diff --git a/src/chapter4/demo49/Main.java b/src/chapter4/demo49/Main.java new file mode 100644 index 0000000..0df6ef6 --- /dev/null +++ b/src/chapter4/demo49/Main.java @@ -0,0 +1,90 @@ +package chapter4.demo49; + +import java.util.Scanner; + +public class Main { + // 处理用户的输入 + private static Scanner scanner = new Scanner(System.in); + // 用户管理器 + private static UserManager userManager = UserManager.getInstance(); + // 当前登录用户 + private static AbstractUser currentUser = null; + + public static void main(String[] args) { + while (true) { + printMainMenu(); + + try { + int choice = scanner.nextInt(); + switch (choice) { + case 1: + login(); + break; + case 2: + register(); + break; + case 3: + if (currentUser instanceof AdminUser) { + userManager.showAllUsers(); + } else { + System.out.println("权限不足！"); + } + break; + case 4: + if (currentUser instanceof AdminUser) { + System.out.print("请输入要删除的用户名："); + String username = scanner.next(); + userManager.removeUser(username); + System.out.println("删除用户成功！"); + } else { + System.out.println("权限不足！"); + } + break; + case 0: + System.out.println("谢谢使用，再见！"); + System.exit(0); + default: + System.out.println("无效的选择！"); + } + } catch (Exception e) { + System.out.println("发生错误：" + e.getMessage()); + scanner.nextLine(); // 清除输入缓冲 + } + } + } + + private static void printMainMenu() { + System.out.println("\n=====用户管理系统====="); + System.out.println("1. 用户登录"); + System.out.println("2. 用户注册"); + System.out.println("3. 查看用户列表（需管理员权限）"); + System.out.println("4. 删除用户（需管理员权限）"); + System.out.println("0. 退出系统"); + System.out.println("请选择功能："); + } + + private static void login() throws UserException { + System.out.print("请输入用户名："); + String username = scanner.next(); + System.out.print("请输入密码："); + String password = scanner.next(); + + currentUser = userManager.login(username, password); + System.out.println("登录成功！欢迎 " + currentUser.getUsername()); + + if (currentUser instanceof AdminUser) { + System.out.println("您以管理员身份登录"); + } + } + + private static void register() throws UserException { + System.out.print("请输入用户名："); + String username = scanner.next(); + System.out.print("请输入密码："); + String password = scanner.next(); + + NormalUser newUser = new NormalUser(username, password); + userManager.addUser(newUser); + System.out.println("注册成功！"); + } +} diff --git a/src/chapter4/demo49/User.java b/src/chapter4/demo49/User.java new file mode 100644 index 0000000..edeba15 --- /dev/null +++ b/src/chapter4/demo49/User.java @@ -0,0 +1,73 @@ +package chapter4.demo49; + +// 自定义异常类 +class UserException extends Exception { + public UserException(String message) { + super(message); + } +} + +// 用户操作接口 +interface UserOperation { + void changePassword(String newPassword) throws UserException; + void showInfo(); +} + +// 抽象用户类 +abstract class AbstractUser implements UserOperation { + protected String username; // 用户名 + protected String password; // 密码 + protected String userType; // 用户类型 + + // 构造方法 + public AbstractUser(String username, String password) { + this.username = username; + this.password = password; + } + + public String getUsername() { + return username; + } + + // 检查密码是否正确 + public boolean checkPassword(String password) { + return this.password.equals(password); + } + + @Override + public void showInfo() { + System.out.println("用户名：" + username + "，用户类型：" + userType); + } +} + +// 普通用户类 +class NormalUser extends AbstractUser { + public NormalUser(String username, String password) { + super(username, password); + this.userType = "普通用户"; + } + + @Override + public void changePassword(String newPassword) throws UserException { + if (newPassword.length() < 6) { + throw new UserException("密码长度不能小于6位"); + } + this.password = newPassword; + } +} + +// 管理员类 +class AdminUser extends AbstractUser { + public AdminUser(String username, String password) { + super(username, password); + this.userType = "管理员"; + } + + @Override + public void changePassword(String newPassword) throws UserException { + if (newPassword.length() < 8) { + throw new UserException("管理员密码长度不能小于8位"); + } + this.password = newPassword; + } +} diff --git a/src/chapter4/demo49/UserManager.java b/src/chapter4/demo49/UserManager.java new file mode 100644 index 0000000..000456d --- /dev/null +++ b/src/chapter4/demo49/UserManager.java @@ -0,0 +1,54 @@ +package chapter4.demo49; + +import java.util.HashMap; +import java.util.Map; + +class UserManager { + // 保证单例模式 + private static UserManager instance; + // 存储所有用户 + private Map users; + + private UserManager() { + users = new HashMap<>(); + // 初始化一个管理员账号 + users.put("admin", new AdminUser("admin", "admin123")); + } + + // 单例模式 + public static UserManager getInstance() { + if (instance == null) { + instance = new UserManager(); + } + return instance; + } + + public void addUser(AbstractUser user) throws UserException { + if (users.containsKey(user.getUsername())) { + throw new UserException("用户名已存在！"); + } + users.put(user.getUsername(), user); + } + + public AbstractUser login(String username, String password) throws UserException { + AbstractUser user = users.get(username); + if (user == null) { + throw new UserException("用户不存在！"); + } + if (!user.checkPassword(password)) { + throw new UserException("用户名或密码错误！"); + } + return user; + } + + public void removeUser(String username) { + users.remove(username); + } + + public void showAllUsers() { + System.out.println("当前系统用户列表："); + for (AbstractUser user : users.values()) { + user.showInfo(); + } + } +}