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: