and the entire directory tree can be walked by an application, reading specific documents at the application's leisure.
-Before an application can read a file from the file system, the file system needs to be loaded into memory. This is done by using the org.apache.poi.poifs.filesystem.POIFSFileSystem class. Once the file system has been loaded into memory, the application may need the root directory. The following code fragment will accomplish this preparation stage:
Assuming no exception was thrown, the file system can then be read.
-Note: loading the file system can take noticeable time, particularly for large file systems.
-Once the file system has been loaded into memory and the root directory has been obtained, the root directory can be read. The following code fragment shows how to read the entries in an org.apache.poi.poifs.filesystem.DirectoryEntry instance:
There are a couple of ways to read a document, depending on whether the document resides in the root directory or in another directory. Either way, you will obtain an org.apache.poi.poifs.filesystem.DocumentInputStream instance.
The DocumentInputStream class is a simple implementation of InputStream that makes a few guarantees worth noting:
-available() always returns the number of bytes in the document from your current position in the document.markSupported() returns true.mark(int limit) ignores the limit parameter; basically the method marks the current position in the document.reset() takes you back to the position when mark() was last called, or to the beginning of the document if mark() has not been called.skip(long n) will take you to your current position + n (but not past the end of the document).The behavior of available means you can read in a document in a single read call like this:
The combination of mark, reset, and skip provide the basic mechanisms needed for random access of the document contents.
If the document resides in the root directory, you can obtain a DocumentInputStream like this:
A more generic technique for reading a document is to obtain an org.apache.poi.poifs.filesystem.DirectoryEntry instance for the directory containing the desired document (recall that you can use getRoot() to obtain the root directory from its file system). From that DirectoryEntry, you can then obtain a DocumentInputStream like this:
The event-driven API for reading documents is a little more complicated and requires that your application know, in advance, which files it wants to read. The benefit of using this API is that each document is in memory just long enough for your application to read it, and documents that you never read at all are not in memory at all. When you're finished reading the documents you wanted, the file system has no data structures associated with it at all and can be discarded.
-The preparation phase involves creating an instance of org.apache.poi.poifs.eventfilesystem.POIFSReader and to then register one or more org.apache.poi.poifs.eventfilesystem.POIFSReaderListener instances with the POIFSReader.
org.apache.poi.poifs.eventfilesystem.POIFSReaderListener is an interface used to register for documents. When a matching document is read by the org.apache.poi.poifs.eventfilesystem.POIFSReader, the POIFSReaderListener instance receives an org.apache.poi.poifs.eventfilesystem.POIFSReaderEvent instance, which contains an open DocumentInputStream and information about the document.
A POIFSReaderListener instance can register for individual documents, or it can register for all documents; once it has registered for all documents, subsequent (and previous!) registration requests for individual documents are ignored. There is no way to unregister a POIFSReaderListener.
Thus, it is possible to register a single POIFSReaderListener for multiple documents - one, some, or all documents. It is guaranteed that a single POIFSReaderListener will receive exactly one notification per registered document. There is no guarantee as to the order in which it will receive notification of its documents, as future implementations of POIFSReader are free to change the algorithm for walking the file system's directory structure.
It is also permitted to register more than one POIFSReaderListener for the same document. There is no guarantee of ordering for notification of POIFSReaderListener instances that have registered for the same document when POIFSReader processes that document.
It is guaranteed that all notifications occur in the same thread. A future enhancement may be made to provide multi-threaded notifications, but such an enhancement would very probably be made in a new reader class, a ThreadedPOIFSReader perhaps.
The following table describes the three ways to register a POIFSReaderListener for a document or set of documents:
| Method Signature | -What it does | -
| registerListener(POIFSReaderListener listener) | -registers listener for all documents. | -
| registerListener(POIFSReaderListener listener, String name) | -registers listener for a document with the specified name in the root directory. | -
| registerListener(POIFSReaderListener listener, POIFSDocumentPath path, String name) | -registers listener for a document with the specified name in the directory described by path | -
The org.apache.poi.poifs.filesystem.POIFSDocumentPath class is used to describe a directory in a POIFS file system. Since there are no reserved characters in the name of a file in a POIFS file system, a more traditional string-based solution for describing a directory, with special characters delimiting the components of the directory name, is not feasible. The constructors for the class are used as follows:
| Constructor example | -Directory described | -
| new POIFSDocumentPath() | -The root directory. | -
| new POIFSDocumentPath(null) | -The root directory. | -
| new POIFSDocumentPath(new String[ 0 ]) | -The root directory. | -
| new POIFSDocumentPath(new String[ ] { "foo", "bar"} ) | -in Unix terminology, "/foo/bar". | -
| new POIFSDocumentPath(new POIFSDocumentPath(new String[] { "foo" }), new String[ ] { "fu", "bar"} ) | -in Unix terminology, "/foo/fu/bar". | -
Processing org.apache.poi.poifs.eventfilesystem.POIFSReaderEvent events is relatively easy. After all of the POIFSReaderListener instances have been registered with POIFSReader, the POIFSReader.read(InputStream stream) method is called.
Assuming that there are no problems with the data, as the POIFSReader processes the documents in the specified InputStream's data, it calls registered POIFSReaderListener instances' processPOIFSReaderEvent method with a POIFSReaderEvent instance.
The POIFSReaderEvent instance contains information to identify the document (a POIFSDocumentPath object to identify the directory that the document is in, and the document name), and an open DocumentInputStream instance from which to read the document.
Writing a file system is very much like reading a file system in that there are multiple ways to do so. You can load an existing file system into memory and modify it (removing files, renaming files) and/or add new files to it, and write it, or you can start with a new, empty file system:
-There are two restrictions on the names of files in a file system that must be considered when creating files:
-A document can be created by acquiring a DirectoryEntry and calling one of the two createDocument methods:
| Method Signature | -Advantages | -Disadvantages | -
| CreateDocument(String name, InputStream stream) | -
-
|
-
-
|
-
| CreateDocument(String name, int size, POIFSWriterListener writer) | -
-
|
-
-
|
-
Unlike reading, you don't have to choose between the in-memory and event-driven writing models; both can co-exist in the same file system.
-Writing is initiated when the POIFSFileSystem instance's writeFilesystem() method is called with an OutputStream to write to.
The event-driven model is quite similar to the event-driven model for reading, in that the file system calls your org.apache.poi.poifs.filesystem.POIFSWriterListener when it's time to write your document, just as the POIFSReader calls your POIFSReaderListener when it's time to read your document. Internally, when writeFilesystem() is called, the final POIFS data structures are created and are written to the specified OutputStream. When the file system needs to write a document out that was created with the event-driven model, it calls the POIFSWriterListener back, calling its processPOIFSWriterEvent() method, passing an org.apache.poi.poifs.filesystem.POIFSWriterEvent instance. This object contains the POIFSDocumentPath and name of the document, its size, and an open org.apache.poi.poifs.filesystem.DocumentOutputStream to which to write. A DocumentOutputStream is a wrapper over the OutputStream that was provided to the POIFSFileSystem to write to, and has the responsibility of making sure that the document your application writes fits within the size you specified for it.
Creating a directory is similar to creating a document, except that there's only one way to do so:
-As with reading documents, it is possible to create a new document or directory in the root directory by using convenience methods of POIFSFileSystem.
-| DirectoryEntry Method Signature | -POIFSFileSystem Method Signature | -
| createDocument(String name, InputStream stream) | -createDocument(InputStream stream, String name) | -
| createDocument(String name, int size, POIFSWriterListener writer) | -createDocument(String name, int size, POIFSWriterListener writer) | -
| createDirectory(String name) | -createDirectory(String name) | -
It is possible to modify an existing POIFS file system, whether it's one your application has loaded into memory, or one which you are creating on the fly.
-Removing a document is simple: you get the Entry corresponding to the document and call its delete() method. This is a boolean method, but should always return true, indicating that the operation succeeded.
Removing a directory is also simple: you get the Entry corresponding to the directory and call its delete() method. This is a boolean method, but, unlike deleting a document, may not always return true, indicating that the operation succeeded. Here are the reasons why the operation may fail:
isEmpty() on its DirectoryEntry; is the return value false?)Regardless of whether the file is a directory or a document, it can be renamed, with one exception - the root directory has a special name that is expected by the components of a major software vendor's office suite, and the POIFS API will not let that name be changed. Renaming is done by acquiring the file's corresponding Entry instance and calling its renameTo method, passing in the new name.
Like delete, renameTo returns true if the operation succeeded, otherwise false. Reasons for failure include these:
- This document describes the design of the POIFS system. It is - organized as follows: -
-- This document is written as part of an iterative process. - As that process is not yet complete, neither is this - document. -
-- The design of POIFS is not dependent on the code written - for the proof-of-concept prototype POIFS package. -
-- As usual, the primary considerations in the design of the - POIFS assumption involve the classic space-time tradeoff. - In this case, the main consideration has to involve - minimizing the memory footprint of POIFS. POIFS may be - called upon to create relatively large documents, and in - web application server, it may be called upon to create - several documents simultaneously, and it will likely - co-exist with other Serializer systems, competing with - those other systems for space on the server. -
-- We've addressed the risk of being too slow through a - proof-of-concept prototype. This prototype for POIFS - involved reading an existing file, decomposing it into its - constituent documents, composing a new POIFS from the - constituent documents, and writing the POIFS file back to - disk and verifying that the output file, while not - necessarily a byte-for-byte image of the input file, could - be read by the application that generated the input file. - This prototype proved to be quite fast, reading, - decomposing, and re-generating a large (300K) file in 2 to - 2.5 seconds. -
-- While the POIFS format allows great flexibility in laying - out the documents and the other internal data structures, - the layout of the filesystem will be kept as simple as - possible. -
-- The design of the POIFS is broken down into two parts: - discussion of the classes and - interfaces, and discussion of how - these classes and interfaces will be used to convert an - appropriate Java InputStream (such as an XML stream) to a - POIFS output stream containing an HSSF document. -
- Classes and Interfaces -- The classes and interfaces used in the POIFS are broken - down as follows: -
-| Package | -Contents | -
|---|---|
| net.sourceforge.poi.poifs.storage | -Block classes and interfaces | -
| net.sourceforge.poi.poifs.property | -Property classes and interfaces | -
| net.sourceforge.poi.poifs.filesystem | -Filesystem classes and interfaces | -
| net.sourceforge.poi.util | -Utility classes and interfaces | -
- The block classes and interfaces are shown - in the following class diagram. -
-
- 
-
| Class/Interface | -Description | -
|---|---|
| BATBlock | -The BATBlock class
- represents a single big block
- containing 128 BAT
- entries. Its - _fields array is
- used to read and write the BAT entries
- into the _data
- array.Its - createBATBlocks
- method is used to create an array of
- BATBlock instances from an array of
- int BAT entries.Its - calculateStorageRequirements
- method calculates the number of BAT
- blocks necessary to hold the specified
- number of BAT entries. |
-
| BigBlock | -The BigBlock class is an
- abstract class representing the common
- big block of 512 bytes. It implements
- BlockWritable,
- trivially delegating the
- writeBlocks method
- of BlockWritable to its own abstract
- writeData
- method. |
-
| BlockWritable | -The BlockWritable interface
- defines a single method,
- writeBlocks, that
- is used to write an implementation's
- block data to an
- OutputStream. |
-
| DocumentBlock | -The DocumentBlock class is
- used by a Document to holds
- its raw data. It also retains the
- number of bytes read, as this is used
- by the Document class to determine the
- total size of the data, and is also
- used internally to determine whether
- the block was filled by the
- InputStream or
- not.The - DocumentBlock
- constructor is passed an
- InputStream from which to
- fill its _data
- array.The size
- method returns the number of bytes
- read (_bytes_read
- when the instance was
- constructed.The - partiallyRead
- method returns true if the
- _data array was
- not completely filled, which may be
- interpreted by the Document as having
- reached the end of file
- point.Typical use of the - DocumentBlock class is like - this: while
- (true) |
-
| HeaderBlock | -The HeaderBlock class is
- used to contain the data found in a
- POIFS header. Its IntegerField - members are used to read and write the - appropriate entries into the - _data
- array.Its - setBATBlocks,
- setPropertyStart,
- and setXBATStart
- methods are used to set the
- appropriate fields in the
- _data
- array.The - calculateXBATStorageRequirements
- method is used to determine how many
- XBAT blocks are necessary to
- accommodate the specified number of
- BAT blocks.
