<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<!--*** This is a generated file. Do not edit. ***-->
<link rel="stylesheet" href="../skin/tigris.css" type="text/css">
<link rel="stylesheet" href="../skin/mysite.css" type="text/css">
<link rel="stylesheet" href="../skin/site.css" type="text/css">
<link media="print" rel="stylesheet" href="../skin/print.css" type="text/css">
<title>POI-HSSF and POI-XSSF - Java API To Access Microsoft Excel Format Files</title>
</head>
<body bgcolor="white" class="composite">
<!--================= start Banner ==================-->
<div id="banner">
<table width="100%" cellpadding="8" cellspacing="0" summary="banner" border="0">
<tbody>
<tr>
<!--================= start Group Logo ==================-->
<td width="50%" align="left">
<div class="groupLogo">
<a href="http://poi.apache.org"><img border="0" class="logoImage" alt="Apache POI" src="../resources/images/group-logo.jpg"></a>
</div>
</td>
<!--================= end Group Logo ==================-->
<!--================= start Project Logo ==================--><td width="50%" align="right">
<div align="right" class="projectLogo">
<a href="http://poi.apache.org/"><img border="0" class="logoImage" alt="POI" src="../resources/images/project-logo.jpg"></a>
</div>
</td>
<!--================= end Project Logo ==================-->
</tr>
</tbody>
</table>
</div>
<!--================= end Banner ==================-->
<!--================= start Main ==================-->
<table width="100%" cellpadding="0" cellspacing="0" border="0" summary="nav" id="breadcrumbs">
<tbody>
<!--================= start Status ==================-->
<tr class="status">
<td>
<!--================= start BreadCrumb ==================--><a href="http://www.apache.org/">Apache</a> | <a href="http://poi.apache.org/">POI</a><a href=""></a>
<!--================= end BreadCrumb ==================--></td><td id="tabs">
<!--================= start Tabs ==================-->
<div class="tab">
<span class="selectedTab"><a class="base-selected" href="../index.html">Home</a></span> | <script language="Javascript" type="text/javascript">
function printit() {
if (window.print) {
window.print() ;
} else {
var WebBrowser = '<OBJECT ID="WebBrowser1" WIDTH="0" HEIGHT="0" CLASSID="CLSID:8856F961-340A-11D0-A96B-00C04FD705A2"></OBJECT>';
document.body.insertAdjacentHTML('beforeEnd', WebBrowser);
WebBrowser1.ExecWB(6, 2);//Use a 1 vs. a 2 for a prompting dialog box WebBrowser1.outerHTML = "";
}
}
</script><script language="Javascript" type="text/javascript">
var NS = (navigator.appName == "Netscape");
var VERSION = parseInt(navigator.appVersion);
if (VERSION > 3) {
document.write(' <a title="PRINT this page OUT" href="javascript:printit()">PRINT</a>');
}
</script>
</div>
<!--================= end Tabs ==================-->
</td>
</tr>
</tbody>
</table>
<!--================= end Status ==================-->
<table id="main" width="100%" cellpadding="8" cellspacing="0" summary="" border="0">
<tbody>
<tr valign="top">
<!--================= start Menu ==================-->
<td id="leftcol">
<div id="navcolumn">
<div class="menuBar">
<div class="menu">
<span class="menuLabel">Apache POI</span>
<div class="menuItem">
<a href="../index.html">Top</a>
</div>
</div>
<div class="menu">
<span class="menuLabel">HSSF+XSSF</span>
<div class="menuItem">
<span class="menuSelected">Overview</span>
</div>
<div class="menuItem">
<a href="quick-guide.html">Quick Guide</a>
</div>
<div class="menuItem">
<a href="how-to.html">HOWTO</a>
</div>
<div class="menuItem">
<a href="converting.html">HSSF to SS Converting</a>
</div>
<div class="menuItem">
<a href="formula.html">Formula Support</a>
</div>
<div class="menuItem">
<a href="eval.html">Formula Evaluation</a>
</div>
<div class="menuItem">
<a href="eval-devguide.html">Eval Dev Guide</a>
</div>
<div class="menuItem">
<a href="examples.html">Examples</a>
</div>
<div class="menuItem">
<a href="use-case.html">Use Case</a>
</div>
<div class="menuItem">
<a href="diagrams.html">Pictorial Docs</a>
</div>
<div class="menuItem">
<a href="limitations.html">Limitations</a>
</div>
<div class="menuItem">
<a href="user-defined-functions.html">User Defined Functions</a>
</div>
<div class="menuItem">
<a href="excelant.html">ExcelAnt Tests</a>
</div>
</div>
<div class="menu">
<span class="menuLabel">Contributer's Guide</span>
<div class="menuItem">
<a href="hacking-hssf.html">Hacking HSSF</a>
</div>
<div class="menuItem">
<a href="record-generator.html">Record Generator</a>
</div>
<div class="menuItem">
<a href="chart.html">Charts</a>
</div>
</div>
</div>
</div>
<form target="_blank" action="http://www.google.com/search" method="get">
<table summary="search" border="0" cellspacing="0" cellpadding="0">
<tr>
<td><img height="1" width="1" alt="" src="../skin/images/spacer.gif" class="spacer"></td><td nowrap="nowrap">
Search Apache POI<br>
<input value="poi.apache.org" name="sitesearch" type="hidden"><input size="10" name="q" id="query" type="text"><img height="1" width="5" alt="" src="../skin/images/spacer.gif" class="spacer"><input name="Search" value="GO" type="submit"></td><td><img height="1" width="1" alt="" src="../skin/images/spacer.gif" class="spacer"></td>
</tr>
<tr>
<td colspan="3"><img height="7" width="1" alt="" src="../skin/images/spacer.gif" class="spacer"></td>
</tr>
<tr>
<td class="bottom-left-thick"></td><td bgcolor="#a5b6c6"><img height="1" width="1" alt="" src="../skin/images/spacer.gif" class="spacer"></td><td class="bottom-right-thick"></td>
</tr>
</table>
</form>
</td>
<!--================= end Menu ==================-->
<!--================= start Content ==================--><td>
<div id="bodycol">
<div class="app">
<div align="center">
<h1>POI-HSSF and POI-XSSF - Java API To Access Microsoft Excel Format Files</h1>
</div>
<div class="h3">
<a name="Overview"></a>
<div class="h3">
<h3>Overview</h3>
</div>
<p>HSSF is the POI Project's pure Java implementation of the
Excel '97(-2007) file format. XSSF is the POI Project's pure
Java implementation of the Excel 2007 OOXML (.xlsx) file
format.</p>
<p>HSSF and XSSF provides ways to read spreadsheets create,
modify, read and write XLS spreadsheets. They provide:
</p>
<ul>
<li>low level structures for those with special needs</li>
<li>an eventmodel api for efficient read-only access</li>
<li>a full usermodel api for creating, reading and modifying XLS files</li>
</ul>
<p>For people converting from pure HSSF usermodel, who wish
to use the joint SS Usermodel for HSSF and XSSF support, then
see the <a href="converting.html">ss usermodel converting
guide</a>.
