用户管理高级版

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<String, AbstractUser> 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();
+        }
+    }
+}