- |
-
| PropertyBlock | -The PropertyBlock class is
- used to contain Property
- instances for the PropertyTable
- class. It contains an array, - _properties of 4
- Property instances, which together
- comprise the 512 bytes of a BigBlock.The - createPropertyBlockArray
- method is used to convert a
- List of Property
- instances into an array of
- PropertyBlock instances. The number of
- Property instances is rounded up to a
- multiple of 4 by creating empty
- anonymous inner class extensions of
- Property. |
-
- The property classes and interfaces are - shown in the following class diagram. -
-
- 
-
| Class/Interface | -Description | -
|---|---|
| Directory | -The Directory interface is
- implemented by the RootProperty
- class. It is not strictly necessary
- for the initial POIFS implementation,
- but when the POIFS supports directory
- elements, this interface will be
- more widely implemented, and so is
- included in the design at this point
- to ease the eventual support of
- directory elements. Its methods are - a getter/setter pair, - getChildren,
- returning an Iterator of
- Property
- instances; and
- addChild, which
- will allow the caller to add another
- Property instance to the Directory's
- children. |
-
| DocumentProperty | -The DocumentProperty class
- is a trivial extension of Property and is
- used by Document to keep
- track of its associated entry in the
- PropertyTable. Its - constructor takes a name and the - document size, on the assumption that - the Document will not create a - DocumentProperty until after it has - created the storage for the document - data and therefore knows how much data - there is. |
-
| File | -The File interface - specifies the behavior of reading and - writing the next and previous child - fields of a Property. | -
| Property | -The Property class is an
- abstract class that defines the basic
- data structure of an element of the Property
- Table. Its ByteField, ShortField, and - IntegerField - members are used to read and write - data into the appropriate locations in - the _raw_data
- array.The - _index member is
- used to hold a Propery instance's
- index in the List of
- Property instances maintained by PropertyTable,
- which is used to populate the child
- property of parent Directory
- properties and the next property and
- previous property of sibling File
- properties.The - _name,
- _next_file, and
- _previous_file
- members are used to help fill the
- appropriate fields of the _raw_data
- array.Setters are provided for - some of the fields (name, property - type, node color, child property, - size, index, start block), as well as - a few getters (index, child - property). The - preWrite method is
- abstract and is used by the owning
- PropertyTable to iterate through its
- Property instances and prepare each
- for writing.The - shouldUseSmallBlocks
- method returns true if the Property's
- size is sufficiently small - how small
- is none of the caller's business.
- |
-
| PropertyBlock | -See the description in PropertyBlock. | -
| PropertyTable | -The PropertyTable class
- holds all of the DocumentProperty
- instances and the RootProperty
- instance for a Filesystem
- instance. It maintains a - List of its Property
- instances
- (_properties), and
- when prepared to write its data by a
- call to preWrite,
- it gets and holds an array of PropertyBlock
- instances
- (_blocks.It - also maintains its start block in its - _start_block
- member.It has a method, - getRoot, to get
- the RootProperty, returning it as an
- implementation of Directory, and a
- method to add a Property,
- addProperty, and a
- method to get its start block,
- getStartBlock. |
-
| RootProperty | -The RootProperty class acts
- as the Directory for
- all of the DocumentProperty
- instance. As such, it is more of a
- pure directory
- entry than a proper root
- entry in the Property
- Table, but the initial POIFS
- implementation does not warrant the
- additional complexity of a full-blown
- root entry, and so it is not modeled
- in this design. It maintains a - List of its children,
- _children, in
- order to perform its
- directory-oriented duties. |
-
- The property classes and interfaces are - shown in the following class diagram. -
-
- 
-
| Class/Interface | -Description | -
|---|---|
| Filesystem | -The Filesystem class is the
- top-level class that manages the
- creation of a POIFS document. It - maintains a PropertyTable - instance in its - _property_table
- member, a HeaderBlock
- instance in its
- _header_block
- member, and a List of its
- Document
- instances in its
- _documents
- member.It provides methods for a - client to create a document - ( createDocument),
- and a method to write the Filesystem
- to an OutputStream
- (writeFilesystem). |
-
| BATBlock | -See the description in BATBlock | -
| BATManaged | -The BATManaged interface
- defines common behavior for objects
- whose location in the written file is
- managed by the Block
- Allocation Table. It defines - methods to get a count of the - implementation's BigBlock - instances - ( countBlocks), and
- to set an implementation's start block
- (setStartBlock). |
-
| BlockAllocationTable | -The BlockAllocationTable is
- an implementation of the POIFS Block
- Allocation Table. It is only
- created when the Filesystem is
- about to be written to an
- OutputStream.It - contains an IntList of block - numbers for all of the BATManaged - implementations owned by the - Filesystem, - _entries, which is
- filled by calls to
- allocateSpace.It - fills its array, - _blocks, of BATBlock
- instances when its
- createBATBlocks
- method is called. This method has to
- take into account its own storage
- requirements, as well as those of the
- XBAT blocks, and so calls
- BATBlock.calculateStorageRequirements
- and
- HeaderBlock.calculateXBATStorageRequirements
- repeatedly until the counts returned
- by those methods stabilize.The - countBlocks method
- returns the number of BATBlock
- instances created by the preceding
- call to createBlocks. |
-
| BlockWritable | -See the description in BlockWritable | -
| Document | -The Document class is used
- to contain a document, such as an HSSF
- workbook. It has its own DocumentProperty - ( _property) and
- stores its data in a collection of DocumentBlock
- instances
- (_blocks).It - has a method, - getDocumentProperty,
- to get its DocumentProperty. |
-
| DocumentBlock | -See the description in DocumentBlock | -
| DocumentProperty | -See the description in DocumentProperty | -
| HeaderBlock | -See the description in HeaderBlock | -
| PropertyTable | -See the description in PropertyTable | -
- The utility classes and interfaces are - shown in the following class diagram. -
-
- 
-
| Class/Interface | -Description | -
|---|---|
| BitField | -The BitField class is used - primarily by HSSF code to manage - bit-mapped fields of HSSF records. It - is not likely to be used in the POIFS - code itself and is only included here - for the sake of complete documentation - of the POI utility classes. | -
| ByteField | -The ByteField class is an
- implementation of FixedField for
- the purpose of managing reading and
- writing to a byte-wide field in an
- array of bytes. |
-
| FixedField | -The FixedField interface
- defines a set of methods for reading a
- field from an array of
- bytes or from an
- InputStream, and for
- writing a field to an array of
- bytes. Implementations
- typically require an offset in their
- constructors that, for the purposes of
- reading and writing to an array of
- bytes, makes sure that
- the correct bytes in the
- array are read or written. |
-
| HexDump | -The HexDump class is a
- debugging class that can be used to
- dump an array of bytes to
- an OutputStream. The
- static method dump
- takes an array of bytes,
- a long offset that is
- used to label the output, an open
- OutputStream, and an
- int index that specifies
- the starting index within the array of
- bytes.The data is - displayed 16 bytes per line, with each - byte displayed in hexadecimal format - and again in printable form, if - possible (a byte is considered - printable if its value is in the range - of 32 ... 126). Here is an example - of a small array of bytes
- with an offset of
- 0x110:00000110 C8 00 00 00 FF 7F 90 01 00 00 00 00 00 00 05 01 ................ |
-
| IntegerField | -The IntegerField class is
- an implementation of FixedField for
- the purpose of managing reading and
- writing to an integer-wide field in an
- array of bytes. |
-
| IntList | -The IntList class is a
- work-around for functionality missing
- in Java (see http://developer.java.sun.com/developer/bugParade/bugs/4487555.html
- for details); it is a simple growable
- array of ints that gets
- around the requirement of wrapping and
- unwrapping ints in
- Integer instances in
- order to use the
- java.util.List
- interface.IntList mimics - the functionality of the - java.util.List interface
- as much as possible. |
-
| LittleEndian | -The LittleEndian class
- provides a set of static methods for
- reading and writing
- shorts,
- ints, longs,
- and doubles in and out of
- byte arrays, and out of
- InputStreams, preserving
- the Intel byte ordering and encoding
- of these values. |
-
| LittleEndianConsts | -The LittleEndianConsts
- interface defines the width of a
- short, int,
- long, and
- double as stored by Intel
- processors. |
-
| LongField | -The LongField class is an
- implementation of FixedField for
- the purpose of managing reading and
- writing to a long-wide field in an
- array of bytes. |
-
| ShortField | -The ShortField class is an
- implementation of FixedField for
- the purpose of managing reading and
- writing to a short-wide field in an
- array of bytes. |
-
| ShortList | -The ShortList class is a
- work-around for functionality missing
- in Java (see http://developer.java.sun.com/developer/bugParade/bugs/4487555.html
- for details); it is a simple growable
- array of shorts that gets
- around the requirement of wrapping and
- unwrapping shorts in
- Short instances in order
- to use the java.util.List
- interface.ShortList mimics - the functionality of the - java.util.List interface
- as much as possible. |
-
| StringUtil | -The StringUtil class - manages the processing of Unicode - strings. | -
- This section describes the scenarios of how the - POIFS classes and interfaces will be used to - convert an appropriate XML stream to a POIFS - output stream containing an HSSF document. -
-- It is broken down as suggested by the following - scenario diagram: -
-
- 
-
| Step | -Description | -
|---|---|
| 1 | -The Filesystem is - created by the client application. | -
| 2 | -The client
- application tells the Filesystem to create a
- document, providing an
- InputStream and the name of the
- document. This may be repeated several
- times. |
-
| 3 | -The client
- application asks the Filesystem to write its
- data to an OutputStream. |
-
- Initialization -
-- Initialization of the POIFS system is - shown in the following scenario diagram: -
-
- 
-
| Step | -Description | -
|---|---|
| 1 | -The Filesystem - object, which is created for each - request to convert an appropriate XML - stream to a POIFS output stream - containing an HSSF document, creates - its PropertyTable. | -
| 2 | -The PropertyTable
- creates its RootProperty
- instance, making the RootProperty the
- first Property
- in its List of Property
- instances. |
-
| 3 | -The Filesystem - creates its HeaderBlock - instance. It should be noted that the - decision to create the HeaderBlock at - Filesystem initialization is - arbitrary; creation of the HeaderBlock - could easily and harmlessly be - postponed to the appropriate moment in - writing the - filesystem. | -
- Creating and adding a document to a POIFS - system is shown in the following scenario - diagram: -
-
- 
-
| Step | -Description | -
|---|---|
| 1 | -The Filesystem
- instance creates a new Document
- instance. It will store the newly
- created Document in a
- List of BATManaged
- instances. |
-
| 2 | -The Document reads
- data from the provided
- InputStream, storing the
- data in DocumentBlock
- instances. It keeps track of the byte
- count as it reads the data. |
-
| 3 | -The Document creates - a DocumentProperty - to keep track of its property - data. The byte count is stored in the - newly created DocumentProperty - instance. | -
| 4 | -The Filesystem - requests the newly created DocumentProperty - from the newly created Document - instance. | -
| 5 | -The Filesystem
- sends the newly created DocumentProperty
- to the Filesystem's PropertyTable
- so that the PropertyTable can add the
