JSP的session处理利用JSP内置的session对象的isNew方法判断当前session是否是第一次创建的。使

利用JSP内置的session对象的isNew方法判断当前session是否是第一次创建的。使用session.setAttribute来设置属性。

<%@ page import="java.io.*,java.util.*" %>
<%    

Date createTime = new Date(session.getCreationTime());    
Date lastAccessTime = new Date(session.getLastAccessedTime());     

String title = "Welcome Back to my website";    

Integer visitCount = new Integer(0);    
String visitCountKey = new String("visitCount");    
String userIDKey = new String("userID");    
String userID = new String("ABCD"); 
if (session.isNew()){       
	title = "Welcome to my website";       
	session.setAttribute(userIDKey, userID);       
	session.setAttribute(visitCountKey,  visitCount);    
}     

visitCount = (Integer)session.getAttribute(visitCountKey);    
visitCount = visitCount + 1;    
userID = (String)session.getAttribute(userIDKey);    
session.setAttribute(visitCountKey,  visitCount); %>

<html>
<head>
<title>Session Tracking</title>
</head>
<body>
<center>
<h1>Session Tracking</h1>
</center>
<table border="1" align="center"> 
<tr bgcolor="#949494">
   <th>Session info</th>
   <th>Value</th>
</tr> 
<tr>
   <td>id</td>
   <td><% out.print( session.getId()); %></td>
</tr> 
<tr>
   <td>Creation Time</td>
   <td><% out.print(createTime); %></td>
</tr> 
<tr>
   <td>Time of Last Access</td>
   <td><% out.print(lastAccessTime); %></td>
</tr> 
<tr>
   <td>User ID</td>
   <td><% out.print(userID); %></td>
</tr> 
<tr>
   <td>Number of visits</td>
   <td><% out.print(visitCount); %></td>
</tr> 
</table> 
</body>
</html>

第一次打开该JSP, 看到如下页面：

刷新页面，观察到Number of visits的计数器刷新，并且Time of Last Access的值为最后刷新时间：

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