//login.jsp
<%@ page language="java" pageEncoding="UTF-8"%>
<html>
<head>
<title>用户登录</title>
</head>
<body>
<form method="post" action="logincheck.jsp">
用户名：<input type="text" size="10"name="username"><br/>
密 码：<input type="password" name="userpwd"/><br/>
<input type="submit" value="登录">
</form>
</body>
</html>
//logincheck.jsp
<%@ page pageEncoding="UTF-8"%>
<html>
<head>
<title>登录处理</title>
</head>
<body>
<%
String un=request.getParameter("username");
if(un!=null)
{
Cookie c=new Cookie("username",un);
c.setMaxAge(30*24*3600);
response.addCookie(c);
session.setAttribute("username",un);
response.sendRedirect("main.jsp");
}
%>
</body>
</html>
<%@ page pageEncoding="UTF-8"%>
<html>
<head>
<title>主页面</title>
</head>
<body>
<%
String username=(String)session.getAttribute("username");
if(username==null)
{
Cookie[] cs=request.getCookies();
String v=null;
if(cs!=null)
{
for(int i=0;i<cs.length;i++)
{
if(cs[i].getName().equals("username"))
{
v=cs[i].getValue();
}
}
}
if(v!=null)
{
session.setAttribute("username", v);
out.println(v+"，您好");
}
else
{
out.println("您还没注册，2秒后转到注册页面");
response.setHeader("Refresh","2;url=login.jsp");
}
}
else
{out.print(username+"，您好");
}%>
</body>
</html>