- DocumentProperty to its
- List of Property
- instances. |
-
| 6 | -The Filesystem gets - the RootProperty - from its PropertyTable. | -
| 7 | -The Filesystem adds - the newly created DocumentProperty - to the RootProperty. | -
- Although typical deployment of the POIFS - system will only entail adding a single Document (the - workbook) to the Filesystem, there - is nothing in the design to prevent - multiple Documents from being added to the - Filesystem. This flexibility can be - employed to write summary information - document(s) in addition to the workbook. -
-- Writing the filesystem is shown in the - following scenario diagram: -
-
- 
-
| Step | -Description | -|
|---|---|---|
| 1 | -The Filesystem adds
- the PropertyTable
- to its List of BATManaged
- instances and calls the
- PropertyTable's
- preWrite
- method. The action taken by the
- PropertyTable is shown in the PropertyTable
- preWrite scenario diagram. |
- |
| 2 | -The Filesystem - creates the BlockAllocationTable. | -|
| 3 | -The Filesystem gets - the block count from the BATManaged - instance. | These three steps are
- repeated for each BATManaged
- instance in the Filesystem's
- List of BATManaged
- instances (i.e., the Documents, in
- order of their addition to the
- Filesystem, followed by the PropertyTable). |
-
| 4 | -The Filesystem - sends the block count to the BlockAllocationTable, - which adds the appropriate entries to - is IntList of - entries, returning the starting block - for the newly added entries. | -|
| 5 | -The Filesystem - gives the start block number to the BATManaged - instance. If the BATManaged instance - is a Document, - it sets the start block field in its - DocumentProperty. | -|
| 6 | -The Filesystem - tells the BlockAllocationTable - to create its BatBlocks. | -|
| 7 | -The Filesystem - gives the BAT information to the HeaderBlock so - that it can set its BAT fields and, if - necessary, create XBAT blocks. | -|
| 8 | -If the filesystem is - unusually large (over 7MB), the - HeaderBlock - will create XBAT blocks to contain the - BAT data that it cannot hold - directly. In this case, the Filesystem - tells the HeaderBlock where those - additional blocks will be stored. | -|
| 9 | -The Filesystem - gives the PropertyTable - start block to the HeaderBlock. | -|
| 10 | -The Filesystem
- tells the BlockWritable
- instance to write its blocks to the
- provided
- OutputStream.This - step is repeated for each - BlockWritable instance, in this - order: -
|
- |
- PropertyTable - preWrite scenario diagram -
-
- 
-
| Step | -Description | -
|---|---|
| 1 | -The PropertyTable
- calls setIndex for
- each of its Property
- instances, so that each Property now
- knows its index within the
- PropertyTable's List of
- Property instances. |
-
| 2 | The PropertyTable - requests the PropertyBlock - class to create an array of PropertyBlock - instances. | -
| 3 | - -The PropertyBlock
- calculates the number of empty Property
- instances it needs to create and
- creates them. The algorithm for the
- number to create is: - block_count = (properties.size()
- + 3) / 4; |
-
| 4 | The PropertyBlock
- creates the required number of PropertyBlock
- instances from the List
- of Property
- instances, including the newly created
- empty Property
- instances. |
-
| 5 | -The PropertyTable
- calls preWrite on
- each of its Property
- instances. For DocumentProperty
- instances, this call is a no-op. For
- the RootProperty,
- the action taken is shown in the RootProperty
- preWrite scenario diagram. |
-
- RootProperty - preWrite scenario diagram -
-
- 
-
| Step | -Description | -|
|---|---|---|
| 1 | -The RootProperty
- sets its child property with the index
- of the child Property that is
- first in its List of
- children. |
- |
| 2 | -The RootProperty
- sets its child's next property field
- with the index of the child's next
- sibling in the RootProperty's
- List of children. If the
- child is the last in the
- List, its next property
- field is set to -1. |
- These two steps are
- repeated for each File in the RootProperty's
- List of
- children. |
-
| 3 | -The RootProperty
- sets its child's previous property
- field with a value of
- -1. |
- |
POIFS is a pure Java implementation of the OLE 2 Compound - Document format.
-By definition, all APIs developed by the POI project are - based somehow on the POIFS API.
-A common confusion is on just what POIFS buys you or what OLE - 2 Compound Document format is exactly. POIFS does not buy you - DOC, or XLS, but is necessary to generate or read DOC or XLS - files. You see, all file formats based on the OLE 2 Compound - Document Format have a common structure. The OLE 2 Compound - Document Format is essentially a convoluted archive - format. Think of POIFS as a "zip" library. Once you can get - the data in a zip file you still need to interpret the - data. As a general rule, while all of our formats use - POIFS, most of them attempt to abstract you from it. There - are some circumstances where this is not possible, but as a - general rule this is true.
-If you're an end user type just looking to generate XLS - files, then you'd be looking for HSSF not POIFS; however, if - you have legacy code that uses MFC property sets, POIFS is - for you! Regardless, you may or may not need to know how to - use POIFS but ultimately if you use technologies that come - from the POI project, you're using POIFS underneith. Perhaps - we should have a branding campaign "POIFS Inside!". ;-)
- -| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -None | -
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -
-
|
-
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -
-
or -
|
-
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -
-
|
-
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -None | -
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -None | -
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -
- Either -
or -
|
-
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -
-
|
-
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -
- Either -
or -
|
-
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -
-
|
-
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -The specified file does not yet exist in the file - system | -
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -
-
|
-
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -
-
|
-
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -1a. POIFS throws an exception if no file with the - specified name exists. | -
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -The file system has been read (use case 1, read - existing file system) or created (use case 3, create - new file system) | -
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -None | -
| Primary Actor: | -POIFS | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -None | -
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -3a. An exception will be thrown if the specified Block - Allocation Table is corrupt, as evidenced by an index - pointing to a non-existent block, or by a chain - extending past the known size of the file. | -
| Primary Actor: | -POIFS client | -
| Scope: | -POIFS | -
| Level: | -Summary | -
| Stakeholders and Interests: | -
-
|
-
| Precondition: | -
-
|
-
| Minimal Guarantee: | -None | -
| Main Success Guarantee: | -
-
|
-
| Extensions: | -
-
|
-
Currently we don't have any sites listed that use Poi, but we're sure they're out there. - Help us change this. If you've - written a site that utilises Poi let us know. -
- -Publically available products/projects using POI include: -
-- Every project on Jakarta has resolutions that they vote on. - Decisions are made, etc. But what happens once those decisions - are made? They are archived in the mail list archive never to - be read again (once its not in the top 10 or so posts). So they - get discussed again and again. -
-- Rather than have that big waste of time, we have this section to - record important POI decisions. Once a decision is passed it - need only be linked to this page (either by creating a page for - it or by simply linking it to the archive messages). Wherever - possible a brief about how many votes for and against an maybe - some background should be posted. -
-- This section is intended mainly to reduce big waste of time - discussions from taking away from whats important...developing - POI! :-D -
-- As the POI project has grown the "styles" used have become more - varied, some see this as a bad thing, but in reality it - can be a good thing. Each can learn from the different - styles by working with different code. That being said - there are some universal "good quality" guidelines that - must be adopted on a project of any proportions. -
-- Marc Johnson Authored the following resolution: -
-- On Tue, 2002-01-08 at 22:23, Marc Johnson wrote: - Standards are wonderful; everyone should have a set. - Here's what I propose for coding standards for POI WRT comments (should I - feel the need, I'll post more of these little gems): -
-- As opposed to the formerly used POI License which was - based on the Apache Public License, now that POI is part of - Jakarta, use the APL 1.1 for the header. Currently, the - Apache Software Foundation requires us to use the full - long version. -
-- Tip: No laughing or joking allowed in conversations regarding coding - standards. - Any mail on coding standards will be treated very seriously, - and sent here with a RTFM. -
-- The motion was passed unanimously with no negative or - neutral votes. -
-- Andy didn't feel like going through his mail and sucking - out the comments.. If there is anything you feel should - be added here do it yourself ;-). -
-- Das POI-Übersetzungsprojekt hat begonnen. - Den Anfang machen spanisch, - japanisch - und deutsch. Andere Sprachen sind herzlich willkommen. - Machen Sie mit! -
-- Die Wahl für das POI-Logo ist beendet. Danke für Ihre Stimmen. -
- - - -- Das POI-Projekt besteht aus Java-APIs zum Erstellen und - Bearbeiten von Dateiformaten, die auf dem Microsoft-Dateiformat »OLE-2 - Compound Document« beruhen. Dateien in diesem Format sind unter - anderem die meisten Microsoft-Office-Dateien, wie zum - Beispiel Excel- und Word-Dateien. -
-- Grundsätzlich versuchen wir, möglichst viel mit anderen Projekten - zusammenzuarbeiten, um die gewünschten Funktionalitäten zur Verfügung - zu stellen. Einige Beispiele: Für - Cocoon - werden bald Generatoren und Serializer zur Verfügung stehen. Wir - arbeiten mit - Open Office.org - zusammen, um das Excel-Dateiformat zu - dokumentieren. - Für Lucene - werden bald Filtermodule zur Verfügung stehen. Wir stellen anderen - Projekten Teile des POI-Projektes zur Verfügung, damit diese - die POI-Funktionalitäten nutzen können. -
-- Wir werden diese Frage komponentenweise beantworten. POI besteht aus - einer Reihe von Komponenten, die jeweils unterschiedliche Probleme - angehen. Das Kürzel »POI« steht für das gesamte Projekt. -
-- Mit POIFS können Sie Dateien oder Dokumente, die im - OLE 2 Compound Document Format geschrieben wurden, mit Java - einlesen. Solche Dateien werden üblicherweise mit der - MFC-Klassenbibliothek erzeugt. - Außerdem können sie POIFS nutzen, um Dateien im OLE 2 Compound - Document Format zu schreiben. Damit können sie zum Beispiel - den Datenaustausch mit der Windows-Plattform sicherstellen. - Wir können guten Gewissens behaupten, daß POIFS die - vollständigste Implementierung dieses Dateiformates ist. -
-- Mit HSSF können sie Excel-Dateien in Java lesen und - schreiben. Sie können auch Excel-Tabellen lesen und - modifizieren. Allerdings ist die Schreibfunktionalität im Moment am - ausgereiftesten. -
-- POI bedeutet »Poor Obfuscation Implementation« (Schlechte, - verschleiernde Implementierung). - Warum geben wir unserem Projekt einen so abschätzigen Namen? - Nun, das Microsoft OLE 2 Compound Document Format ist einfach - schlecht durchdacht. Von seiner Grundidee her ist es ein - Dateiarchiv mit einer Struktur, die dem alten DOS-FAT-Dateisystem - ähnelt. Die Redmonder haben kein bereits vorhandenes Archivformat - wie tar, gzip, zip oder arc genutzt, sondern stattdessen ein - eigenes Archivformat erfunden, - das keinerlei Standardverschlüsselung oder -komprimierung - bietet, das schlecht erweiterbar ist, und das zur - Fragmentierung neigt. -
-Poi ist außerdem eine Spezialität der hawaiianischen Küche. Sie wird - in Merriam Webster's - Dictionary beschrieben als: »Ein hawaiianisches Gericht aus - Taro-Wurzeln, die durch Stampfen, Kochen und Kneten zu einer Paste - geformt und oft noch ein wenig gegoren wird.« Dies ist witzigerweise - eine treffende Beschreibung des Dateiformats.
