关于cookie的使用，实现30天免登陆，也就是记住密码的功能

这是登录之后，网页内cookie的相关信息

 

其次就是，在用户第一次登录时，如果选择了勾选自动登录按钮，cookie就会保存用户的信息，当用户再次登录时，就可以不用输入密码，自动登录了。

 

代码的相关实现

myServlet.java

package com.my.deal;import java.io.IOException;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;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;/** * 登录界面 */@WebServlet("/MyServlet")public class MyServlet extends HttpServlet {    /**     *      */    private static final long serialVersionUID = 1L;    private String driverName="com.mysql.jdbc.Driver";    private String url="jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";    private String name="root";    private String pwd="123456";    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        doPost(request, response);            }    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        String username = request.getParameter("username");        String password = request.getParameter("password");        String flag = request.getParameter("isLogin");        //设置页面编码格式        response.setContentType("text/html;charset=UTF-8");        String sql="select * from users where name='"+username+"' and password='"+password+"'";                System.out.println(sql);        Connection connection=null;        Statement statement=null;        ResultSet resultSet=null;        try {            Class.forName(driverName);//加载驱动            connection = DriverManager.getConnection(url, name, pwd);//获取连接            statement = connection.createStatement();            resultSet = statement.executeQuery(sql);            System.out.println(statement.toString());                        //查找以前登录过得信息            Cookie[] cookie=request.getCookies();            if(cookie!=null){                for(int i=0;i
      ");                response.getWriter().write("你的密码为："+password);                }            }            else {                response.getWriter().write("用户名或者密码错误");            }        } catch (ClassNotFoundException | SQLException e) {            e.printStackTrace();        }        try {            resultSet.close();            statement.close();            connection.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

 

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