xpath_getelembyid.html
来自「java类库详细讲解」· HTML 代码 · 共 184 行
HTML
184 行
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<TITLE>Finding Elements by Id in a DOM Document Using XPath
(Java Developers Almanac Example)
</TITLE>
<META CONTENT="Patrick Chan" NAME="AUTHOR">
<META CONTENT="Code Examples from The Java Developers Almanac 1.4" NAME="DESCRIPTION">
<META CONTENT="Addison-Wesley/Patrick Chan" NAME="OWNER">
<META CONTENT="3/20/02" NAME="revision">
<STYLE TYPE="text/css">
<!-- BODY CODE {font-family: Courier, Monospace; font-size: 11pt} TABLE, BODY {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 10pt} PRE {font-family: Courier, Monospace; font-size: 10pt} H3 {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 11pt} A.eglink {text-decoration: none} A:hover.eglink {text-decoration: underline} -->
</STYLE>
</HEAD>
<BODY>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD rowspan="3"><A HREF="/?l=ex"><IMG BORDER="0" ALIGN="BOTTOM" HSPACE="10" SRC="/egs/almanac14a.jpg"></A></TD><TD VALIGN="top"><font face="Times" size="6"><b>The Java Developers Almanac 1.4</b></font>
<br>
Order this book from <a href="/cgi-bin/scripts/redirect.pl?l=ex&url=http://www.amazon.com/exec/obidos/ASIN/0201752808/xeo">Amazon</a>.
</TD>
</TR>
<TR>
<TD align="right" valign="bottom">
<FORM method="get" action="/cgi-bin/search/find.pl">
<INPUT size="25" name="words" type="text"><INPUT value="Search" type="submit">
</FORM>
</TD>
</TR>
</TABLE>
<HR color="#6666cc">
<DIV ALIGN="LEFT">
<A HREF="/">Home</A>
>
<A HREF="../index.html">List of Packages</A>
>
<B><A HREF="../org.w3c.dom/pkg.html">org.w3c.dom</A></B><font color="#666666" SIZE="-2">
[30 examples]
</font>
>
<B><A HREF="../org.w3c.dom/pkg.html#XPath">XPath</A></B><font color="#666666" SIZE="-2">
[5 examples]
</font>
</DIV><P>
<h3>
e551.
Finding Elements by Id in a DOM Document Using XPath</h3>
XPath is an expression language for selecting nodes in an XML file.
See <a href="../org.w3c.dom/xpath_GetAbsElem.html" class="eglink"><font size="-1"><b>e548</b> Finding Elements by Absolute Location in a DOM Document Using XPath</font></a> for common XPath
expression for selecting elements. This example adds to those
examples by demonstrating the ability to select elements based on their
id.
<P> The DTD of an XML file may declare that a certain attribute of
an element is a <font color="#0066ff"><i>unique id</i></font>. An attribute designated as such can
contain any value but no two id attributes can have the same value.
<P> This example demonstrates some common uses of expressions that
use element ids; for more information on XPath, see the specification
at <a href="http://www.w3c.org/TR/xpath"><font size="-1">http://www.w3c.org/TR/xpath</font></a>. In the example, the result of
an XPath expression is shown next to the expression; the numbers are
ids of elements in the sample file shown at the end of the example.
<pre>
// Get element id 3
String xpath = "id('3')"; // 3
// Get all e elements directly under element id 3
xpath = "id('two')/e"; // 3 4 6
// Get elements with id='two', id='3', or id='seven'
xpath = "id('two 3 seven the fifth')"; // two 3 seven
// Note that this method of finding elements does not work
// if the id value contains a space
// Get a non-existent element
xpath = "id('100')"; // (none)
</pre>
To execute an XPath expression, see
<a href="../org.w3c.dom/xpath_GetAbsElem.html" class="eglink"><font size="-1"><b>e548</b> Finding Elements by Absolute Location in a DOM Document Using XPath</font></a>. Here is the sample XML file
used in the example:
<pre>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE root [ <!ELEMENT e (e*) >
<!ATTLIST e id ID #REQUIRED>
]>
<root>
<e id="1">
<e id="two">
<e id="3"/>
<e id="4">
<e id="the fifth"/>
</e>
<e id="6"/>
</e>
</e>
<e id="seven"/>
</root>
</pre>
<P><table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td bgcolor="#6666cc" align="center"><font color="#ffffff">
Related Examples
</font></td>
</tr>
</table>
e548. <a class="eglink" href="xpath_GetAbsElem.html?l=rel">
Finding Elements by Absolute Location in a DOM Document Using XPath
</a>
<br>
e549. <a class="eglink" href="xpath_GetChildElem.html?l=rel">
Selecting from a Set of Child Elements in a DOM Document Using XPath
</a>
<br>
e550. <a class="eglink" href="xpath_GetElemByText.html?l=rel">
Finding Elements by Content in a DOM Document Using XPath
</a>
<br>
e552. <a class="eglink" href="xpath_GetElemByAttr.html?l=rel">
Finding Elements by Attributes in a DOM Document Using XPath
</a>
<br>
<table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td align="left">
<br>
See also:
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Adding%20and%20Removing%20Nodes">
Adding and Removing Nodes
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Element%20Attributes">
Element Attributes
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Elements">
Elements
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Getting%20Nodes">
Getting Nodes
</a>
<a class="eglink" href="/egs/org.w3c.dom/pkg.html?l=rel#Text%20Nodes">
Text Nodes
</a>
</td>
</tr>
</table>
<br>
<br>
<FONT FACE="Verdana, Arial, Helvetica, sans-serif" SIZE="0">
© 2002 Addison-Wesley.
</FONT>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?