-- POI ist also eine Abkürzung. Wenn Sie Abkürzungen nicht mögen, - dann denken sie einfach bei Poi an das hawaiianischen Gericht. - Je nachdem, ob Sie Abkürzungen mögen oder nicht, nutzen sie - einfach POI oder Poi, wenn sie dieses Projekt meinen. -
-- POI besteht aus mehreren Komponenten, die jeweils unterschiedliche - Aufgaben angehen. Beispielsweise dient die Komponente HSSF dazu, - Excel-Dateien zu schreiben und zu lesen. Es folgt eine Liste aller - Komponenten des POI-Projektes mit einer sehr kurzen Zusammenfassung - ihres Zweckes. -
-- POIFS ist der älteste und stabilste Teil des Projektes. POIFS - ist unsere Portierung des OLE 2 Compound Document Formats - in reinem Java. Es unterstützt Lesen und Schreiben. Alle - anderen Komponenten basieren auf POIFS. Mehr Informationen - gibt es auf der POIFS-Seite. -
-- HSSF ist unsere Portierung des Microsoft Excel 97(-2002) - Dateiformats in reinem Java. Es unterstützt Lesen und - Schreiben. Mehr Informationen gibt es auf der - HSSF-Seite. -
-- HDF ist unsere Portierung des Microsoft Word 97 Datei-Formats - in reinem Java. Es unterstützt Lesen und Schreiben. Mehr - Informationen gibt es auf der - HDF-Seite. - Diese Komponente ist noch nicht sehr weit fortgeschritten. Wir suchen - Entwickler, die mitmachen. -
-- HPSF ist unsere Portierung des OLE 2 Property Formats. - Property Sets werden häufig genutzt, um Metadaten eines - Dokuments wie Titel, Autor und Datum zu speichern. Sie - können aber auch für applikationsspezifische Anwendungen - genutzt werden. Mehr Informationen gibt es auf der - HPSF-Seite. -
-- Der HSSF-Serializer war Teil der Version 1.0 und der letzten Versionen - von Sourceforge. - Er wurde an das Cocoon-Projekt - übertragen und ist Bestandteil von Cocoon seit Version 2.0.2. -
-- Sie möchten zu diesem Projekt beitragen? Hervorragend! - Wir brauchen immer begeisterte, fleißige und talentierte Leute, die - uns bei den verschiedenen Aufgaben des Projektes helfen. Nummer eins - sind Fehlerberichte und Vorschläge für neue Funktionen. Nummer zwei - ist die Dokumentation.
-Egal, ob sie Kritik oder Vorschläge haben, - oder ob Sie Beiträge in Form von Code oder Dokumentation liefern - möchten, immer werden Sie bei uns ein offenes Ohr - finden. Und nicht zuletzt brauchen wir Java-Programmierer, die - sich durch die zahlreichen Ecken und Kanten der Microsoft-Dateiformate - hindurchwühlen und uns dabei helfen, diese Formate auf die - Java-Plattform zu portieren. -
-- Wenn Sie motiviert sind und Zeit haben, tragen Sie sich - in unsere Mailing-Listen ein, und machen sie mit! Bei der Einarbeitung - helfen wir Ihnen gerne. -
-- Vea Cómo contribuir a Poi. -
- -
- No es que estos tengan, necesariamente, suficiente calidad como para ser incluidos
- en el núcleo de la distribución, pero han sido probados bajo contrib/.
-
- ¡Ninguno Todavía! - aunque pude esperarse que algunos de los enlaces - listados a continuación lleguen eventualmente a migrarse al nivel de "componentes contribuidos", - y posteriormente incluso a la mismísima distribución principal. -
-Entregas de modificaciones (Submissions of modifications) - a Poi que esperan revisión. Cualquiera puede realizar comentarios sobre ellas en la lista - de desarrollo - ¡se necesitan revisores del código! - Su utilización cae bajo su responsabilidad - aunque Poi no puede garantizarlo, - estos parches no han sido revisados, cuando menos aceptados. -
-Las otras extensiones listadas aquí tampoco están respaldadas - por el proyecto Poi - se proporcionan sólo por comodidad. Pueden funcionar o no, - pueden ser de código abierto o no, etc. -
- -Para añadir un enlace a esta tabla, ver Cómo contribuir - a POI.
- -| Nombre y Enlace | -Tipo | -Descripción | -Estado | -Licencia | -Contacto | -
|---|
- A number of people are using POI for a variety of purposes. As with - any new API or technology, the first question people generally ask - is not "how can I" but rather "Who else is doing what I'm about to - do?" This is understandable with the abismal success rate in the - software business. These case statements are meant to help create - confidence and understanding. -
-- We are actively seeking case studies for this page (after all it - just started). Andy Oliver (acoliver at apache dot org) has - agreed to have a few T-Shirts printed with the POI logo (once its - chosen) for the first - few best submissions. To submit a case study, either - - submit a patch for this page (preferred) or email it to the - mailing list - . -
-- Edwards and Kelcey Technology (http://www.ekcorp.com/) developed a - Facility - Managament and Maintenance System for the Telecommunications industry - based - on Turbine and Velocity. Originally the invoicing was done with a simple - CVS - sheet which was then marked up by accounts and customized for each client. - As growth has been consistent with the application, the requirement for - invoices that need not be touched by hand increased. POI provided the - solution to this issue, integrating easily and transparently into the - system. POI HSSF was used to create the invoices directly from the server - in - Excel 97 format and now services over 150 unique invoices per month. -
-- Cameron Riley (crileyNO@ SPAMekmail.com) -
-- Probablemente hayas habilitado el registro (logging). Dicho registro es - una herramienta útil para la búsqueda de errores (debug). Tenerlo habilitado - reducirá el rendimiento en un factor de al menos 100. El registro es útil para - comprender por qué POI no puede leer algún fichero o para el propio desarrollo - de POI. - Los errores importantes se lanzan como excepciones, lo cual significa que - probablemente no necesites el registro (log). -
-El paquete "eventmodel" de HSSF es un nuevo API para la lectura más eficiente de ficheros - XML. Requiere mayor conocimiento por parte del usuario, pero reduce el consumo de memoria a - una décima parte. Está basado en el modelo de eventos AWT en combinación con SAX. Si necesita - acceso de sólo-lectura a un fichero XML determinado, esta es la mejor manera de hacerlo.
-Star Office 5.1 escribe algunos registros utilizando el viejo estándar BIFF. - Esto provoca algunos problemas con POI que sólo soporta BIFF8.
-Es posible que su hoja de cálculo contenga alguna característica que no esté - soportada actualmente por HSSF. Por ejemplo - hojas de cálculo que contengan - celdas con formato RTF (rich text) no están soportadas actualmente.
-Al proteger una hoja de cálculo, ésta se cifra. No tocaremos el cifrado, porque no - tenemos el suficiente conocimiento legal y no estamos seguros de las implicaciones que - conllevaría el intentar implementar esto. Si desea intentarlo, es libre de hacerlo y - de añadirlo como un módulo enchufable (plugin). Sin embargo, no lo guardaremos aquí.
-Excel almacena las fechas como números. Así la única manera para determinar - si una celda está realmente almacenada como una fecha consiste en mirar su formato. - Hay un método de ayuda (helper) en HSSFDateUtil (desde la distribución 1.7.0-dev) - que lo comprueba. Gracias a Jason Hoffman por proporcionar la solución.
