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自定义JSP标签库实现

最新推荐文章于 2025-05-10 21:50:15 发布

原创最新推荐文章于 2025-05-10 21:50:15 发布 · 123 阅读

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usertag.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>
<jsp-version>2.0</jsp-version>
<short-name>baoyou</short-name>
<uri>/usertag</uri>
<tag>
    <name>userinfo</name>
    <tag-class>com.baoyou.test.autotag.UserTag</tag-class>
    <body-content>empty</body-content>
    <attribute>
        <name>user</name>
         <required>false</required>
         <rtexprvalue>true</rtexprvalue>
    </attribute>
 </tag>
</taglib>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:javaee="http://java.sun.com/xml/ns/javaee"
	xmlns:jsp="http://java.sun.com/xml/ns/javaee/jsp" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
	id="WebApp_9" version="2.4">
	 
	 
   <jsp-config> 
     <taglib> 
        <taglib-uri>/usertag</taglib-uri> 
        <taglib-location>/WEB-INF/usertag.tld</taglib-location> 
     </taglib> 
   </jsp-config>
	 
</web-app>

public class User {

	private int userId;
	private String username;
	private String password;
	
	public int getUserId() {
		return userId;
	}
	public void setUserId(int userId) {
		this.userId = userId;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	 
}

package com.baoyou.test.autotag;
 

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

public class UserTag extends TagSupport{
 
	private static final long serialVersionUID = 1L;
	
	private User user;
	 
	@Override
	public int doStartTag() throws JspException { 
		 JspWriter out = this.pageContext.getOut();
		 try{
		 if (user == null) { 
				out.println("No UserInfo Found...");
		 }
		 out.println("<table width='500px' border='1' align='center'>");
         out.println("<tr>");
         out.println("<td width='20%'>userid:</td>");
         out.println("<td>" + user.getUserId() + "</td>");
         out.println("</tr>");
         out.println("<tr>");
         out.println("<td>username:</td>");
         out.println("<td>" + user.getUsername() + "</td>");
         out.println("</tr>");
         out.println("<tr>");
         out.println("<td>password:</td>");
         out.println("<td>" + user.getPassword() + "</td>");
         out.println("</tr>");
         out.println("</table>");
		 }catch(Exception e){
			 throw  new JspException(e.getMessage());
		 }
		return SKIP_BODY;
	}
	
	@Override
	public int doEndTag() throws JspException { 
		 return EVAL_PAGE;
	}
	public User getUser() {
		return user;
	}
	public void setUser(User user) {
		this.user = user;
	}
}

<%@ page language="java" import="java.util.*,com.baoyou.test.autotag.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ taglib uri="/usertag" prefix="baoyou"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head> 
    <title>My JSP 'index.jsp' starting page</title> 
  </head> 
  <body>
  <% User user = new User(); 
 	 user.setUserId(1);
 	 user.setUsername("baoyou");
 	 user.setPassword("baoyou"); 
     pageContext.setAttribute("userinfo", user);      %>
   <baoyou:userinfo user="${pageScope.userinfo }" />
  </body>
</html>