跨设备状态同步实战：基于 HarmonyOS 分布式数据管理（DDM）构建多端协同应用

// store/DistributedTodoStore.ets
import distributedData from '@ohos.data.distributedData';

class DistributedTodoStore {
  private kvManager: distributedData.KVManager | null = null;

  async init() {
    const config: distributedData.KVManagerConfig = {
      bundleName: 'com.example.todoapp',
      storeName: 'todo_items' // 同一 storeName 的设备会自动同步
    };
    this.kvManager = await distributedData.createKVManager(config);
    console.log('分布式存储初始化成功');
  }

  // 写入待办事项
  async putTodo(id: string, todo: TodoItem): Promise<void> {
    if (!this.kvManager) throw new Error('Store not initialized');
    await this.kvManager.put(id, JSON.stringify(todo));
  }

  // 读取单条
  async getTodo(id: string): Promise<TodoItem | null> {
    if (!this.kvManager) return null;
    const val = await this.kvManager.get(id);
    return val ? JSON.parse(val) : null;
  }

  // 获取所有（需遍历）
  async getAllTodos(): Promise<TodoItem[]> {
    if (!this.kvManager) return [];
    const result: TodoItem[] = [];
    await this.kvManager.on('dataChange', (device, key) => {
      // 注意：getAll 需结合快照或本地缓存，此处简化
    });
    // 实际建议：维护本地列表 + 监听增量更新
    return result;
  }
}

// pages/Index.ets
@Entry
@Component
struct TodoListPage {
  @State todos: TodoItem[] = [];
  private store = new DistributedTodoStore();

  aboutToAppear() {
    this.store.init();
    this.loadTodos();
    this.setupListener();
  }

  build() {
    Column() {
      Button('添加测试任务')
        .onClick(async () => {
          const newTodo: TodoItem = {
            id: Date.now().toString(),
            title: '来自手机的新任务',
            completed: false,
            createdAt: Date.now()
          };
          await this.store.putTodo(newTodo.id, newTodo);
          // 无需手动刷新 UI，监听器会触发更新
        })
      // 渲染列表...
    }
  }
}

// 在 aboutToAppear 中注册监听
private setupListener() {
  if (!this.store.kvManager) return;
  
  this.store.kvManager.on('dataChange', (device, key) => {
    // device: 变更来源设备 networkId
    // key: 变更的键（如 "1712345678901"）
    
    // 重新加载全部数据（简化版）
    this.loadTodos();
    
    // 更优做法：仅更新变更项
    // this.updateSingleTodo(key);
  });
}

private async toggleComplete(id: string) {
  const todo = await this.store.getTodo(id);
  if (todo) {
    todo.completed = !todo.completed;
    await this.store.putTodo(id, todo); // 写入即同步
  }
}

private async deleteTodo(id: string) {
  if (this.store.kvManager) {
    await this.store.kvManager.delete(id); // 删除也同步
  }
}

async safeUpdate(id: string, updater: (old: TodoItem) => TodoItem) {
  const current = await this.store.getTodo(id);
  const updated = updater(current || createDefault());
  await this.store.putTodo(id, updated);
}