-- El problema normalmente se manifiesta como un montón de caracteres basura - en la pantalla. El problema persiste incluso aunque hayas configurado el tipo mime - correcto. -
-- La respuesta breve es: no dependas de IE para mostrar un fichero binario. - Escribe un documento adjunto como es debido si lo envías a través de un servlet. - Toda versión de IE tiene diferentes fallos (bugs) en este sentido. -
-- El problema en la mayoría de las versiones de IE reside en que no utiliza el tipo mime - de la respuesta HTTP para determinar el tipo de fichero; en su lugar utiliza la extensión - del fichero en la petición. Así podría añadir un .xls a su cadena de petición. - Por ejemplo: http://yourserver.com/myServelet.xls?param1=xx. Esto se consigue - fácilmente a través del mapeo de URL en cualquier contenedor servlet. A veces una - petición como - http://yourserver.com/myServelet?param1=xx&dummy=file.xls - también funciona. -
-- Para garantizar la correcta apertura del fichero en Excel desde IE, escribe - tu fichero a un fichero temporal bajo su raiz web desde tu servlet. Envía entonces - una respuesta http al navegador para que haga una redirección en el lado del cliente - a tu fichero temporal. (Si haces una redirección en el lado del servidor utilizando - RequestDispatcher, tendrás que añadir .xls a la petición como se ha mendionado más - arriba) -
-- Date cuenta de que cuando pides un documento que se abre con un manejador externo, - IE a veces realiza dos peticiones al servidor web. Así que si tu proceso generador - es pesado, tiene sentido escribir a un fichero temporal, para que peticiones - múltiples utilicen el fichero estático. -
-- Nada de esto pertenece a Excel. El mismo problema ocurre cuando intentas general - cualquier fichero binario dinámicamente a un cliente IE. Por ejemplo, si generas - ficheros pdf utilizando - FOP, - te encontrarás con los mismos problemas. -
- -- HSSF no soporta todavía formatos de datos personalizados, sin embargo, - debería ser una facilidad razonablemente sencilla de añadir y aceptaremos - gustosos contribuciones en este área. -
-- Estos son los formatos incluidos que soporta: -
-- http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFDataFormat_java.html#HSSFDataFormat -
-- Añade celdas vacías alrededor de donde las celdas hubieran estado normalmente y - configura los bordes individualmente para cada celda. - Probablemente mejoraremos HSSF en el futuro para facilitar este proceso. -
-- Por defecto HSSF utiliza valores de celdas y nombres de hoja en unicode comprimido, - asi que para soportar la localización deberías utilizar Unicode. - Para hacerlo deberías configurarlo manualmente: -
-- Asegúrate de que haces la llamada a setEncoding() antes de llamar a setCellValue(), - si no, lo que le pases no será interpretado correctamente. -
-- El proyecto POI se gestó tiempo atrás, cerca de abril de 2001, - cuando Andy Oliver obtuvo un contrato de corta duración para realizar - informes Excel basados en Java. Ya había realizado este proyecto unas - cuantas veces antes, y sabía exactamente dónde buscar las herramientas - que necesitaría. - Irónicamente, el API que solía utilizar se había disparado en precio - desde unos $300 ($US) hasta unos $10K ($US). Calculó que a dos personas - les llevaría unos seis meses el portar Excel así que le recomendó al - cliente que pagase los $10K. -
- -- Cerca de junio de 2001, Andy empezó a pensar lo genial que sería - tener una herramienta Java de código abierto para hacer esto y, - mientras tuvo algo de tiempo libre, comenzó el proyecto y aprendió - cosas sobre el Formato de Documento Compuesto OLE2. Tras chocarse - con varios obstáculos insalvables, se dio cuenta de que necesitaría ayuda. - Publicó un mensaje en su Grupo de Usuarios Java local (JUG) y - preguntó si alguien estaba interesado. Tuvo mucha suerte y el - programador Java de mayor talento que había conocido nunca, - Marc Johnson, se unió al proyecto. A Marc le llevó unas pocas - iteraciones el obtener algo con lo que estaban contentos. -
- -- Mientras Marc trabajaba en eso, Andy portó XLS a Java, basándose - en la biblioteca de Marc. Varios usuarios escribieron peticiones - para poder leer XLS (no sólo escribirlo como había sido planeado - originalmente) y un usuario tenía peticiones especiales para - un uso diferente de POIFS. Antes de que pasara mucho tiempo, - el alcance del proyecto se había triplicado. POI 1.0 se distribuyó - un mes más tarde de lo planeado, pero con muchas más características. - Marc escribió rápidamente el marco del serializador y el - Serializador HSSF en tiempo récord y Andy generó más documentación - y trabajó en hacer que la gente conociera este proyecto. -
- -- Poco antes de la distribución, POI tuvo la fortuna de entrar - en contacto con Nicola -Ken- Barrozzi quien proporcionó ejemplos - para el Serializador HSSF y ayudó a descrubir sus desafortunados - fallos (que fueron arreglados de inmediato). Recientemente, Ken - portó la mayoría de la documentación del proyecto POI a XML - partiendo de los documentos HTML cutres que Andy había escrito - con Star Office. -
- -- Más o menos al mismo tiempo de la primera distribución, Glen Stampoultzis - se unió al proyecto. A Glen le molestaba la actitud impertinente de Andy - en lo que añadir capacidades gráficas a HSSF se refería. Glen se molestó - tanto que decidió coger un martillo y hacerlo él mismo. Glen ya se ha - convertido en parte integral de la comunidad de desarrollo de POI; sus - contribuciones a HSSF ya han comenzado a producir olas. -
- -- En algún momento decidimos finalmente remitir el proyecto a - El Proyecto Cocoon - de Apache, sólo para descubrir que el proyecto había - crecido encajando perfectamente con Cocoon hacía tiempo. - Lo que es más, Andy comenzó a ojear otros proyectos a los que - le gustaría que se añadiera la funcionalidad de POI. Así que - se decidió donar los Serializadores y Generadores a Cocoon, otros - componentes de integración con POI a otros proyectos, y los APIs - de POI pasarían a formar parte de Jakarta. Fue un camino con - baches, ¡pero parece que todo salió bien puesto que ahora estás - leyendo esto! -
- -- Primero abordaremos esto desde el punto de vista del proyecto: - Bueno, les hicimos la oferta a Microsoft y Actuate (de coña - ... en su mayor parte) de que dejaríamos el proyecto y nos - retiraríamos si simplemente nos firmaban a cada uno un cheque - con muchos ceros. Todavía estoy esperando una llamada o correo - electrónico, así que de momento asumo que no nos van a pagar - para quitarnos de en medio. -
-- Después, tenemos algo de trabajo que hacer aquí en Jakarta - para terminar de integrar POI en la comunidad. Lo que es más, - todavía estamos realizando la transición del Serializador a - Cocoon. -
-- HSSF, durante el ciclo 2.0, sufrirá varias optimizaciones. - También añadiremos nuevas características como una implementación - completa de Fórmulas y formatos de texto personalizados. Esperamos - ser capaces de generar ficheros más pequeños añadiendo soporte de - escritura para registros RK, MulRK y MulBlank. A día de hoy, la - lectura en HSSF no es muy eficiente. Esto se debe sobre todo a que - para escribir o modificar, uno necesita ser capaz de actualizar - punteros del flujo de subida (upstream pointers) a datos del flujo - de bajada. Para hacer esto hay que tener todo lo que haya en - medio en memoria. En vez de eso, un Generador permitiría que se - procesaran eventos SAX. (Esto se basará en las estructuras de - bajo nivel). Una de las mejores cosas sobre esto es que así no sólo - tendremos una manera más eficiente de leer el fichero, también - tendremos una magnífica forma de utilizar hojas de cálculo como - fuentes de datos XML. -
-- El Serializador HSSF, se separará más aún en un marco genérico - para la creación de serializadores para otras plataformas y - en la implementación específica del serializador HSSF. (Esto ya - es cierto en gran medida). También añadiremos soporte para - características ya soportadas por HSSF (estilos, fuentes, formatos - de texto). Esperamos añadir soporte para fórmulas durante este ciclo. -
-- Estamos empezando a expandir nuestro alcance de nuevo. Si pudimos - hacer todo esto para ficheros XLS, ¿qué hay de ficheros Doc o PPT? - Pensamos que nuestro siguiente componente (HDF - Formato de - Documento Horrible) debería seguir el mismo patrón. Esperamos - que se nos una sangre nueva al equipo y que nos permita abordar - esto con mayor celeridad (en parte porque POIFS ya está terminado). - ¡Pero a lo mejor lo que más necesitamos es a ti! -
-- Puede ser que no es buen idea hablar de nuestra competidores pero nosotros creemos que la compentencia es bueno y que tenemos disponible hoy en día la mejor solución para escribir y leer archivos de Excel -
-| Producto | -URL | -Descripción | -
| Formula One | -- www.tidestone.com - | -- Una alternativa a este proyecto es comprar a $10,000 (dolares EEUU) el "Formula 1 library" y aceptar su API immadura y sus limitaciones. - | -
| Visual Basic | -- www.microsoft.com - | -- Deja de usar XML y escriba su programa usando Visual Basic en una computadora de Microsoft Windows. O trata de crear una solución usando la versión beta e indocumentada del nuevo formato de Microsoft llamado 'XML for Office'. - | -
| JExcel | -http://stareyes.homeip.net:8888 | -Frequentemente no está disponible. Se conoce poco acerca de - las habilidades de este programa. - | -
| JWorkbook | -http://www.object-refinery.com/jworkbook/index.html | -- Este esfuerzo puede trabajar con Gnumeric y Excel, pero la parte de Excel lo hace usando POI de todas formas. - | -
| xlReader | -http://www.sourceforge.net/projects/xlrd | -Funciona bastante bien leyendo Excel. - | -
| Excel ODBC Driver | -http://www.nwlink.com/~leewal/content/exceljavasample.htm | -ODBC ofrece una forma bastante rara para trabajar con Excel. - | -
| ExtenXLS | -http://www.extentech.com/products/ExtenXLS/docs/intro3.jsp | -Una biblioteca commercial para leer, modificar, y escribir hojas de balance de Excel. No es barato pero cuesta menos que Formula 1. No tenemos idea de la calidad de este software. - | -
| J-Integra Java-Excel Bridge | -http://www.intrinsyc.com/products/bridging/jintegra.asp | -Usa DCOM a una instancia de Excel en una computadora de Windows. - | -
| Perl & C | -- | -Hay varias bibliotecas en los idiomas de Perl y C. Pero no son consistentes o compatibles. - | -
| VistaJDBC | -http://www.vistaportal.com/products/vistajdbc.htm | -El driver de VistaJDBC trabaja con hojas de balance de StarOffice y Excel y proveen acceso al data sin tener que programar usando SQL estandar. VistaJDBC tambien permite escoger cellulas no solo por columna y fila per tambien cellulas individuales específicas, juegos de celulas, etc. - | -
| Coldtags Excel Tag Library | -http://www.servletsuite.com/servlets/exceltag.htm | -- Esta biblioteca ayuda a crear archivos en el formato de CSV, en la cual se permiten numeros y textos. Puede crear achivos de CSV sin esta ayuda, pero la bibioteca da estructura y leabilidad a su codigo y lo puede extender si necesita manejar casos mas complejos. Cuando un browser encuentra uno de estos páginas de JSP, abre una instancia de Excel automaticamente. No hay formatting, hojas de balance distintas, etc. O sea que, estrictamente, no es un competidor pero en algunos casos es todo lo que se necesita. - | -
- - Se espera usar esta sección para diagramas (UML/etc) que ayudan a - explicar HSSF. -
-- Tiene más? Agrega un nuevo "bug" al archivo de bugs con la - palabra [DOCUMENTATION] antes de la descripción y un link al file en algun webserver. Si no tiene su propio webserver, mandaselo por email a (acoliver at apache dot org) siempre y cuando el tamaño del archivo es menor a 5 Mb. Diagramas deben estar en algun formato compatible, por lo menos, con Linux y Windows. Se prefieren diagramas que se pueden cambiar o modificar pero entendemos que hay pocos programas para crear UML que están a buen precio. Y no, no TIENEN que ser UML... solo tienen que ser utiles. -
-- This document describes the current state of formula support in POI. - The information in this document applies to the 2.0-dev version of POI (i.e. CVS HEAD). - Since this area is a work in progress, this document will be updated with new features as and - when they are added. -
- -- In org.apache.poi.hssf.usermodel.HSSFCell - setCellFormula("formulaString") is used to add a formula to sheet and - getCellFormula() is used to retrieve the string representation of a formula. -
-- We aim to support the complete excel grammer for formulas. Thus, the string that you pass in - to the setCellFormula call should be what you expect to type into excel. Also, note - that you should NOT add a "=" to the front of the string. -
-- Formulas in Excel are stored as sequences of tokens in Reverse Polish Notation order. The - open office XLS spec is the best - documentation you will find for the format. -
- -- The tokens used by excel are modelled as individual *Ptg classes in the - org.apache.poi.hssf.record.formula package. -
-- The task of parsing a formula string into an array of RPN ordered tokens is done by the - org.apache.poi.hssf.record.formula.FormulaParser class. This class implements a hand - written recursive descent parser. -
-Check out the javadocs for details. -
-- You might find the - 'Excel 97 Developer's Kit' (out of print, Microsoft Press, no - restrictive covenants, available on Amazon.com) helpful for - understanding the file format. -
-- Also useful is the open office XLS spec. We - are collaborating with the maintainer of the spec so if you think you can add something to their - document just send through your changes. -
-- Low level records can be time consuming to created. We created a record - generator to help generate some of the simpler tasks. -
-- We use XML - descriptors to generate the Java code (which sure beats the heck out of - the PERL scripts originally used ;-) for low level records. The - generator is kinda alpha-ish right now and could use some enhancement, - so you may find that to be about 1/2 of the work. Notice this is in - org.apache.poi.hssf.record.definitions. -
-One thing to note: If you are making a large code contribution we need to ensure - any participants in this process have never - signed a "Non Disclosure Agreement" with Microsoft, and have not - received any information covered by such an agreement. If they have - they'll not be able to participate in the POI project. For large contributions we - may ask you to sign an agreement.
