自定义标签 taglib的使用

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一首先写个类继承 TagSupport

package com.tagtest.test;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;

public class TimerTag extends TagSupport {
long start;

@Override
public int doStartTag() throws JspException {
start = System.currentTimeMillis();

return EVAL_BODY_INCLUDE;

}

@Override
public int doEndTag() throws JspException {
long duration = System.currentTimeMillis() - start;
JspWriter out = pageContext.getOut();
try {
out.println(duration);
} catch (IOException e) {
e.printStackTrace();
}

return EVAL_PAGE;

}
}

新建一个 .tld结尾的配置文件放在web-inf 这个文件可以去 tomcat webapp web-inf 下的 jsp2 里面copy

<?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>A tag who can caculate time</description>
<tlib-version>1.0</tlib-version>
<short-name>util</short-name>
<uri>http://www.sonppengfei.com/util</uri> //这个非常重要
<tag>
<description>caculate time</description>
<name>timer</name>
<tag-class>com.tagtest.test.TimerTag</tag-class>//这个非常重要
<body-content>JSP</body-content>
</tag>
</taglib>

在页面中去使用

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="song" uri="http://www.sonppengfei.com/util" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>

<body>
This is my JSP page. <br>
</body>
<song:timer>
<%
for(int i = 0;i<100000000;i++){
}

%>

</song:timer>
</html>

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