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Step 1 ： 写一个java类，实现SimpleTag接口或继承SimpleTagSupport抽象类
Step 2： 在java类中，override doTag()方法，再该方法中，实现标签的业务逻辑
Step 3： 在tld文件中描述标签。
Step 4： 在JSP页面中，使用taglib指令导入标签
java类：
1 package mytag; 2 3 import java.io.IOException; 4 5 import javax.servlet.jsp.*; 6 import javax.servlet.jsp.tagext.SimpleTagSupport; 7 8 public class HelloTag extends SimpleTagSupport{ 9 10 private String info; 11 private int num; 12 13 public String getInfo() { 14 return info; 15 } 16 17 public void setInfo(String info) { 18 System.out.println("setinfo"); 19 this.info = info; 20 } 21 22 public int getNum() { 23 return num; 24 } 25 26 public void setNum(int num) { 27 System.out.println("setnum"); 28 this.num = num; 29 } 30 31 public HelloTag() { 32 System.out.println("constructor"); 33 } 34 35 @Override 36 public void doTag() throws JspException, IOException { 37 // TODO Auto-generated method stub 38 JspContext jc = getJspContext(); 39 PageContext pc = (PageContext)jc; 40 JspWriter out=pc.getOut(); 41 for(int i=0;i<num;i++){ 42 out.println(info+"<br/>"); 43 } 44 } 45 46 }
mytag.tld文件如下：
<?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>JSTL 1.1 core library</description> <display-name>JSTL core</display-name> <tlib-version>1.1</tlib-version> <short-name>c1</short-name> <uri>http://www.caxa.com/mytag</uri> <tag> <name>sayHello</name> <tag-class>mytag.HelloTag</tag-class> <body-content>empty</body-content> <attribute> <name>info</name> <required>true</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>num</name> <required>true</required> <rtexprvalue>false</rtexprvalue> </attribute> </tag> </taglib>
jsp文件（也就是使用过程）如下：
<%@ page language="java" import="java.util.*,java.lang.*" pageEncoding="ISO-8859-1"%> <%@ taglib prefix="fn1" uri="http://www.caxa.com/fn1" %> <%@ taglib prefix="c1" uri="http://www.caxa.com/mytag" %> <% 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>My JSP ‘MyJsp.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"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <% request.setAttribute("str1","xvgfdgsdfgfdgg"); %> s1:${fn1:toUpperCase(str1)} <c1:sayHello num="100" info="hello world"/> This is my JSP page. <br> </body> </html>
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原文地址：http://www.cnblogs.com/hzzhero/p/5055403.html
