需求：

1、登录账号唯一，在注册时验证输入的账号是否可用，若已存在，则不可用，若不存在则可用 

2、登录时使用账号密码进行验证 

 

 1 package login;
 2 
 3 public class Login {
 4     private String accounts;//登录账户
 5     private String password;//登录密码
 6     private String phone;//手机号
 7     public String getPhone() {
 8         return phone;
 9     }
10     public void setPhone(String phone) {
11         this.phone = phone;
12     }
13     public String getAccounts() {
14         return accounts;
15     }
16     public void setAccounts(String accounts) {
17         this.accounts = accounts;
18     }
19     public String getPassword() {
20         return password;
21     }
22     public void setPassword(String password) {
23         this.password = password;
24     }
25     
26     public Login() {
27         // TODO Auto-generated constructor stub
28     
29     }
30     public Login(String accounts, String password, String phone) {
31         super();
32         this.accounts = accounts;
33         this.password = password;
34         this.phone = phone;
35     }
36     
37 }

 

 1 package login;
 2 
 3 import java.util.HashMap;
 4 import java.util.Scanner;
 5 import java.util.Set;
 6 
 7 import com.student.Student;
 8 
 9 public class LoginSystem {
10     static Scanner sc = new Scanner(System.in);
11 
12     public static void main(String[] args) {
13         // 初始化信息
14         Login user1 = new Login("asd00000", "123456", "13900000000");
15         Login user2 = new Login("qwe00000", "234567", "15900000000");
16         Login user3 = new Login("zxc00000", "345678", "13800000000");
17 
18         HashMap<String, Login> map = new HashMap<>();
19         map.put(user1.getAccounts(), user1);
20         map.put(user2.getAccounts(), user2);
21         map.put(user3.getAccounts(), user3);
22 
23         System.out.println("***欢迎进入系统大厅***");
24         System.out.println("请选择：1、登录 2、注册、3、退出系统");
25         String change = sc.next();
26         switch (change) {
27         case "1":
28             System.out.print("请输入登录账户：");
29             String account = sc.next();
30             System.out.print("请输入登录密码：");
31             String password = sc.next();
32             // 判断验证登录信息（核查账户与密码匹配）
33             if (map.containsKey(account) && map.get(account).getPassword().equals(password)) {
34                 System.out.println("登录成功！!正在加载系统...");
35             } else if (map.containsKey(account) && !map.get(account).getPassword().equals(password)) {
36                 System.out.println("密码错误！已退出登录！");
37             } else {
38                 System.out.println("输入账户不正确！登录失败！");
39             }
40             break;
41         case "2":
42             System.out.println("请输入注册账户：");
43             String addAccount = sc.next();
44             if (map.containsKey(addAccount)) {
45                 System.out.println("账户已存在，注册失败！");
46                 break;
47             } else {
48                 System.out.println("请输入注册密码：");
49                 String addPassword = sc.next();
50                 System.out.println("请输入手机号码：");
51                 String addPhone = sc.next();
52                 System.out.println("注册成功！");
53                 System.out.println("您的登录账户为：" + addAccount + "，登录密码为：" + addPassword + ",预留手机号为：" + addPhone);
54             }
55             break;
56         default:
57             System.out.println("成功退出登录系统！");
58         }
59     }
60 
61 }