session并不是浏览器关闭时销毁的，而是在session失效的时候销毁下列代码就是监测session创建、销毁
package com.my.count; import javax.servlet.http.*; public class SessionCounter implements HttpSessionListener { private static int activeSessions = 0; //session创建时执行 public void sessionCreated(HttpSessionEvent se) { activeSessions++; } //session销毁时执行 public void sessionDestroyed(HttpSessionEvent se) { if (activeSessions > 0) activeSessions--; } //获取活动的session个数(在线人数) public static int getActiveSessions() { return activeSessions; } }
接下来就是配置web.xml
<listener> <listener-class> com.my.count.SessionCounter //这里是包名加类名 </listener-class> </listener>
接下来就可以在jsp页面中使用
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@ page import="com.my.count.SessionCounter"%> <% 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 'ApplicationTest.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> 在线人数为：<%=SessionCounter.getActiveSessions() %> </body> </html>