javaweb中實現線上人數統計
阿新 • • 發佈：2019-01-04
session並不是瀏覽器關閉時銷燬的，而是在session失效的時候銷燬下列程式碼就是監測session建立、銷燬
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(線上人數) public static int getActiveSessions() { return activeSessions; } }
接下來就是配置web.xml
<listener>
<listener-class>
com.my.count.SessionCounter //這裡是包名加類名
</listener-class>
</listener>接下來就可以在jsp頁面中使用
<%@ 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> 線上人數為：<%=SessionCounter.getActiveSessions() %> </body> </html>
不用jsp頁面 寫成介面程式碼如下:
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(線上人數)
public static int getActiveSessions() {
return activeSessions;
}
} /**
* 線上使用者人數
* @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();
}