-Check our todo list or simply look for missing functionality. Start small - and work your way up.
-Make sure you read the contributing section - as it contains more generation information about contributing to Poi in general.
-This release of the how-to outlines functionality for the CVS HEAD. - Those looking for information on previous releases should - look in the documentation distributed with that release.
-- This release allows numeric and string cell values to be written to - or read from an XLS file as well as reading and writing dates. Also - in this release is row and column sizing, cell styling (bold, - italics, borders,etc), and support for built-in data formats. New - to this release is an event-based API for reading XLS files. - It differs greatly from the read/write API - and is intended for intermediate developers who need a smaller - memory footprint. It will also serve as the basis for the HSSF - Generator.
-The high level API (package: org.apache.poi.hssf.usermodel) - is what most people should use. Usage is very simple. -
-Workbooks are created by creating an instance of - org.apache.poi.hssf.usermodel.HSSFWorkbook. -
-Sheets are created by calling createSheet() from an existing - instance of HSSFWorkbook, the created sheet is automatically added in - sequence to the workbook. Sheets do not in themselves have a sheet - name (the tab at the bottom); you set - the name associated with a sheet by calling - HSSFWorkbook.setSheetName(sheetindex,"SheetName",encoding). - The name may be in 8bit format (HSSFWorkbook.ENCODING_COMPRESSED_UNICODE) - or Unicode (HSSFWorkbook.ENCODING_UTF_16). Default encoding is 8bit per char. -
-Rows are created by calling createRow(rowNumber) from an existing - instance of HSSFSheet. Only rows that have cell values should be - added to the sheet. To set the row's height, you just call - setRowHeight(height) on the row object. The height must be given in - twips, or 1/20th of a point. If you prefer, there is also a - setRowHeightInPoints method. -
-Cells are created by calling createCell(column, type) from an - existing HSSFRow. Only cells that have values should be added to the - row. Cells should have their cell type set to either - HSSFCell.CELL_TYPE_NUMERIC or HSSFCell.CELL_TYPE_STRING depending on - whether they contain a numeric or textual value. Cells must also have - a value set. Set the value by calling setCellValue with either a - String or double as a parameter. Individual cells do not have a - width; you must call setColumnWidth(colindex, width) (use units of - 1/256th of a character) on the HSSFSheet object. (You can't do it on - an individual basis in the GUI either).
-Cells are styled with HSSFCellStyle objects which in turn contain - a reference to an HSSFFont object. These are created via the - HSSFWorkbook object by calling createCellStyle() and createFont(). - Once you create the object you must set its parameters (colors, - borders, etc). To set a font for an HSSFCellStyle call - setFont(fontobj). -
-Once you have generated your workbook, you can write it out by - calling write(outputStream) from your instance of Workbook, passing - it an OutputStream (for instance, a FileOutputStream or - ServletOutputStream). You must close the OutputStream yourself. HSSF - does not close it for you. -
-Here is some example code (excerpted and adapted from - org.apache.poi.hssf.dev.HSSF test class):
-Reading in a file is equally simple. To read in a file, create a -new instance of org.apache.poi.poifs.Filesystem, passing in an open InputStream, such as a FileInputStream -for your XLS, to the constructor. Construct a new instance of -org.apache.poi.hssf.usermodel.HSSFWorkbook passing the -Filesystem instance to the constructor. From there you have access to -all of the high level model objects through their assessor methods -(workbook.getSheet(sheetNum), sheet.getRow(rownum), etc). -
-Modifying the file you have read in is simple. You retrieve the -object via an assessor method, remove it via a parent object's remove -method (sheet.removeRow(hssfrow)) and create objects just as you -would if creating a new xls. When you are done modifying cells just -call workbook.write(outputstream) just as you did above.
-An example of this can be seen in -org.apache.poi.hssf.dev.HSSF.
-The event API is brand new. It is intended for intermediate - developers who are willing to learn a little bit of the low level API - structures. Its relatively simple to use, but requires a basic - understanding of the parts of an Excel file (or willingness to - learn). The advantage provided is that you can read an XLS with a - relatively small memory footprint. -
-To use this API you construct an instance of - org.apache.poi.hssf.eventmodel.HSSFRequest. Register a class you - create that supports the - org.apache.poi.hssf.eventmodel.HSSFListener interface using the - HSSFRequest.addListener(yourlistener, recordsid). The recordsid - should be a static reference number (such as BOFRecord.sid) contained - in the classes in org.apache.poi.hssf.record. The trick is you - have to know what these records are. Alternatively you can call - HSSFRequest.addListenerForAllRecords(mylistener). In order to learn - about these records you can either read all of the javadoc in the - org.apache.poi.hssf.record package or you can just hack up a - copy of org.apache.poi.hssf.dev.EFHSSF and adapt it to your - needs. TODO: better documentation on records.
-Once you've registered your listeners in the HSSFRequest object - you can construct an instance of - org.apache.poi.poifs.filesystem.FileSystem (see POIFS howto) and - pass it your XLS file inputstream. You can either pass this, along - with the request you constructed, to an instance of HSSFEventFactory - via the HSSFEventFactory.processWorkbookEvents(request, Filesystem) - method, or you can get an instance of DocumentInputStream from - Filesystem.createDocumentInputStream("Workbook") and pass - it to HSSFEventFactory.processEvents(request, inputStream). Once you - make this call, the listeners that you constructed receive calls to - their processRecord(Record) methods with each Record they are - registered to listen for until the file has been completely read. -
-A code excerpt from org.apache.poi.hssf.dev.EFHSSF (which is - in CVS or the source distribution) is reprinted below with excessive - comments:
-The low level API is not much to look at. It consists of lots of -"Records" in the org.apache.poi.hssf.record.* package, -and set of helper classes in org.apache.poi.hssf.model.*. The -record classes are consistent with the low level binary structures -inside a BIFF8 file (which is embedded in a POIFS file system). You -probably need the book: "Microsoft Excel 97 Developer's Kit" -from Microsoft Press in order to understand how these fit together -(out of print but easily obtainable from Amazon's used books). In -order to gain a good understanding of how to use the low level APIs -should view the source in org.apache.poi.hssf.usermodel.* and -the classes in org.apache.poi.hssf.model.*. You should read the -documentation for the POIFS libraries as well.
-The HSSF application is nothing more than a test for the high -level API (and indirectly the low level support). The main body of -its code is repeated above. To run it: -
-export HSSFDIR={wherever you put HSSF's jar files}
-export LOG4JDIR={wherever you put LOG4J's jar files}
-export CLASSPATH=$CLASSPATH:$HSSFDIR/hssf.jar:$HSSFDIR/poi-poifs.jar:$HSSFDIR/poi-util.jar:$LOG4JDIR/jog4j.jar
- java org.apache.poi.hssf.dev.HSSF ~/myxls.xls writeThis should generate a test sheet in your home directory called "myxls.xls".
java org.apache.poi.hssf.dev.HSSF ~/input.xls output.xls
- Poi can dynamically select it's logging implementation. Poi trys to - create a logger using the System property named "org.apache.poi.util.POILogger". - Out of the box this can be set to one of three values: -
-- If the property is not defined or points to an invalid classthen the NullLogger is used. -
-- Refer to the commons logging package level javadoc for more information concerning how to - configure commons logging. -
-HSSF has a number of tools useful for developers to debug/develop -stuff using HSSF (and more generally XLS files). We've already -discussed the app for testing HSSF read/write/modify capabilities; -now we'll talk a bit about BiffViewer. Early on in the development of -HSSF, it was decided that knowing what was in a record, what was -wrong with it, etc. was virtually impossible with the available -tools. So we developed BiffViewer. You can find it at -org.apache.poi.hssf.dev.BiffViewer. It performs two basic -functions and a derivative. -
-The first is "biffview". To do this you run it (assumes -you have everything setup in your classpath and that you know what -you're doing enough to be thinking about this) with an xls file as a -parameter. It will give you a listing of all understood records with -their data and a list of not-yet-understood records with no data -(because it doesn't know how to interpret them). This listing is -useful for several things. First, you can look at the values and SEE -what is wrong in quasi-English. Second, you can send the output to a -file and compare it. -
-The second function is "big freakin dump", just pass a -file and a second argument matching "bfd" exactly. This -will just make a big hexdump of the file. -
-Lastly, there is "mixed" mode which does the same as -regular biffview, only it includes hex dumps of certain records -intertwined. To use that just pass a file with a second argument -matching "on" exactly.
-In the next release cycle we'll also have something called a -FormulaViewer. The class is already there, but its not very useful -yet. When it does something, we'll document it.
- -This release contains code that supports "internationalization" -or more accurately non-US/UK languages; however, it has not been -tested with the new API changes (please help us with this). We've -shifted focus a bit for this release in recognition of the -international support we've gotten. We're going to focus on western -European languages for our first beta. We're more than happy to -accept help in supporting non-Western European languages if someone -who knows what they're doing in this area is willing to pitch in! -(There is next to no documentation on what is necessary to support -such a move and its really hard to support a language when you don't even -know the alphabet).
-This release of HSSF does not yet support Formulas. I've been -focusing on the requests I've gotten in. That being said, if we get -more user feedback on what is most useful first we'll aim for that. -As a general principal, HSSF's goal is to support HSSF-Serializer -(meaning an emphasis on write). We would like to hear from you! How -are you using HSSF/POIFS? How would you like to use it? What features -are most important first? -
-HSSF is the POI Project's pure Java implementation of the Excel '97(-2002) file format.
