创建一个监听器BListener实现ServletContextAttributeListener接口:
BListener:
package demoListener;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class BListener implements ServletContextAttributeListener {
public void attributeAdded(ServletContextAttributeEvent scae) {
System.out.println("你正在添加一个名为:" + scae.getName() + ",值为:" + scae.getValue() + "的属性内容");
}
public void attributeRemoved(ServletContextAttributeEvent scae) {
System.out.println("你正在删除一个名为:" + scae.getName() + ",值为:" + scae.getValue() + "的属性内容");
}
public void attributeReplaced(ServletContextAttributeEvent scae) {
System.out.println("你正在修改一个名为:" + scae.getName() + ",值为:" + scae.getValue() + "的属性内容");
}
}
创建一个JSP页面:
index.jsp:
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>title</title>
</head>
<body>
<%
application.setAttribute("张三", 15);
application.setAttribute("张三", 14);
application.removeAttribute("张三");
%>
<h1>欢迎来到我的世界</h1>
</body>
</html>
启动服务器 -- 浏览器访问index.jsp:
查看控制台的输出内容:
成功实现了ServletContextAttributeListener属性监听器。