HarmonyOS开发实例：【分布式数据管理】

介绍

本示例展示了在eTS中分布式数据管理的使用，包括KVManager对象实例的创建和KVStore数据流转的使用。

通过设备管理接口[@ohos.distributedDeviceManager]，实现设备之间的kvStore对象的数据传输交互，该对象拥有以下能力 ;
1、注册和解除注册设备上下线变化监听
2、发现周边不可信设备
3、认证和取消认证设备
4、查询可信设备列表
5、查询本地设备信息，包括设备名称，设备类型和设备标识
6、发布设备发现

效果预览

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使用说明

鸿蒙OS开发	更多内容↓点击	HarmonyOS与OpenHarmony技术
鸿蒙技术文档	开发知识更新库gitee.com/li-shizhen-skin/harmony-os/blob/master/README.md在这。

1.两台设备组网。

2.在一台界面中点击右上角的流转按钮，在弹窗中选择对端设备拉起对端设备上的应用。

3.拉起对端设备后，在界面中点击"+"按钮新增笔记卡片，点击每个卡片右上角的"X"按钮可以删除此卡片，可以看到对端设备和当前设备界面数据保持一致。

4.操作对端设备，当前设备界面也会保持和对端设备界面显示一致。

具体实现

管理kvStore

1、页面初始化时获取此应用所需能力：引入@ohos.data.distributedKVStore初始化kvstore数据库并对使用kvstore.on数据change进行监听，通过appstorge判断获取相应的key判断是否是分布式节点 。

源码：

/** Copyright (c) 2020-2023 Huawei Device Co., Ltd.* Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at**     http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/import abilityAccessCtrl from '@ohos.abilityAccessCtrl'import common from '@ohos.app.ability.common'import { NoteModel } from '../model/NoteDataModel'import { NoteListItem } from '../common/NoteItem'import NoteDataSource from '../common/BasicDataSource'import { TitleBar } from '../common/TitleBar'import { KvStoreModel } from '../model/KvStoreModel'import { RemoteDeviceModel } from '../model/RemoteDeviceModel'import { transStrToNoteModel } from '../model/NoteDataModel'import Logger from '../util/Logger'import Want from '@ohos.app.ability.Want';const NOTES_CHANGE = 'notesChange'const EXIT = 'exit'let kvStoreModel: KvStoreModel = new KvStoreModel()let notesNum: number = 0const TAG = 'KvstoreIndexPage'@Entry@Componentstruct Index {private noteDataSource: NoteDataSource = new NoteDataSource([new NoteModel('', '')]);@State isDistributed: boolean = falseprivate remoteDeviceModel: RemoteDeviceModel = new RemoteDeviceModel()aboutToAppear() {let context = getContext(this) as common.UIAbilityContextlet atManager = abilityAccessCtrl.createAtManager()try {atManager.requestPermissionsFromUser(context,['ohos.permission.DISTRIBUTED_DATASYNC']).then((data) => {Logger.info(TAG, `data: ${JSON.stringify(data)}`)}).catch((err: object) => {Logger.info(TAG, `err: ${JSON.stringify(err)}`)})} catch (err) {Logger.info(TAG, `catch err->${JSON.stringify(err)}`);}let want = JSON.parse(AppStorage.Get('wantMsg')) as Want;Logger.info(TAG,`getWant =${JSON.stringify(want)}`);if(want.parameters != undefined) {if (want.parameters.isStage === 'Stage') {this.isDistributed = true}}kvStoreModel.setOnMessageReceivedListener(NOTES_CHANGE, (value) => {Logger.info(TAG,`NOTES_CHANGE${value}`)if (this.isDistributed) {if (value.search(EXIT) !== -1) {Logger.info(TAG,`[json]EXIT${EXIT}`)context.terminateSelf((error) => {Logger.info(TAG,`terminateSelf finished, error=${error}`)})} else {let str: string = value.substring(0, value.lastIndexOf('}]') + 2);this.noteDataSource.dataArray = transStrToNoteModel(str);this.noteDataSource.notifyDataReload()let strNum: string = value.substring(value.lastIndexOf('numBegin') + 'numBegin'.length, value.lastIndexOf('numEnd'));notesNum = Number(strNum)}}})}deleteNoteCallBack = (item: NoteModel) => {Logger.info(TAG, `deleteNote${JSON.stringify(item)}`);let dataArray: NoteModel[] = this.noteDataSource.dataArray;for (let i = 0; i < dataArray.length; i++) {Logger.info(TAG, `i = ${i} and dataArray = ${JSON.stringify(dataArray[i])}`)if (dataArray[i].title === item.title) {Logger.info(TAG, `deleteNote index` + i);this.noteDataSource.dataArray.splice(i, 1);break}}this.noteDataSource.notifyDataReload()kvStoreModel.put(NOTES_CHANGE, JSON.stringify(this.noteDataSource.dataArray) + 'numBegin' + notesNum + 'numEnd');}startAbilityCallBack = (key: string) => {Logger.info(TAG,`startAbilityCallBack${key}`);if (NOTES_CHANGE === key) {kvStoreModel.put(NOTES_CHANGE, `${JSON.stringify(this.noteDataSource.dataArray)}numBegin${notesNum}numEnd`);}if (EXIT === key) {kvStoreModel.put(NOTES_CHANGE, EXIT)}}build() {Column() {TitleBar({startAbilityCallBack: this.startAbilityCallBack,remoteDeviceModel: this.remoteDeviceModel,isDistributed: $isDistributed})Grid() {LazyForEach(this.noteDataSource, (item: NoteModel, index) => {GridItem() {NoteListItem({note: item,deleteNoteCallBack: this.deleteNoteCallBack,noteID: index})}.onClick(() => {Logger.info(TAG,`GridItem.click${item.title}`);if (item.title === '' && item.content === '') {notesNum += 1this.noteDataSource.dataArray[this.noteDataSource.dataArray.length-1] = new NoteModel(`note ${notesNum}`, 'noteContent');this.noteDataSource.dataArray.push(new NoteModel('', ''));this.noteDataSource.notifyDataReload()if (this.isDistributed) {kvStoreModel.put(NOTES_CHANGE, `${JSON.stringify(this.noteDataSource.dataArray)}numBegin${notesNum}numEnd`);}}})}, (item: NoteModel) => item.title)}.columnsTemplate('1fr 1fr 1fr').columnsGap(10).rowsGap(10).padding(10).margin({ bottom: 50 })}}onDestroy() {if (this.remoteDeviceModel !== null) {this.remoteDeviceModel.unregisterDeviceListCallback()}if (this.isDistributed) {this.isDistributed = false}}}

2、如果是分布式节点，如果数据发生变化，处理数据并使用.noteDataSource()进行reload数据。
3、页面通过kvStore对象进行增删改查会触发其他已连接设备的kvStore.on监听。

管理分布式设备（节点）

1、创建设备管理对象，并指定参数kvstore应用包deviceManager.createDeviceManager("ohos.samples.kvstore", (error, value) => {})
2、获取可信设备列表，"this.deviceManager.getTrustedDeviceListSync())" 。 3、监听设备状态，"this.deviceManager.on('deviceStateChange', (data) => {})"，从而对可信设备列表管理。

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