Session机制下的邮件系统小应用
一个mailLogin的jsp页面:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><html> <head> <title>My JSP 'mailLogin.jsp' starting page</title> </head> <body> <% String username=""; if(!session.isNew()){ username=(String)session.getAttribute("username"); if(null==username){ username=""; } } %> 当前session是否为新：<%=session.isNew()%><br> <form action="mailCheck.jsp"> username：<input type="text" name="username" value="<%=username %>"><br> <input type="submit" value="submit"> </form> </body></html>一个mailCheck的jsp页面：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><html> <head> <title>My JSP 'mailCheck.jsp' starting page</title> </head> <body> <% String username=request.getParameter("username"); session.setAttribute("username",username); %> 当前session是否为新：<%=session.isNew()%><br> <a href="mailLogin.jsp">返回登录</a><br> <a href="mailLogout.jsp">注销登录</a><br> <a href="mailLogout1.jsp">注销登录1</a><br> 当前用户为：<%=username%><br> <a>您共有1000封邮件未读</a><br> </body></html>一个mailLogout的jsp页面：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%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 'mailLogout.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> 当前session是否为新：<%=session.isNew()%><br> <% String name =(String )session.getAttribute("username"); session.invalidate(); %> <a><%=name %> 再见</a> <a href="mailLogin.jsp">重新登录</a> </body></html>为了与上面mailLogout对比，又另外写了一个无session.invalidate()的mailLogout1的jsp页面：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%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 'mailLogout1.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> 当前session是否为新：<%=session.isNew()%><br> <%String name=(String)session.getAttribute("username"); session.setAttribute("username",name); %> <a><%=name %>再见</a> <a href="mailLogin.jsp">返回登录</a> </body></html>运行效果为：
1运行mailLogin 页面显示如下：
2点击登录
3 分别点击注销登录
3.再点击返回登录
则此时session 已经从新重建了一个
4在点击登录
5此时点击注销登录1
6点击返回登录
观察结果是 此时session并没有新建一个 因为此时session并没有invalidate()