自定义标签

1.标签处理类,继承BodyTagSupport

 

package com.nanjing.testTag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class MyTag extends BodyTagSupport{

	private boolean test;
	
	public void setTest(boolean test) {
		this.test = test;
	}

	@Override
	public int doEndTag() throws JspException {
		if(test){
			try {
				pageContext.getOut().write("hello world!");
			} catch (IOException e) {
				e.printStackTrace();
			}
			return EVAL_PAGE;
		}else{
			throw new JspTagException("not limit false!");
		}

	}

	@Override
	public void doInitBody() throws JspException {
		super.doInitBody();
	}

	@Override
	public int doStartTag() throws JspException{
		
		return EVAL_BODY_INCLUDE;
	}
	
}

 

2.定义tld文件,放在WEB-INF下即可

 

<?xml version="1.0" encoding="UTF-8" ?>

<taglib 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 http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
    version="2.0">
    
  <description>test library</description>
  <display-name>test core</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>alyssa</short-name>
  <uri>http://nanjing.alyssa.com.cn</uri>

  <tag>
    <description>
	Subtag of &lt;choose&gt; that includes its body if its
	condition evalutes to 'true'
    </description>
    <name>hello</name>
    <tag-class>com.nanjing.testTag.MyTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <description>
The test condition that determines whether or not the
body content should be processed.
        </description>
        <name>test</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
		<type>boolean</type>
    </attribute>
  </tag>

</taglib>

 3.测试页面

 

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib prefix="alyssa"  uri="http://nanjing.alyssa.com.cn"%>
<!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">
<title>Insert title here</title>
</head>
<body>
	<alyssa:hello test="true"></alyssa:hello>
</body>
</html>
 

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