hTTP协议是无状态的，即信息无法通过HTTP协议本身进传递。为了跟踪用户的操作状态，ASP应用SESSION对象。JSP使用一个叫HttpSession的对象实现同样的功能。

    

  

输入http://localhost:8081/httpjstObject/session.jsp?user=admin
 <%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
 <html>
   <head>
     <title>session对象实例</title>
   <body>
     <H2>session对象实例</H2>
     <hr>
  <%
   String[] users = {"admin","liubin","dywdyw"};
   String user = null;
   String logined = null;
   Date createTime,lastAccessTime;
   if (request.getParameter("user")!=null){
    user = request.getParameter("user");
   }else{
    out.println("对不起，请在请求参数中附加用户帐号!");
    return;
   }
   for (int i=0;i<users.length;i++){
    if (users[i].equalsIgnoreCase(user)){
     session.setAttribute("logined","yes");
    }
   }
   if (session.getAttribute("logined")!= null){
    logined = session.getAttribute("logined").toString();
    if (logined.equals("yes")){     session.setMaxInactiveInterval(100);//设置session超时时间
     createTime = new Date(session.getCreationTime());
     lastAccessTime = new Date(session.getLastAccessedTime());
     out.println("恭喜您登录成功!<br>");
     out.println("您的SessionID为："+session.getId()+"<br>");
     out.println("创建时间为："+createTime+"<br>");
     out.println("最后的访问时间为："+lastAccessTime+"<br>");
     out.println("最大不活动时间间隔为："+session.getMaxInactiveInterval()+"秒<br>");
    }
    else{
     out.println("对不起，您的帐号无效!");
    }
   }else{
    out.println("对不起，您的帐号无效!");
   }
  %>
   </body>
 </html>