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>