Javaweb实现在线人数统计代码实例

时间:2021-04-02 人气:0

这篇文章主要介绍了Javaweb实现在线人数统计代码实例,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

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%>" rel="external nofollow" >
  
  <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" rel="external nofollow" >
  -->

 </head>
 
 <body>
    在线人数为：<%=SessionCounter.getActiveSessions() %>
 </body>
</html>

不用jsp页面写成接口代码如下:

package com.wangyun.web.controllers;

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class SessionCounter implements HttpSessionListener {

   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;
  }

}

  /**
 	 * 在线用户人数
 	 * @throws IOException 
 	 * @throws ServletException 
 	 */
   @RequestMapping(value="user_online", method=RequestMethod.POST, produces="text/json;charset=utf-8")
 	@ResponseBody
 	public Object user_online() throws ServletException, IOException {
 			JSONObject data = new JSONObject();
 			int number=SessionCounter.activeSessions;
 			data.put("msg",number);
 			return data.toString();
   }

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