-HSSF provides a way to read spreadsheets create, modify, read and write XLS spreadsheets - It provides: -
-- Truth be told there is probably a better way to generate your spreadsheet - generation (yet you'll still be using HSSF indirectly). At the time of - this writing we're in the process of moving the HSSF Serializer over to - the Apache Cocoon - Project. With Cocoon you can serialize any XML datasource (of - which might be a ESQL page outputting in SQL for instance) by simply - applying the stylesheet and designating the serializer. -
-- If you're merely reading spreadsheet data, then use the eventmodel api - in the org.apache.poi.hssf.eventmodel package. -
-- If you're modifying spreadsheet data then use the usermodel api. You - can also generate spreadsheets this way, but using Cocoon (which will do - it this way indirectly) is the best way...we promise. -
- -- The intent of this document is to outline some of the known limitations of the - POI HSSF API's. It is not intended to be complete list of every bug or missing - feature of HSSF, rather it's purpose is to provide a broad feel for some of the - functionality that is missing or broken. -
-- Want to use HSSF read and write spreadsheets in a hurry? This guide is for you. If you're after - more in-depth coverage of the HSSF user-API please consult the HOWTO - guide as it contains actual descriptions of how to use this stuff. -
-- The record generator was born from frustration with translating - the Excel records to Java classes. Doing this manually is a time - consuming process. It's also very easy to make mistakes. -
-- A utility was needed to take the defintition of what a - record looked like and do all the boring stuff. Thus the - record generator was born. -
-- The record generator takes XML as input and produced the following - output: -
- The record generator is invoked as an Ant target (generate-records). It goes - through looking for all files in src/records/defintitions ending with _record.xml. - It then creates two files; the Java record definition and the Java test case template. -
-- The records themselves have the following general layout: -
-- Currently the type can be of type int, float or string. The 'int' - type covers bytes, shorts and integers which is selected using a - size of 1, 2 or 4. An additional type called varword is used to - represent a array of word values where the first short is the length - of the array. The string type generation is only partially - implemented. If choosing string you must select a size of 'var'. -
-- The Java records are regenerated each time the record generator is - run, however the test stubs are only created if the test stub does - not already exist. What this means is that you may change test - stubs but not the generated records. -
-- The record generation works by taking an XML file and styling it - using XLST. Given that XSLT is a little limited in some ways it was - necessary to add a little Java code to the mix. -
-- See record.xsl, record_test.xsl, FieldIterator.java, - RecordUtil.java, RecordGenerator.java -
-- The record generator does not handle all possible record types and - is not ment to. Sometimes it's going to make more sense to generate - the records manually. The main point of this thing is to make the - easy stuff simple. -
-- Currently the record generator is optimized to create Excel records. - It could be adapted to create Word records with a little poking - around. -
-- Currently the the XSL file that generates the record calls out to - Java objects. This would have been better done as Javascript inside - the XSL file itself. The Java code for the record generation is - currently quite messy with minimal comments. -
-Primary Actor: HSSF client
-Scope: HSSF
-Level: Summary
-Stakeholders and Interests:
-Precondition: None
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions:
-2a. Exceptions -thrown by POIFS will be passed on to the HSSF client.
-Primary Actor: HSSF client
-Scope: HSSF
-Level: Summary
-Stakeholders and Interests:
-Precondition:
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions:
-3a. Exceptions -from POIFS are passed to the HSSF client.
- -Primary Actor: HSSF client
-Scope: HSSF
--Level: Summary
-Stakeholders and Interests:
-Precondition:
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions: -None
- -Primary Actor: HSSF
-Scope: HSSF
--Level: Summary
-Stakeholders and Interests:
-Precondition:
-Minimal -Guarantee: None
-Main Success Guarantee:
-Extensions:
-3a. Exceptions -thrown by POIFS will be passed on
-Primary Actor: HSSF
-Scope: HSSF
--Level: Summary
-Stakeholders and Interests:
-Precondition: -
-Minimal Guarantee: None
-Main Success Guarantee:
-Extensions:None
-- El proyecto de traducción de la documentación de POI ha comenzado. - Los primeros en empezar han sido las traducciones al Español - , al Japonés y al - Alemán. - Otras serán bienvenidas. ¡Podéis participar si queréis! -
-- Se ha terminado el plazo de votaciones para el concurso de logotipo de POI. Gracias por vuestros votos. -
- - - -- El proyecto POI consiste en APIs para manipular varios formatos de ficheros, - basados en el formato de Documento Compuesto OLE 2 de Microsoft, utilizando Java puro. -
-- Entre los ficheros basados en el formato de Documento Compuesto OLE 2 de Microsoft se - incluyen la mayor parte de los ficheros de Microsoft Office tales como XLS y DOC. -
-- Como regla general intentamos colaborar lo más posible con otros proyectos para proporcionar esta - funcionalidad. Algunos ejemplos: Cocoon para - el que pronto encontraréis generadores y serializadores para nuestros proyectos; - Open Office.org con quienes colaboramos en la - documentación del formato XLS; y Lucene para - el que pronto tendremos intérpretes del formato de fichero. Cuando sea práctico, donaremos componentes - directamente a aquellos proyectos para dotarles de capacidad-POI. -
-- Abordaremos esto a nivel de componente. POI se refiere al proyecto completo. -
-- Así que, ¿por qué debería utilizar POIFS o HSSF? -
-- Utilizarías POIFS si tuvieras un documento escrito en el Formato de Documento Compuesto OLE 2, probablemente - escrito utilizando MFC, que necesitaras leer en Java. Alternativamente, utilizarías POI para escribir - en el Formato de Documento Compuesto OLE 2 si necesitaras inter-operar con programas ejecutándose en la - plataforma Windows. No nos estamos jactando cuando decimos que POIFS es la adaptación más completa y correcta - de este formato de fichero hasta la fecha. -
-- Utilizaríás HSSF si necesitaras leer o escribir un fichero XLS (Excel) utilizando Java. También se pueden - leer y modificar hojas de cálculo utilizando este API, aunque ahora mismo la escritura está más madura. -
-- POI significa Implementación Pobre de Ofuscación (Poor Obfuscation Implementation). ¿Por qué daríamos a - nuestro proyecto un nombre tan derogatorio? Bien, el Formato de Documento Compuesto OLE 2 de Microsoft es - algo bastante mal concebido. Esencialmente es un fichero estructurado muy a la manera del viejo sistema FAT - del DOS. Redmon eligió, en vez de utilizar tar, gzip, o arc, inventar su propio formato de fichero que no - proporciona ningún estándar de cifrado o compresión, no es fácil de unir con otros ficheros del mismo tipo, y - es dado a sufrir problemas de fragmentación. -
-- Poi también es una delicatessen Hawaiiana que el diccionario Merriam Webster's - define como "Comida Hawaiiana de raiz de taro cocinada, machacada y amasada en una pasta que a menudo se deja fermentar." - Esto extrañamente parecía una descripción del formato del fichero. -
-- Así que si te gustan los acrónimos, entonces POI es un acrónimo. Si los odias, entonces sólo usamos el nombre de la - comida para nuestro proyecto. Si deseas expresar amor u odio por los acrónimos, utiliza POI o Poi respectivamente - para referirte al proyecto. -
-Un concepto erróneo es que POI escribe ficheros Excel. POI es el nombre del proyecto. POI contiene varios - componentes, uno de los cuales, HSSF, escribe ficheros Excel. Siguen a continuación los componentes del - proyecto POI completo y un pequeño sumario de su propósito.
-POIFS es la parte más vieja y más estable del proyecto. Es nuestra adaptación del Formato de Documento Compuesto - OLE 2 a Java puro. Soporta funcionalidad de lectura y escritura. Todos nuestros componentes se sirven de él por - definición. Por favor, vea la página del proyecto POIFS para más información.
-HSSF es nuestra adaptación del formato de fichero de Microsoft Excel 97(-2002) a Java puro. Soporta lectura y - escritura. Por favor, vea la página del proyecto HSSF para más información.
-HDF es nuestra adaptación del formato de fichero de Microsoft Word 97 a Java puro. Soporta lectura y escritura. - Por favor, vea la página del proyecto HDF para más información. Este - componente está en la fase inicial de diseño. ¡Salta dentro!
-HPSF es nuestra adaptación del formato de conjunto de propiedades OLE 2 a java puro. - Los conjuntos de propiedades se utilizan mayoritariamente para almacenar las propiedades de un documento - (título, autor, fecha de la última modificació, etc.), pero también pueden ser utilizados para propósitos - específicos de una aplicación. Actualmente HPSF soporta sólo funcionalidad de lectura. Por favor, vea - la página del proyecto HPSF para más información.
-El Serializador HSSF, que era parte de nuestra release 1.0 y de las últimas compilaciones en - Sourceforge, ha sido donado al proyecto - Cocoon, y está disponible a partir de la versión - 2.0.2.
-- ¿Así que te gustaría contribuir al proyecto? ¡Genial! Necesitamos gente entusiasta, que trabaje duro, - que tenga talento para ayudarnos con el proyecto en varias áreas. ¡La primera es petición de nuevas - funciones y aviso de errores! La segunda es documentación - estaremos a tu entera disposición si - tienes alguna crítica o te gustaría contribuir o mejorar de alguna forma la documentación. ¡Especialmente - no nos vendría mal algo de ayuda en documentar el formato de fichero HSSF! ¡Por último, aunque no por ello - menos importante, nos vendría bien algunos programadores Java que mastiquen binario, para que le echen el diente - a la convolución que caracteriza los formatos de fichero de Microsoft y para que nos ayude a adaptar nuevos - formatos a una plataforma Java superior! -
-¡Así que si estás motivado, listo, y tienes tiempo, únete a las listas de correo y estaremos encantados de ayudarte a - empezar en el proyecto! -
- - -- Estos son artículos/etc. sobre POI publicados en la red. Si ves - alguna noticia sobre POI o algún sitio en el que se le menciona - de manera notable (no en tu propia página en la que pones la palabra - POI para que enlacemos contigo y en la que casualmente hay una foto - de tu mujer e hijos) entonces envía un parche a la lista. En general - dedicaremos el mismo tiempo así que no tengáis reparos en enviar - difamaciones coléricas así como comentarios favorables, técnicos y - objetivos. No mencionaremos mensajes realmente estúpidos (lo sentimos). -
-- ¡Si entiendes alguno de estos idiomas, envía un correo a la lista - diciéndonos en qué idioma está escrito y lo pondremos donde corresponda! -
-El proyecto POI es el proyecto principal para el desarrollo de adaptaciones (ports) - en Java puro de los formatos de fichero basados en el Formato de Documento Compuesto OLE 2 - de Microsoft. El Formato de Documento Compuesto OLE 2 lo utilizan los Documentos Office de - Microsoft, así como por los programas que utilizan conjuntos de propiedades MFC para serializar - sus objetos de tipo documento. -
-- Los siguientes son adaptaciones, paquetes o componentes contenidos en el proyecto POI. -
-- POIFS es el conjunto de APIs - (Interfaces de Aplicación) para la lectura y escritura del Formato de Documento Compuesto OLE 2 - utilizando (únicamente) Java. -
-- HSSF es el conjunto de APIs para la lectura y - escritura de hojas de cálculo de Microsoft Excel 97(-XP) utilizando (únicamente) Java. -
-- HDF es el conjunto de APIs para la lectura y - escritura de documentos Word 97(-XP) de Microsoft utilizando (únicamente) Java. -
-- HPSF es el conjunto de APIs para la lectura - de conjuntos de propiedades utilizando (únicamente) Java. -
-- POI-Utils son artefactos de propósito - general surgidos en el desarrollo de POI que no han sido implementados en ningún otro sitio. - Siempre buscamos donarlos y mantenerlos como parte de una biblioteca general utilizada en - algún otro proyecto. Estas son cosas que necesitamos para completar nuestra misión pero que - generalmente estan fuera de ella. -
-
- This is an informal list - in chronological order -
- of some of the noteworthy patches that have been posted
- to the developers mailing list.
