注册登录，基本操作满足，部分知识还需补习

package cn.limitinglogin;
//会员类
public class Users {
        private String name;
        private String password;
        public Users() {}
        public Users(String name, String password) {
            super();
            this.name = name;
            this.password = password;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getPassword() {
            return password;
        }
        public void setPassword(String password) {
            this.password = password;
        }
        
    
}

package cn.limitinglogin;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

//后台模块类
public class Background {
        //储存会员信息
        static Scanner sc = new Scanner(System.in);
         
        static Map<String,Users>map = new HashMap<>();
        static long time1  = 0;//输错3次密码时的时间
        static long time2  = 0;//输入密码时间
        static int num;//密码输入错误的次数
        static final long time = 20;//账号不能登录的时间
        //会员注册部分
        public static void Loginz() {
            System.out.println("请输入用户昵称：");
            String name = sc.next();
            for(;name.length()<3;name = sc.next()) {             //p50
                System.out.println("用户名长度不能小于三位，请重新输入：");
            }
            System.out.println("请输入注册密码：");
            String password = sc.next();
            for(;password.length()<6;password = sc.next()) {
                System.out.println("密码长度小于6位，请重新输入：");
            }
            System.out.println("请再一次输入密码：");
            String password1 = sc.next();
            while(!password1.equals(password)) {
                System.out.println("两次密码不相同，请重新输入：");
                password1 = sc.next();
            }
            System.out.println("注册成功");
            //将会员信息存进去
            map.put(name, new Users(name,password));
        }
        //会员登录部分
        public static void Logind() {
            time2 = new Date().getTime();
            if(num < 3) {
                if(flag()) {
                    System.out.println("登入成功");
                }else {
                    num++;
                    System.out.println("密码输入错误，您当前已经输错"+num+"次，输错3次将暂时不能登录");//??
                    //记录此时的时间
                    if(num==3) {
                        time1 = new Date().getTime();
                    }
                }
            }else if((time1-time2)/1000>time) {//??
                //到达时间后3次被清除
                num = 0;
                if(flag()) {
                    System.out.println("登陆成功");
                }else {
                    num++;
                    System.out.println("密码输入错误，您当前已经输错"+num+"次，输错3次将暂时不能登录");
                }
            }else {
                System.out.println("您已经输错3次，请"+(time - (time2 - time1) / 1000)+"秒后重试");
            }
//            System.out.println("您已经输错3次请在");
            
        }
        //判断输入是否正确
        public static boolean flag() {
            System.out.println("请输入昵称：");
            String name = sc.next();
            System.out.println("请输入密码：");
            String password = sc.next();
            if(map.get(name)!=null) {
                if(name.equals(map.get(name).getName())&&password.equals(map.get(name).getPassword())) {
                    return true;
                }
                else {
                    return false;
                }
            }else {
                return false;
            }
            
        }
        
}

package cn.limitinglogin;

import java.util.Scanner;

//测试类
public class Test {
    static Scanner sc = new Scanner(System.in);
        public static void main(String[] args) {
            Background bg = new Background ();
             String xx = "";
             System.out.print("1、注册"+"\t"+"2、登录"+"\t"+"请输入你的选择：");
             xx = sc.next();
             for(;xx.equals("1")||xx.equals("2");xx = sc.next()) {
                 switch(xx) {
                 case "1":
                     bg.Loginz();//?怎么别人可以之间.出来
                     break;
                 case "2":
                     bg.Logind();
                     break;
                 }
                 System.out.print("1、注册"+"\t"+"2、登录"+"\t"+"请输入你的选择：");
             }
        }
}