// 登录页 可直接 tomcat部署 测试 
 1 package com.itheima.login;

 import java.io.IOException;

 import java.io.PrintWriter;

 import javax.servlet.ServletException;

 import javax.servlet.http.Cookie;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 public class LoginServlet extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         response.setContentType("text/html;charset=UTF-8");

         PrintWriter out = response.getWriter();

         String userName ="";

         String checked = "";

         //得到客户端保存的Cookie数据

         Cookie[] cookies = request.getCookies();

         for (int i = 0;cookies!=null && i < cookies.length; i++) {

             if("userName".equals(cookies[i].getName())){

                 userName = cookies[i].getValue();

                 checked = "checked='checked'";

             }

         }

         out.write("<form action='"+request.getContextPath()+"/servlet/doLogin' method='post'>");

         out.write("用户名：<input type='text' name='userName' value='"+userName+"'/><br/>");

         out.write("密码：<input type='password' name='pwd'/><br/>");

         out.write("<input type='checkbox' name='remember' "+checked+" />记住用户名<br/>");

         out.write("<input type='submit' value='登录'/><br/>");

         out.write("</form>");

     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         doGet(request, response);

     }

 }

package com.itheima.login;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class DoLoginServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8");

        response.setContentType("text/html;charset=UTF-8");

        PrintWriter out = response.getWriter();

        //获取表单数据

        String userName = request.getParameter("userName");

        String pwd = request.getParameter("pwd");

        String remember = request.getParameter("remember");

        Cookie ck = new Cookie("userName", userName);

        ck.setPath("/");

        //处理业务逻辑

        //分发转向

        if("tom".equals(userName)&&"123".equals(pwd)){

            if(remember!=null){

                ck.setMaxAge(Integer.MAX_VALUE);//设置Cookie的有效保存时间

            }else{

                ck.setMaxAge(0);//删除 Cookie

            }

            response.addCookie(ck);//将Cookie写回到客户端

            out.write("登录成功！");

        }else{

            out.write("登录失败！");

            //设置2秒跳到重新登录

            response.setHeader("refresh", "2;url="+request.getContextPath()+"/servlet/login");

        }

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doGet(request, response);

    }

}