javaweb中實如今線人數統計

時間 2019-11-05

標籤 javaweb 如今線人統計欄目 Java 简体版

原文原文鏈接

session並非瀏覽器關閉時銷燬的，而是在session失效的時候銷燬下列代碼就是監測session建立、銷燬css

package com.my.count;

import javax.servlet.http.*;

public class SessionCounter implements HttpSessionListener {

    private static int activeSessions = 0;
    //session建立時執行
    public void sessionCreated(HttpSessionEvent se) {
        activeSessions++;
    }
    //session銷燬時執行
    public void sessionDestroyed(HttpSessionEvent se) {
        if (activeSessions > 0)
            activeSessions--;
    }
    //獲取活動的session個數(在線人數)
    public static int getActiveSessions() {
        return activeSessions;
    }

}

接下來就是配置web.xmlhtml

<listener>
      <listener-class>
          com.my.count.SessionCounter  //這裏是包名加類名
      </listener-class>
  </listener>

接下來就能夠在jsp頁面中使用java

<%@ 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>
        在線人數爲：<%=SessionCounter.getActiveSessions() %>
  </body>
</html>