javaweb中实现在线人数统计

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>

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javaweb中实现在线人数统计

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