</p>
<p>
An alternate way of generating a spreadsheet is via the <a href="http://cocoon.apache.org">Cocoon</a> serializer (yet you'll still be using HSSF indirectly).
With Cocoon you can serialize any XML datasource (which might be a ESQL page outputting in SQL for instance) by simply
applying the stylesheet and designating the serializer.
</p>
<p>
If you're merely reading spreadsheet data, then use the
eventmodel api in either the org.apache.poi.hssf.eventusermodel
package, or the org.apache.poi.xssf.eventusermodel package, depending
on your file format.
</p>
<p>
If you're modifying spreadsheet data then use the usermodel api. You
can also generate spreadsheets this way.
</p>
<p>
Note that the usermodel system has a higher memory footprint than
the low level eventusermodel, but have the major advantage of being
much simpler to work with. Also please be aware that as the new
XSSF supported Excel 2007 OOXML (.xlsx) files are XML based,
the memory footprint for processing them is higher than for the
older HSSF supported (.xls) binary files.
</p>
<a name="SXSSF+%28Since+POI+3.8+beta3%29"></a>
<div class="h3">
<h3>SXSSF (Since POI 3.8 beta3)</h3>
</div>
<p>Since 3.8-beta3, POI provides a low-memory footprint SXSSF API built on top of XSSF.</p>
<p>
SXSSF is an API-compatible streaming extension of XSSF to be used when
very large spreadsheets have to be produced, and heap space is limited.
SXSSF achieves its low memory footprint by limiting access to the rows that
are within a sliding window, while XSSF gives access to all rows in the
document. Older rows that are no longer in the window become inaccessible,
as they are written to the disk.
</p>
<p>
In auto-flush mode the size of the access window can be specified, to hold a certain number of rows in memory.
When that value is reached, the creation of an additional row causes the row with the lowest index to to be
removed from the access window and written to disk. Or, the window size can be set to grow dynamically;
it can be trimmed periodically by an explicit call to flushRows(int keepRows) as needed.
</p>
<p>
Due to the streaming nature of the implementation, there are the following
limitations when compared to XSSF:
</p>
<ul>
<li>Only a limited number of rows are accessible at a point in time.</li>
<li>Sheet.clone() is not supported.</li>
<li>Formula evaluation is not supported</li>
</ul>
<p> See more details at <a href="how-to.html#sxssf">SXSSF How-To</a>
</p>
<p>The table below synopsizes the comparative features of POI's Spreadsheet API:</p>
<p>
<em>Spreadsheet API Feature Summary</em>
</p>
<p>
<img alt="Spreadsheet API Feature Summary" src="../resources/images/ss-features.png">
</p>
<div id="authors" align="right">by Andrew C. Oliver, Nicola Ken Barozzi</div>
</div>
</div>
</div>
</td>
<!--================= end Content ==================-->
</tr>
</tbody>
</table>
<!--================= end Main ==================-->
<!--================= start Footer ==================-->
<div id="footer">
<table summary="footer" cellspacing="0" cellpadding="4" width="100%" border="0">
<tbody>
<tr>
<!--================= start Copyright ==================-->
<td colspan="2">
<div align="center">
<div class="copyright">
Copyright © 2002-2012 The Apache Software Foundation. All rights reserved.<br>
Apache POI, POI, Apache, the Apache feather logo, and the Apache
POI project logo are trademarks of The Apache Software Foundation.
</div>
</div>
</td>
<!--================= end Copyright ==================-->
</tr>
<tr>
<td align="left">
<!--================= start Host ==================-->
<!--================= end Host ==================--></td><td align="right">
<!--================= start Credits ==================-->
<div align="right">
<div class="credit">
<a href="http://validator.w3.org/check/referer"><img width="88" height="31" alt="Valid HTML 4.01!" src="../skin/images/valid-html401.png" class="logoImage"></a><a href="http://jigsaw.w3.org/css-validator/"><img width="88" height="31" alt="Valid CSS!" src="../skin/images/vcss.png" class="logoImage"></a><a href="http://forrest.apache.org/"><img border="0" class="logoImage" alt="Built with Apache Forrest" src="../skin/images/built-with-forrest-button.png" width="88" height="31"></a>
</div>
</div>
<!--================= end Credits ==================-->
</td>
</tr>
</tbody>
</table>
</div>
<!--================= end Footer ==================-->
</body>
</html>
