jsp 实现在线人数统计

首先写个类:

    import javax.servlet.*;

    import javax.servlet.http.*;

    public class SessionCounter implements HttpSessionListener {

    private static int activeSessions = 0;

    public void sessionCreated(HttpSessionEvent se) {

    activeSessions++;

    }

    public void sessionDestroyed(HttpSessionEvent se) {

    if(activeSessions 0)

    activeSessions--;

    }

    public static int getActiveSessions() {

    return activeSessions;

    }

    }

    然后配置web.xml

    ？xml version="1.0" encoding="UTF-8"？

    web-app version="2.4"

    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-app_2_4.xsd"

    ****************************************

    !-- Listeners --

    listener

    listener-class

    SessionCount.SessionCounter (注意此处)

    /listener-class

    /listener

    *****************************************

    /web-app

建个JSP测试:

    test.jsp

    %@ page language="Java" contentType="text/html;charset=GBK"%

    %@ page import="java.sql.*"%

    %@ page import="SessionCount.SessionCounter" %

    html

    head

    meta http-equiv="Content-Type" content="text/html; charset=GBK"

    title无标题文档/title

    body bgcolor="#FFFFFF"

    在线人数:%=SessionCounter.getActiveSessions()%

    /body

    /html

    看看可以实现不？我也是找到的,我用了,可以统计出来.