New FAQ
git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@352791 13f79535-47bb-0310-9956-ffa450edef68
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Glen Stampoultzis
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@ -7,9 +7,9 @@
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Why is reading a simple sheet taking so long?
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</question>
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<answer>
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You've probably enabled logging. Logging is intended only for
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You've probably enabled logging. Logging is intended only for
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autopsie style debugging. Having it enabled will reduce performance
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by a factor of at least 100. Logging is helpful for understanding
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by a factor of at least 100. Logging is helpful for understanding
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why POI can't read some file or developing POI itself. Important
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errors are thrown as exceptions, which means you probably don't need
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logging.
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@ -62,24 +62,25 @@
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<answer>
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Excel stores dates as numbers therefore the only way to determine if a cell is
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actually stored as a date is to look at the formatting. There is a helper method
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in HSSFDateUtil (since the 1.7.0-dev release) that checks for this.
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in HSSFDateUtil (since the 1.7.0-dev release) that checks for this.
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Thanks to Jason Hoffman for providing the solution.
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<source>
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case HSSFCell.CELL_TYPE_NUMERIC:
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double d = cell.getNumericCellValue();
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// test if a date!
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if (HSSFDateUtil.isCellDateFormatted(cell)) {
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// format in form of M/D/YY
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cal.setTime(HSSFDateUtil.getJavaDate(d));
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cellText =
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(String.valueOf(cal.get(Calendar.YEAR))).substring(2);
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cellText = cal.get(Calendar.MONTH)+1 + "/" +
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cal.get(Calendar.DAY_OF_MONTH) + "/" +
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cellText;
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}
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case HSSFCell.CELL_TYPE_NUMERIC:
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double d = cell.getNumericCellValue();
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// test if a date!
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if (HSSFDateUtil.isCellDateFormatted(cell)) {
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// format in form of M/D/YY
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cal.setTime(HSSFDateUtil.getJavaDate(d));
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cellText =
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(String.valueOf(cal.get(Calendar.YEAR))).substring(2);
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cellText = cal.get(Calendar.MONTH)+1 + "/" +
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cal.get(Calendar.DAY_OF_MONTH) + "/" +
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cellText;
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}
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</source>
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</source>
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</answer>
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</faq>
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<faq>
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@ -88,8 +89,8 @@
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</question>
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<answer>
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<p>
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The problem usually manifests itself as the junk characters being shown on
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screen. The problem persists even though you have set the correct mime type.
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The problem usually manifests itself as the junk characters being shown on
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screen. The problem persists even though you have set the correct mime type.
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</p>
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<p>
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The short answer is, dont depend on IE to display a binary file type you an attachment properly if you stream it via a
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@ -98,29 +99,35 @@
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<p>
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The problem in most versions of IE is that it does not use the mime type on
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the HTTP response to determine the file type; rather it uses the file extension
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on the request. Thus you might want to add a <strong>.xls</strong> to your request
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string. For example <em>http://yourserver.com/myServelet.xls?param1=xx</em>. This is
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on the request. Thus you might want to add a
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<strong>.xls</strong> to your request
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string. For example
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<em>http://yourserver.com/myServelet.xls?param1=xx</em>. This is
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easily accomplished through URL mapping in any servlet container. Sometimes
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a request like <em>http://yourserver.com/myServelet?param1=xx&dummy=file.xls</em> is also
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known to work.
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a request like
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<em>http://yourserver.com/myServelet?param1=xx&dummy=file.xls</em> is also
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known to work.
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</p>
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<p>
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To guarantee opening the file properly in Excel from IE, write out your file to a
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To guarantee opening the file properly in Excel from IE, write out your file to a
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temporary file under your web root from your servelet. Then send an http response
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to the browser to do a client side redirection to your temp file. (If you do a
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server side redirect using RequestDispatcher, you will have to add .xls to the
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to the browser to do a client side redirection to your temp file. (If you do a
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server side redirect using RequestDispatcher, you will have to add .xls to the
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request as mentioned above.)
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</p>
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<p>
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Note also that when you request a document that is opened with an
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Note also that when you request a document that is opened with an
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external handler, IE sometimes makes two requests to the webserver. So if your
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generating process is heavy, it makes sense to write out to a temporary file, so that multiple
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requests happen for a static file.
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requests happen for a static file.
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</p>
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<p>
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None of this is particular to Excel. The same problem arises when you try to
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generate any binary file dynamically to an IE client. For example, if you generate
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pdf files using <link href="http://xml.apache.org/fop">FOP</link>, you will come across many of the same issues.
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pdf files using
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<link href="http://xml.apache.org/fop">FOP</link>, you will come across many of the same issues.
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</p>
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<!-- Thanks to Avik for the answer -->
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</answer>
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@ -130,13 +137,24 @@
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I want to set a cell format (Data format of a cell) of a excel sheet as###,###,###.#### or ###,###,###.0000. Is it possible using POI ?
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</question>
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<answer>
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HSSF does not yet support custom data formats, however, it should be a
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reasonably easy facillity to add and we'll gladly accept contributions
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in this area.
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<p>
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HSSF does not yet support custom data formats, however, it should be a
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reasonably easy facillity to add and we'll gladly accept contributions
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in this area.
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These are the built in formats that it does support:
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These are the built in formats that it does support:
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<link href="http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFDataFormat_java.html#HSSFDataFormat">http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFDataFormat_java.html#HSSFDataFormat</a>
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<link href="http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFDataFormat_java.html#HSSFDataFormat">http://jakarta.apache.org/poi/javadocs/javasrc/org/apache/poi/hssf/usermodel/HSSFDataFormat_java.html#HSSFDataFormat</link>
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</p>
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</answer>
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</faq>
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<faq>
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<question>
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How do I add a border around a merged cell?
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</question>
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<answer>
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Add blank cells around where the cells normally would have been and set the borders individually for each cell.
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</answer>
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</faq>
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</faqs>
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