cookie的使用

package servlet;

import javax.servlet.http.Cookie;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class MyServlet
 */
@WebServlet("/MyServlet")
public class MyServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public MyServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        // 判断是否拥有cookie
        Cookie[] cookies = request.getCookies();
        //String value = "";
        if (cookies != null) {
            for (int i=0;i<cookies.length;i++) {
                if (cookies[i].getName().equals("remember")) {
                    response.sendRedirect("After.html");
                    return;
                }
            }
        }
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String remember = request.getParameter("remember");
        // 判断账号密码是否正确，默认账号密码为：tom  123
        if (username != null && password != null) {
            if (!username.isEmpty() && !password.isEmpty() ) {
                if (username.equals("tom") && password.equals("123")&&remember!=null) {
                    Cookie newCookie = new Cookie("remember", "1");
                    newCookie.setMaxAge(30*24*60*60);
                    response.addCookie(newCookie);
                    response.sendRedirect("After.html");
                    return;
                } else if(username.equals("tom") && password.equals("123")){
                    response.sendRedirect("After.html");
                    return;
                }
            }
        }
        response.sendRedirect("Login.html");
    }
}