jsp自定义标签的例子

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jsp:

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%><%@ taglib uri="/WEB-INF/MyTag.tld" prefix="cc"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <title>My JSP 'tagone.jsp' starting page</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>  <cc:iterator count="10">Hello world jsp taglib !!!</cc:iterator>  </body></html>

web.xml：

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <display-name></display-name>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list>  <jsp-config>    <taglib>  <taglib-uri>/WEB-INF/MyTag.tld</taglib-uri>  <taglib-location>/WEB-INF/MyTag.tld</taglib-location>    </taglib>  </jsp-config></web-app>

MyTag.tld

<?xml version="1.0" encoding="UTF-8"?> <taglib>    <tlibversion>1.0</tlibversion>    <jspversion>1.1</jspversion>         <tag>     <name>iterator</name>     <tagclass>com.zyujie.util.MyTag</tagclass>     <bodycontent>jsp</bodycontent>     <!-- 定义属性 -->     <attribute>        <name>count</name> <!-- 属性名字 -->        <type>int</type>  <!-- 属性类型 -->        <requried>false</requried> <!-- 是否必须 -->        <rtexprvale>false</rtexprvale> <!-- 表示是否可以使用JSP表达式  -->   </attribute>   </tag> </taglib>

MyTag.class

package com.zyujie.util;import java.io.IOException;import java.util.Date;import javax.servlet.http.HttpServletRequest;import javax.servlet.jsp.JspException;import javax.servlet.jsp.JspWriter;import javax.servlet.jsp.tagext.BodyContent;import javax.servlet.jsp.tagext.BodyTagSupport;public class MyTag extends BodyTagSupport {//执行顺序////doStartTag()->setBodyContent()->doInitBody()->doAfterTag()->doEndTag()////如果doStartTag()返回的是EVAL_BODY_INCLUDE执行doAfterTag()方法,////如果它返回SKIP_BODY就执行doEndTag()方法。////setBodyContent()方法用于设置标签体内容，如果在计算BodyContent时需要进行一些初始化工作，////则在doInitBody()方法中完成。标签体内容执行完后，会调用doAfterBody()方法////在doAfterTag()方法中返回EVAL_BODY_AGAIN来重复执行doAfterTag()方法////返回SKIP_BODY值则执行doEndTag()方法。////在doEndTag()方法中返回EVAL_PAGE值,则执行此标签的后的其它代码,////返回SKIP_PAGE则不执行此页面的其它代码。private int count;private HttpServletRequest reqeust;private JspWriter out;public void init() {reqeust = (HttpServletRequest) pageContext.getRequest();out = pageContext.getOut();}@Overridepublic int doStartTag() throws JspException {init();return this.EVAL_BODY_INCLUDE;}// 设置当前标签体@Overridepublic void setBodyContent(BodyContent bodyContent) {this.bodyContent = bodyContent;System.out.println("setBodyContent...");}// 需要初始化bodyContent@Overridepublic void doInitBody() throws JspException {System.out.println("init.....");}@Overridepublic int doAfterBody() throws JspException {if (count >= 1) {try {out.println(count);out.println("<Br>");} catch (IOException e) {e.printStackTrace();}count--;return this.EVAL_BODY_AGAIN;} else {return this.SKIP_BODY;}}@Overridepublic int doEndTag() throws JspException {java.text.SimpleDateFormat formater = new java.text.SimpleDateFormat("yyyy-MM-dd");String date = formater.format(new Date());try {out.print(date);} catch (IOException e) {e.printStackTrace();}return this.EVAL_PAGE;}// 必须实现setXX()方法public void setCount(int count) {this.count = count;}}

完成。。。

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