session的使用

简单的实现Session的用法，新建立项目未用到计科院主页。

 

IE浏览器打开效果：

 

Microsoft Edge浏览器打开效果：

FireFox浏览器打开效果：

实现了记录网站在线人数的计算

 

代码：

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <base href="<%=basePath%>">
11     
12     <title>My JSP 'index.jsp' starting page</title>
13     <meta http-equiv="pragma" content="no-cache">
14     <meta http-equiv="cache-control" content="no-cache">
15     <meta http-equiv="expires" content="0">    
16     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
17     <meta http-equiv="description" content="This is my page">
18     <!--
19     <link rel="stylesheet" type="text/css" href="styles.css">
20     -->
21   </head>
22   
23   <body><b>当前在线人数：</b>
24   
25   <%=(Integer)application.getAttribute("Online")%>
26   </body>
27 </html>
index.jsp
 1 package com.a;
 2 
 3 import javax.servlet.ServletContextAttributeEvent;
 4 import javax.servlet.ServletContextAttributeListener;
 5 import javax.servlet.ServletContextEvent;
 6 import javax.servlet.ServletContextListener;
 7 import javax.servlet.ServletRequestAttributeEvent;
 8 import javax.servlet.ServletRequestAttributeListener;
 9 import javax.servlet.ServletRequestEvent;
10 import javax.servlet.ServletRequestListener;
11 import javax.servlet.annotation.WebListener;
12 import javax.servlet.http.HttpSessionActivationListener;
13 import javax.servlet.http.HttpSessionAttributeListener;
14 import javax.servlet.http.HttpSessionBindingEvent;
15 import javax.servlet.http.HttpSessionBindingListener;
16 import javax.servlet.http.HttpSessionEvent;
17 import javax.servlet.http.HttpSessionListener;
18 
19 /**
20  * Application Lifecycle Listener implementation class logNum
21  *
22  */
23 @WebListener
24 public class logNum implements HttpSessionListener {
25     private int online=0;
26 
27     public void sessionCreated(HttpSessionEvent arg0)  { 
28         online++;
29         arg0.getSession().getServletContext().setAttribute("Online",new Integer(online));
30     }
31     
32     public void sessionDestroyed(HttpSessionEvent arg0)  { 
33         online--;
34         arg0.getSession().getServletContext().setAttribute("Online",new Integer(online));
35    }
36 }
logNum.java(监听器)
 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
 3   <display-name>Session</display-name>
 4   <welcome-file-list>
 5     <welcome-file>index.html</welcome-file>
 6     <welcome-file>index.htm</welcome-file>
 7     <welcome-file>index.jsp</welcome-file>
 8     <welcome-file>default.html</welcome-file>
 9     <welcome-file>default.htm</welcome-file>
10     <welcome-file>default.jsp</welcome-file>
11   </welcome-file-list>
12     <listener>
13         <listener-class>com.a.logNum</listener-class>
14     </listener>
15     <session-config>
16         <session-timeout>1</session-timeout>
17     </session-config>
18 </web-app>
web.xml

 

链接：https://pan.baidu.com/s/1_kfVWtfJqD2oEWpCcwx__w
提取码：yfr7
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posted @ 2019-04-10 15:38  Joker_zou  阅读(147)  评论(0)  编辑  收藏  举报