96 lines
4.7 KiB
XML
96 lines
4.7 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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See the License for the specific language governing permissions and
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limitations under the License.
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====================================================================
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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.1//EN" "../dtd/document-v11.dtd">
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<document>
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<header>
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<title>Apache POI - POIFS - Documents embeded in other documents</title>
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<subtitle>Overview</subtitle>
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<authors>
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<person name="Nick Burch" email="nick@apache.org"/>
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<person name="Yegor Kozlov" email="yegor@apache.org"/>
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</authors>
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</header>
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<body>
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<section><title>Overview</title>
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<p>It is possible for one OLE 2 based document to have other
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OLE 2 documents embeded in it. For example, and Excel file
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may have a word document and a powerpoint slideshow
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embeded as part of it.</p>
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<p>Normally, these other documents are stored in subdirectories
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of the OLE 2 (POIFS) filesystem. The exact location of the
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embeded documents will vary depending on the type of the
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master document, and the exact directory names will differ
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each time. To figure out exactly which directory to look
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in, you will either need to process the appropriate OLE 2
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linking entry in the master document, or simple iterate
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over all the directories in the filesystem.</p>
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<p>As a general rule, you will find the same OLE 2 entries
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in the subdirectories, as you would've found at the root
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of the filesystem were a document to not be embeded.</p>
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<section><title>Files embeded in Excel</title>
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<p>Excel normally stores embeded files in subdirectories
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of the filesystem root. Typically these subdirectories
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are named starting with MBD, with 8 hex characters following.</p>
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</section>
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<section><title>Files embeded in Word</title>
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<p>Word normally stores embeded files in subdirectories
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of the ObjectPool directory, itself a subdirectory of the
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filesystem root. Typically these subdirectories and named
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starting with an underscore, followed by 10 numbers.</p>
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</section>
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<section><title>Files embeded in PowerPoint</title>
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<p>PowerPoint does not normally store embeded files
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in the OLE2 layer. Instead, they are held within records
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of the main PowerPoint file.
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<br/>See the <link href="./../slideshow/how-to-shapes.html#OLE">HSLF Tutorial</link>
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for how to retrieve embedded OLE objects from a presentation</p>
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</section>
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</section>
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<section><title>Listing POIFS contents</title>
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<p>POIFS provides a simple tool for listing the contents of
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OLE2 files. This can allow you to see what your POIFS file
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contents, and hence if it has any embeded documents in it,
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and where.</p>
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<p>The tool to use is <em>org.apache.poi.poifs.dev.POIFSLister</em>.
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This tool may be run from the command line, and takes a filename
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as its parameter. It will print out all the directories and
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files contained within the POIFS file.</p>
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</section>
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<section><title>Opening embeded files</title>
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<p>All of the POIDocument classes (HSSFWorkbook, HSLFSlideShow,
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HWPFDocument and HDGFDiagram) can either be opened from
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a POIFSFileSystem, or from a specific directory within a
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POIFSFileSystem. So, to open embeded files, simply locate the
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appropriate DirectoryNode that represents the subdirectory
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of interest, and pass this + the overall POIFSFileSystem to
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the constructor.</p>
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<p>I you want to extract the textual contents of the embeded file,
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then open the appropriate POIDocument, and then pass this to
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the extractor class, instead of simply passing the POIFSFilesystem
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to the extractor.</p>
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</section>
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</body>
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</document>
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