- These patches are not (yet) part of the Poi project, but need reviewing for possible
- inclusion. This system was instituted because, due to the large volume of mail and
- the lack of time of the committers, some patches tended to get forgotten about. This
- queue does not guarantee that any patch will be reviewed within a reasonable time frame,
- but it does at least make them easier to find!
-
Reviewers wanted! - If you have time to review and/or test these patches, - we would be grateful for your time. Please post comments to the dev mailing lists. -
- Before submitting a patch, please read the page on
diff -u format from CVSFollowing the above guidelines will facilitate your patch being reviewed - and applied efficiently.
[Under Construction] Archive links will be added later.
- Please do not bother the patch submitters/authors without first reading the
- relevant post(s) in the
Vapourware will not be listed.
| id | Summary | Reviewer | Resolution | Status |
|---|
See also additional list of patches to be added in
- The Poi Project operates on a meritocracy: the more you do, the more - responsibility you will obtain. This page lists all of the people who have - gone the extra mile and are Committers. If you would like to get involved, - the first step is to join the mailing lists. -
- -- We ask that you please do not send us emails privately asking for support. - We are non-paid volunteers who help out with the project and we do not - necessarily have the time or energy to help people on an individual basis. - Instead, we have set up mailing lists which often contain hundreds of - individuals who will help answer detailed requests for help. The benefit of - using mailing lists over private communication is that it is a shared - resource where others can also learn from common mistakes and as a - community we all grow together. -
- -This document hopes to serve as a general introduction and helpful set of - guidelines for translating POI documentation into other languages. We hope - to capture both general information here (such as "how do I test my changes") - as well as language specific guidelines and translation conventions.
-- POI's XML based documentation is built along side the sources. To build poi's documentation - you run "./build.sh docs" (UNIX/cygwin) or "build docs" (Windows) from the jakarta-poi - directory. This will put the documentation under the build/docs directory, you can navigate - there using your browser generally by typing in the path name or File -> Open new web location - (or some similar wording) - and browsing to the "index.html" file. You may also want to run "./build.sh clean docs" or - "build clean docs" so that all documentation previously built is erased before running the build. - The words "clean" and "docs" are called "targets", from here on out we will refer to them as - "targets" in which case you may assume you type "./build.sh" or "build" before them in order to - execute them. -
-- To generate all of teh documentation such as it would appear on the - POI Website you can execute the "site" target (optionally - preceeded by the "clean" target. -
-- The source for POI's XML documentation is in src/documentation/xdocs. To edit one of these files you can use - a standard text editor. Translated documentation is under src/documentation/xdocs/trans/xx, where xx is a - two to three letter country code, in general this should match the internet domain suffix of the country where - that language generally evolved or just be generally recognizable and unique. The directory structure under - src/documentation/trans/xx should match the structure of src/documentation (the English edition) minus the - trans directory. -
-- The translated documentation should match the content and meaning of the "master" or English documentation. - All documentation should originate in English (this is for simplicity). While documentation written in other - languages is certainly welcome, it must first be translated (perhaps by posting it to the mail list and - requesting it be translated) into English and applied to the master before being applied to a translation. -
-- We prefer you donate translations directly to the Jakarta POI - project rather than hosting them offsite. We will make every effort to accomidate you as we greatly appreciate your - efforts. However, we understand that sites located within a country are the fastest and most searchable. Therefore, - we recommend and welcome folks mirroring the POI site and making the translated page the home page. You can do this - either via an HTML copy with some appropriate software - or the preferred method of executing the POI build directly. You can contact us via the mail list for both push and - pull options. The same scripts which regenerate the POI website every 2 hours, should work for others. These are not - yet in CVS as they are nasty dirty shell scripts ;-). If you mirror us, tell us so we can link you. (This will help google - associate you strongly with the project) -
-- Submitting translations is simple, you follow the same - instructions as you would for submitting a code patch. - Remeber to always generate patchs in diff -u format preserving the context relative to the jakarta-poi directory. Also remember - to submit any new files in a directory preserving archive format. Never post these to the list, always use - Bugzilla - and create attachments per the above linked instructions. -
-- Some people feel uncomfortable putting themselves in the <authors> tags at the top of the documentation as they feel that - translation does not give them the right to claim authorship. Please don't feel this way, please add yourself to the authors - tags. It can be assumed that authors on the master documentation are all content creators and any additional authors listed - on the translation that are not on the master document are translators of the documentation. You authored the xx language - version of the document and should freely add yourself there. Additionally, please supply a patch to the - Who We Are page noting you as a developer once you've submitted a few translation patches. You deserve - credit and it helps the project to give you credit. Remember documentation is on par with code contribution. -
-- To start a translation for a language not already in existance you must create a directory under src/documentation/xdocs/trans with a - two or three letter designation of the country where the language originated. (For example es = Spanish, de = German) - Copy the book.xml and index.xml file from src/documentation/xdocs directory into the src/documentation/xdocs/trans/xx directory. - Change all paths in the book.xml and index.xml to match the relative location of the English version. For example if there is a - link in index.html that references ./poifs/index.html, you'd change that to ../../poifs/index.html (up 2 directories from trans/xx). - Create a link from the book.xml file in the src/documentation/trans directory (this is necessary or the build will ignore your - documentation) similar to the other languages. - Run the clean target followed by the docs target. If the build is successful, congradulations! If it fails, you probably got one of - the relative paths incorrect! Go fix it (the first error message generally contains the most useful information). If you need help - post to the poi-dev list and ask for it (send the output from the build). -
-- So now you have a directory with a copy of the index from the master documentation...so what? Well now translate book.xml and index.xml. - Try to build again. It probably won't work. Why? The encoding. At the top of every file there is an encoding="UTF-8" (in general). - This encoding will work for many Western European languages, but not for others, or will require some nasty escape sequencing. This is - where trial and error + guess work come in. This Table of encodings may help. There is a - catch. Your encoding should work on a Linux system under Java 1.3.1 and of course with the build in general. If in doubt, ask. - (This is a practical consideration as thats the setup of the machine currently running the nightly/site builds.) -
-- Andy Oliver is the cofounder of the POI project and one of its most active documentation contributers. Well, Andy used to think he - spoke very clearly until he traveled abroad and discovered his speech was composed almost entirely of coloquialisms. This can make some - of the POI documentation difficult to translate, if in doubt...ask. Its also appropriate to eliminate these from the master documentation - where it makes it clearer. -
-- In addition to the above practical guidelines we hope to come up with a set of translation guidelines here (or linked from here) for - general use as well as language specific translation guidelines and conventions. We assume that the POI translators will document - them here as they develop. -
-- The POI project has always had a very international following. In fact even today POI is - more popular in Europe than in the US where the original founders reside. Today POI is - developed by people from all over the world including India, Austrailia, Japan, and Russia. - We recognize and welcome our geographically and culturally diverse users and contributors and - wish to accomidate you as best as we can. -
-- Documentation has always been a cornerstone to POI's success. No matter how fluent one is in - a second language, it is always easier to comprehend concepts explained in one's native language, - therefore, we encourage volunteers to come and help us translate the documentation into other - languages. Below is a list of the translations that are currently in progress and their status. -
-| xx | Language | Status | On/Offsite | Link |
| de | German | Just beginning (help!) | On | -link |
| es | Spanish | Index page, some auxiliary pages translated | On | -link |
| jp | Japanese | Complete XML translation, a few releases old | Off | -link |
The POI Utils are classes we're looking to donate elsewhere and include. - These are usually classes that while are required for our mission, - are somehow outside of it. General utilities that could be used in - any project are what we would normally put here. If you see one, and you - think "gee that would be great as part of X project" then let us know. - While we wish to put these in their rightful place, we also don't want to - include a 40mb jar file just to process text strings, so that will - be a consideraton. -
-- Currently, we're looking into which subprojects in the Jakarta Commons project - to donate these too. The "Poi Utils" package won't go away, as there may - be later classes. The idea is that "go ahead and add it, we'll merge it or - find an alternative later, just keep pounding out that poi!" -
- -- Logging in POI is used only as a debugging mechanism, not a normal runtime - logging system. Logging is ONLY for autopsie type debugging, and should - NEVER be enabled on a production system. Enabling logging will reduce - performance by at least a factor of 100. If you are not developing - POI or trying to debug why POI isn't reading a file correctly, then DO - NOT enable logging. You've been warned. -
- -- Hence, we need to be able to easily disable it entirely and make POI not dependent - on any logging package. -
- -
- Every class uses a POILogger to log, and gets it using a static method
- of the POILogFactory .
-
- The POILogFactory uses the NullLogger by default;
- it can be instructed to use any other POILogger implementation
- by setting the system property org.apache.poi.util.POILogger.
-
- Each class in POI can get its POILogger by calling a static method
- of the POILogFactory .
-
- Each class in POI can log using a POILogger, which is an abstract class.
- We decided to make our own logging facade because:
There are three implementations available, and you can roll out your own, just
- extend org.apache.poi.util.POILogger.
-
Discards every logging request.
-Sends every logging request to System.out.
-Sends every logging request to the Commons Logging package. This can use JDK1.4 logging, - log4j, logkit, and is an actively maintained Jakarta Project.
-- The Poi Project operates on a meritocracy: the more you do, the more - responsibility you will obtain. This page lists all of the people who have - gone the extra mile and are Committers. If you would like to get involved, - the first step is to join the mailing lists. -
- -- We ask that you please do not send us emails privately asking for support. - We are non-paid volunteers who help out with the project and we do not - necessarily have the time or energy to help people on an individual basis. - Instead, we have set up mailing lists which often contain hundreds of - individuals who will help answer detailed requests for help. The benefit of - using mailing lists over private communication is that it is a shared - resource where others can also learn from common mistakes and as a - community we all grow together. -
- -