鸿蒙系统-同应用跨设备数据同步（分布式功能）

一. 场景介绍

跨设备数据同步功能（即分布式功能），指将数据同步到一个组网环境中的其他设备。常用于用户应用程序数据内容在可信认证的不同设备间，进行自由同步、修改和查询。

二. 跨设备同步访问控制机制

在进行开发之前，先要了解一下跨设备同步访问控制机制，数据跨设备同步时，数据管理基于设备等级和数据安全标签进行访问控制，具体如下：

设备安全级别	可同步的数据安全标签
SL1	S1
SL2	S1~S2
SL3	S2~S3
SL4	S3~S4
SL5	S4~S5

手表通常为低安全的SL1设备。若创建数据安全标签为S1的数据库，则此数据库数据可以在这些设备间同步；若创建的数据库标签为S2-S4，则不能在这些设备间同步。
总结：想要开设备同步，设备安全级别需要设置为：S1
具体设置代码：

 const options: distributedKVStore.Options = {//设置安全等级securityLevel: distributedKVStore.SecurityLevel.S1};

三.键值型数据库跨设备数据同步

1. 导入模块

import { distributedKVStore } from '@kit.ArkData';

2. 申请权限

在module.json5中requestPermissions里面配置权限：

  {"name": "ohos.permission.DISTRIBUTED_DATASYNC","reason": "$string:write_permission","usedScene": {"abilities": ["EntryAbility"],"when": "always"}},

3. 创建kvManager对象

  let config: distributedKVStore.KVManagerConfig = {bundleName: context.abilityInfo.bundleName,context: context};try {this.kvManager = distributedKVStore.createKVManager(config);} catch (error) {PhLog.error(`createKvStore createKVManager failed, err=${JSON.stringify(error)}`, 'KvStoreViewModel');reject(`createKvStore createKVManager failed, err=${JSON.stringify(error)}`);return;}

4. 获取并得到指定类型的键值型数据库

    let options: distributedKVStore.Options = {createIfMissing: true,encrypt: false,backup: false,autoSync: true,//自动同步功能kvStoreType: distributedKVStore.KVStoreType.DEVICE_COLLABORATION,securityLevel: distributedKVStore.SecurityLevel.S1//设置安全等级};// this.kvManager.getKVStore(CommonConstants.KV_STORE_ID, options).then((store: distributedKVStore.SingleKVStore) => {this.kvManager.getKVStore(CommonConstants.KV_STORE_ID, options).then((store: distributedKVStore.DeviceKVStore) => {if (store === null) {PhLog.error(`createKvStore getKVStore store is null`, 'KvStoreViewModel');reject(`createKvStore getKVStore store is null`);return;}this.kvStore = store;this.kvStore.enableSync(true).then(() => {resolve(1);PhLog.info('createKvStore enableSync success', 'KvStoreViewModel');}).catch((error: Error) => {reject(`createKvStore enableSync fail, error=${JSON.stringify(error)}`);PhLog.error(`createKvStore enableSync fail, error=${JSON.stringify(error)}`, 'KvStoreViewModel');});this.setDataChangeListener(() => {});}).catch((error: Error) => {reject(`createKvStore getKVStore failed, error=${JSON.stringify(error)}`);PhLog.error(`createKvStore getKVStore failed, error=${JSON.stringify(error)}`, 'KvStoreViewModel');})

5. 订阅、移除分布式数据变化

	try {//订阅kvStore.on('dataChange', distributedKVStore.SubscribeType.SUBSCRIBE_TYPE_ALL, (data) => {console.info(`dataChange callback call data: ${data}`);});} catch (e) {let error = e as BusinessError;console.error(`An unexpected error occurred. code:${error.code},message:${error.message}`);}try {//移除订阅数据变化this.kvStore.off('dataChange');} catch (error) {PhLog.error(`removeDataChangeListener off('dataChange') failed, err=${JSON.stringify(error)}`, 'KvStoreViewModel');}

6. 将数据写入分布式数据库。

 put(key: string, value: string): void {if (this.kvStore === undefined) {return;}this.kvStore.put(key, value).then(() => {PhLog.info(`kvStore.put key=${key} finished}`, 'KvStoreViewModel');}).catch((error: Error) => {PhLog.error(`kvStore.put key=${key} failed, error=${JSON.stringify(error)}`, 'KvStoreViewModel');});}

7. 查询数据

 async get(key: string): Promise<boolean | string | number | Uint8Array> {return new Promise((resolve, reject) => {if (this.kvStore === undefined) {PhLog.info('失败了')reject();return;}this.kvStore.get(key).then((res) => {resolve(res)PhLog.info(`kvStore.put key=${key} finished}`, 'KvStoreViewModel');}).catch((error: Error) => {resolve('')PhLog.error(`kvStore.put key=${key} failed, error=${JSON.stringify(error)}`, 'KvStoreViewModel');});})}

8. 同步数据到其他设备

try {// 1000表示最大延迟时间为1000mskvStore.sync(deviceIds, distributedKVStore.SyncMode.PUSH_ONLY, 1000);} catch (e) {let error = e as BusinessError;console.error(`An unexpected error occurred. Code:${error.code},message:${error.message}`);}```

9.删除数据

  async delete(key: string): Promise<void> {return new Promise((resolve, reject) => {if (this.kvStore === undefined) {PhLog.info('失败了')reject();return;}this.kvStore.delete(key).then( ()=> {resolve();})})}```