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自定义带属性和标签体的标签,结构为:java–tld–jsp
MyTag4.java
package cn.wang.tag;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class MyTag4 extends SimpleTagSupport {
private boolean test;
/*
* 这个方法由tomcat调用,在doTag()之前
*/
public void setTest(boolean test) {
this.test = test;
}
@Override
public void doTag() throws JspException, IOException {
if (test) {
this.getJspBody().invoke(null);//如果test为真,则输出标签体内容
}
}
}
wang.cn.tld
<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.0" xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd">
<tlib-version>1.0</tlib-version>
<short-name>wang</short-name>
<tag>
<name>MyTag4</name>
<!-- java文件的路径 -->
<tag-class>cn.wang.tag.MyTag4</tag-class>
<!--标签体的类型(html&el) -->
<body-content>scriptless</body-content>
<attribute>
<!-- 属性的名称 -->
<name>test</name>
<!-- 是否为必填 -->
<required>true</required>
<!--是否支持el表达式,一般为true -->
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%>
<%@taglib prefix="wang" uri="/WEB-INF/tlds/wang.cn.tld"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>自定义标签</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<wang:MyTag4 test="${1==1}">执行了标签体</wang:MyTag4>
</body>
</html>
知识补充:在自定义标签中中断可使用: throw new SkipPageException();
底层的servlet并不抛出该异常,在catch中对该异常进行了单独的 处理,实现后面的所有标签全不执行,如图。