HarmonyOS 鸿蒙Next中，ArkTS如何定义Interface接口和Type类型？Record、泛型等如何使用？

在ArkTS中，定义清晰的接口和类型是构建健壮数据模型的基础。以下是针对你问题的具体实现：

1. 基础接口定义

// 定义基础接口
interface User {
  readonly id: number;      // 只读属性，初始化后不可修改
  name: string;
  age?: number;            // 可选属性
  email: string;
}

// 使用示例
const user: User = {
  id: 1,
  name: "张三",
  email: "zhangsan@example.com"
  // age 是可选的，可以不提供
};

2. 联合类型与字面量类型

// 字面量类型限定特定值
type Status = 'active' | 'inactive' | 'pending';
type UserRole = 'admin' | 'user' | 'guest';

// 联合类型组合多种类型
type ID = number | string;
type ResponseData = string | number | boolean | object;

interface Order {
  id: ID;
  status: Status;
  role: UserRole;
}

// 使用示例
const order: Order = {
  id: "ORD-001",  // 可以是字符串
  status: 'active', // 只能是三个值之一
  role: 'admin'
};

3. 泛型接口

// 定义泛型接口
interface ApiResponse<T> {
  code: number;
  message: string;
  data: T;
  timestamp: number;
}

// 定义分页数据泛型
interface PaginatedList<T> {
  items: T[];
  total: number;
  page: number;
  pageSize: number;
}

// 使用示例
interface Product {
  id: number;
  name: string;
  price: number;
}

const productResponse: ApiResponse<Product> = {
  code: 200,
  message: "成功",
  data: { id: 1, name: "手机", price: 2999 },
  timestamp: Date.now()
};

const productList: PaginatedList<Product> = {
  items: [
    { id: 1, name: "手机", price: 2999 },
    { id: 2, name: "平板", price: 1999 }
  ],
  total: 2,
  page: 1,
  pageSize: 10
};

4. Record类型

// 使用Record定义动态键的对象
type UserScores = Record<string, number>;

// 更严格的键约束
type StatusMap = Record<'pending' | 'processing' | 'completed', number>;

// 使用示例
const scores: UserScores = {
  'user1': 95,
  'user2': 87,
  'user3': 92
};

const statusCounts: StatusMap = {
  pending: 5,
  processing: 3,
  completed: 12
};

// 复杂的Record使用
interface ProductInfo {
  name: string;
  price: number;
}

type ProductCatalog = Record<string, ProductInfo>;

const catalog: ProductCatalog = {
  'p001': { name: '手机', price: 2999 },
  'p002': { name: '平板', price: 1999 }
};

5. 接口继承

// 基础接口
interface BaseEntity {
  readonly id: number;
  createdAt: string;
  updatedAt: string;
}

// 继承扩展
interface UserEntity extends BaseEntity {
  username: string;
  email: string;
  isActive: boolean;
}

// 多层继承
interface AdminUser extends UserEntity {
  permissions: string[];
  role: 'super_admin' | 'admin';
}

// 使用示例
const userEntity: UserEntity = {
  id: 1,
  createdAt: "2024-01-01",
  updatedAt: "2024-01-02",
  username: "admin",
  email: "admin@example.com",
  isActive: true
};

const adminUser: AdminUser = {
  ...userEntity,
  permissions: ['create', 'update', 'delete'],
  role: 'super_admin'
};

6. 完整数据模型示例

// 类型定义
type Gender = 'male' | 'female' | 'other';
type UserStatus = 'active' | 'inactive' | 'suspended';

// 基础接口
interface Timestamp {
  createdAt: string;
  updatedAt?: string;
  deletedAt?: string;
}

// 用户接口
interface User extends Timestamp {
  readonly id: number;
  username: string;
  email: string;
  age?: number;
  gender: Gender;
  status: UserStatus;
  metadata?: Record<string, any>;
}

// 泛型响应接口
interface ApiResponse<T = any> {
  success: boolean;
  data: T;
  error?: string;
  pagination?: {
    page: number;
    pageSize: number;
    total: number;
  };
}

// 使用示例
const userData: User = {
  id: 1,
  username: "john_doe",
  email: "john@example.com",
  gender: "male",
  status: "active",
  createdAt: "2024-01-01T00:00:00Z",
  metadata: {
    lastLogin: "2024-01-02T10:30:00Z",
    loginCount: 42
  }
};

const apiResponse: ApiResponse<User> = {
  success: true,
  data: userData
};

这些示例覆盖了ArkTS中类型定义的主要场景。关键点包括：使用interface定义对象结构，type定义类型别名，readonly确保属性不可变，?标记可选属性，泛型提供类型灵活性，Record处理动态键对象，extends实现类型继承。