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<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <title>XML Tags</title> <link rel="StyleSheet" href="document.css" type="text/css" media="all" /> <link rel="StyleSheet" href="catalog.css" type="text/css" media="all" /> <link rel="Table of Contents" href="J2EETutorialTOC.html" /> <link rel="Previous" href="JSTL4.html" /> <link rel="Next" href="JSTL6.html" /> <link rel="Index" href="J2EETutorialIX.html" /> </head> <body> <table width="550" summary="layout" id="SummaryNotReq1"> <tr> <td align="left" valign="center"> <font size="-1"> <a href="http://java.sun.com/j2ee/1.4/download.html#tutorial" target="_blank">Download</a> <br> <a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/faq.html" target="_blank">FAQ</a> <br> <a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/history.html" target="_blank">History</a> </td> <td align="center" valign="center"><a accesskey="p" href="JSTL4.html"><img id="LongDescNotReq1" src="images/PrevArrow.gif" width="26" height="26" border="0" alt="Prev" /></a><a accesskey="c" href="J2EETutorialFront.html"><img id="LongDescNotReq1" src="images/UpArrow.gif" width="26" height="26" border="0" alt="Home" /></a><a accesskey="n" href="JSTL6.html"><img id="LongDescNotReq3" src="images/NextArrow.gif" width="26" height="26" border="0" alt="Next" /></a><a accesskey="i" href="J2EETutorialIX.html"></a> </td> <td align="right" valign="center"> <font size="-1"> <a href="http://java.sun.com/j2ee/1.4/docs/api/index.html" target="_blank">API</a> <br> <a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/search.html" target="_blank">Search</a> <br> <a href="http://java.sun.com/j2ee/1.4/docs/tutorial/information/sendusmail.html" target="_blank">Feedback</a></font> </font> </td> </tr> </table> <img src="images/blueline.gif" width="550" height="8" ALIGN="BOTTOM" NATURALSIZEFLAG="3" ALT="Divider"> <blockquote><a name="wp63716"> </a><h2 class="pHeading1">XML Tags</h2><a name="wp64237"> </a><p class="pBody">A key aspect of dealing with XML documents is to be able to easily access their content. XPath, a W3C recommendation since 1999, provides an easy notation for specifying and selecting parts of an XML document. The JSTL XML tag set, listed in <a href="JSTL5.html#wp84113">Table 14-5</a>, is based on XPath (see <a href="JAXPXSLT3.html#wp72547">How XPath Works</a>).</p><div align="left"><table border="1" summary="XML Tags" id="wp84113"> <caption><a name="wp84113"> </a><div class="pTableTitle">Table 14-5 XML Tags </div></caption> <tr align="center"> <th><a name="wp84121"> </a><div class="pCellHeading">Area</div></th> <th><a name="wp84123"> </a><div class="pCellHeading">Function</div></th> <th><a name="wp84125"> </a><div class="pCellHeading">Tags</div></th> <th><a name="wp84127"> </a><div class="pCellHeading">Prefix</div></th></tr> <tr align="left"> <td colspan="1" rowspan="3"><a name="wp84129"> </a><div class="pCellBody">XML</div></td> <td><a name="wp84131"> </a><div class="pCellBody">Core</div></td> <td><a name="wp84133"> </a><div class="pCellBody"><code class="cCode">out</code></div><a name="wp84134"> </a><div class="pCellBody"><code class="cCode">parse</code></div><a name="wp84135"> </a><div class="pCellBody"><code class="cCode">set</code></div></td> <td colspan="1" rowspan="3"><a name="wp84137"> </a><div class="pCellBody"><code class="cCode">x</code></div></td></tr> <tr align="left"> <td><a name="wp84141"> </a><div class="pCellBody">Flow Control</div></td> <td><a name="wp84143"> </a><div class="pCellBody"><code class="cCode">choose</code></div><a name="wp84144"> </a><div class="pCellBody"><code class="cCode"> when</code></div><a name="wp84145"> </a><div class="pCellBody"><code class="cCode"> otherwise</code></div><a name="wp84146"> </a><div class="pCellBody"><code class="cCode">forEach</code></div><a name="wp84147"> </a><div class="pCellBody"><code class="cCode">if</code></div></td></tr> <tr align="left"> <td><a name="wp84153"> </a><div class="pCellBody">Transformation</div></td> <td><a name="wp84155"> </a><div class="pCellBody"><code class="cCode">transform</code></div><a name="wp84156"> </a><div class="pCellBody"><code class="cCode"> param</code></div></td></tr></table></div><p class="pBody"></p><a name="wp64247"> </a><p class="pBody">The XML tags use XPath as a <em class="cEmphasis">local</em> expression language; XPath expressions are always specified using attribute <code class="cCode">select</code>. This means that only values specified for <code class="cCode">select</code> attributes are evaluated using the XPath expression language. All other attributes are evaluated using the rules associated with the JSP 2.0 expression language.</p><a name="wp81640"> </a><p class="pBody">In addition to the standard XPath syntax, the JSTL XPath engine supports the following scopes to access Web application data within an XPath expression:</p><div class="pSmartList1"><ul class="pSmartList1"><a name="wp81644"> </a><div class="pSmartList1"><li><code class="cCode">$foo</code></li></div><a name="wp76356"> </a><div class="pSmartList1"><li><code class="cCode">$param:</code></li></div><a name="wp76314"> </a><div class="pSmartList1"><li><code class="cCode">$header:</code></li></div><a name="wp76315"> </a><div class="pSmartList1"><li><code class="cCode">$cookie:</code></li></div><a name="wp76316"> </a><div class="pSmartList1"><li><code class="cCode">$initParam:</code></li></div><a name="wp76317"> </a><div class="pSmartList1"><li><code class="cCode">$pageScope:</code></li></div><a name="wp76320"> </a><div class="pSmartList1"><li><code class="cCode">$requestScope:</code></li></div><a name="wp76323"> </a><div class="pSmartList1"><li><code class="cCode">$sessionScope:</code></li></div><a name="wp76326"> </a><div class="pSmartList1"><li><code class="cCode">$applicationScope:</code></li></div></ul></div><a name="wp76808"> </a><p class="pBody">These scopes are defined in exactly the same way as their counterparts in the JSP expression language discussed in <a href="JSPIntro7.html#wp71043">Implicit Objects</a>. <a href="JSTL5.html#wp76812">Table 14-6</a> shows some examples of using the scopes.</p><div align="left"><table border="1" summary="Example XPath Expressions" id="wp76812"> <caption><a name="wp76812"> </a><div class="pTableTitle">Table 14-6 Example XPath Expressions</div></caption> <tr align="center"> <th><a name="wp76816"> </a><div class="pCellHeading">XPath Expression</div></th> <th><a name="wp76818"> </a><div class="pCellHeading">Result</div></th></tr>⌨️ 快捷键说明
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