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<img alt="掌握自定义 JSP 标签" src="imagemaster/masthead.jpg"></td><td width="*" valign="bottom" align="right"><a border="0" href="j-customtags.zip"><img alt="下载 ZIP 文件" border="0" src="../i/icon-zip.gif"></a><a target="_blank" href="../tutorial_eng/index.html" border="0"><img alt="英文原文" border="0" src="../i/icon-source.gif"></a>
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<a name="navskip"></a><td height="25" colspan="4"><img alt="3.简单标签" src="imagemaster/titlebar3.jpg" border="0" height="25" width="562"></td>
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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>简单标签的例子</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr> 第 1 页（共9 页）</nobr></font></td>
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Struts 框架带有几个自定义标签库（有关 Struts 的更多信息的链接请参阅 <a href="j-customtags-7-2.html">参考资料</a> ）。这些库中的一个标签可以创建一个支持改写 URL 的链接并用 <code>jsessionid</code> 对改写的连接编码。
</p>
<p>
不过有一个问题：如果希望传递一组请求参数（如查询字符串），也许必须为此创建一个 Java scriptlet。真是乱！下面的清单 （search_results.jap） 展示了一个 JSP 页，它被迫加入了这样一个 scriptlet。
</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
<%@ taglib uri="struts-html" prefix="html" %>
<jsp:useBean class="java.util.HashMap" id="deleteParams" />
<%
deleteParams.put("id", cd.getId());
deleteParams.put("method","delete");
%>
<!-- Pass the map named deleteParams to html:link to generate
the request parameters-->
<html:link action="/deleteCD" name="deleteParams">delete </html:link> </font></td>
</code>
</pre>
<p>
search_results.jsp 创建一个 hashmap 并向这个 map 传递两个属性。在下面几小节，我们将创建一个不用 Java 代码完成这项工作的自定义标签。我们的标签将定义如下的一个 hashmap：
</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
<map:mapDefine id="deleteParams">
<map:mapEntry id="id" name="cd" property="id"/>
<map:mapEntry id="method" value="delete"/>
</map:mapDefine>
<!-- Pass the map named deleteParams to html:link to generate
the request parameters-->
<html:link action="/deleteCD" name="deleteParams">delete </html:link> </font></td>
</code>
</pre>
<p>
这将使我们可以容易地创建小型 map。
</p>
<p>
这个例子将展示几个关键概念，包括使用嵌套标签和定义 scriplet 变量。首先我将解释这个标签是如何工作的。然后在以后的几节中建立这些概念，并介绍如何编写这个标签的不同形式，使它们处理其正文并控制执行流程。
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