使得Cookie简化用户登陆，要求如下：
1、用户第一次登陆时需要输入用户名和密码
2、当登陆成功后，在Cookie中保存用户的登陆信息
3、设置Cookie有效期为5分钟
4、在有效期内用户再次登陆时，直接显示用户名
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>login</title> </head>
<body> <%
Cookie cookie[] = request.getCookies();
String name ="";
if(cookie!=null){ for(int i=0;i<cookie.length;i++){
if(cookie[i].getName().equals("username")){
name = cookie[i].getValue(); }
}
} %> <form action="checklogin.jsp" method="post">
<table>
<tr>
<td>用户名：</td>
<td><input type="text" id="username" name="username" value="<%=name %>" /></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="text" name="password" /></td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="登陆" /></td>
</tr> </table> </form> </body>
</html>
checklogin.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>login</title>
</head>
<body>
<%
String username = request.getParameter("username");
String pwd = request.getParameter("password");
Cookie cookie = new Cookie("username",username);
//jsp要把封装好的cookie传递给客户端
response.addCookie(cookie);
cookie.setMaxAge(180000); %>
</body>
</html>