鸿蒙系统开发【应用接续】基本功能

应用接续

介绍

基于ArkTS扩展的声明式开发范式编程语言编写的一个分布式视频播放器，主要包括一个直播视频播放界面，实现视频播放时可以从一台设备迁移到另一台设备继续运行，来选择更合适的设备继续执行播放功能以及PAD视频播放时协同调用手机编辑发送弹幕功能。

效果预览

使用说明

1. 准备手机端与平板端两台设备，并且登录同一华为账号，双端设备打开WI-FI和蓝牙，建议双端设备接入同一个局域网，可提升数据传输的速度
2. 双端设备均安装此应用
3. 滑动浏览手机端视频，打开平板端应用
4. 点击平板端手机输入按钮，调起手机端输入内容，提交后平板端查看

具体实现

1. 在实现协同接口前，应用需要申请协同所需的访问控制权ohos.permission.DISTRIBUTED_DATASYNC。 在requestPermissions字段中增加权限声明ohos.permission.DISTRIBUTED_DATASYNC
2. 同时需要在应用首次启动时弹窗向用户申请授权，在用户手动允许授权后，应用才会真正获取相应权限，从而成功访问操作目标对象。 在EntryAbility类中实现以下函数，从而在调用时动态弹窗向用户申请权限。

/** Copyright (c) 2024 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, AbilityConstant, bundleManager, Permissions, UIAbility, Want } from '@kit.AbilityKit';
import { window } from '@kit.ArkUI';
import { WindowUtil } from '../utils/WindowUtil';
import Logger from '../utils/Logger';export default class EntryAbility extends UIAbility {contentStorage?: LocalStorage;onContinue(wantParam: Record<string, Object>) {Logger.info(wantParam.version.toString(), wantParam.targetDevice.toString());// Preparing to Migrate Datalet activeLive: number = AppStorage.get<number>('activeLive') as number;// Save the data to be migrated in the 'data' field of wantParam.wantParam['activeLive'] = activeLive;// Setting the Source End Not to ExitwantParam["ohos.extra.param.key.supportContinueSourceExit"] = false;Logger.info(activeLive.toString());return AbilityConstant.OnContinueResult.AGREE}onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {Logger.info('Ability onCreate');this.checkPermissions();// If the invoking reason is migration, set the status to migratable to cope with cold start (ensuring migration continuity)if (launchParam.launchReason === AbilityConstant.LaunchReason.CONTINUATION) {this.context.setMissionContinueState(AbilityConstant.ContinueState.ACTIVE, (result) => {Logger.info(JSON.stringify(result));});}// Cold start of the application: Restore the saved migration dataif (launchParam.launchReason === AbilityConstant.LaunchReason.CONTINUATION) {// Restore migrated data from wantlet activeLive = want?.parameters?.activeLive;AppStorage.setOrCreate<number>('activeLive', activeLive as number);Logger.info(activeLive as string);// Explicit invocation of page restorethis.contentStorage = new LocalStorage();Logger.info('Ability onCreate restoreWindowStage');this.context.restoreWindowStage(this.contentStorage);}}onNewWant(want: Want, launchParam: AbilityConstant.LaunchParam) {Logger.info('Ability onCreate');// If the invoking reason is migration, set the status to migratable to cope with hot start (ensuring migration continuity)if (launchParam.launchReason === AbilityConstant.LaunchReason.CONTINUATION) {this.context.setMissionContinueState(AbilityConstant.ContinueState.ACTIVE, (result) => {Logger.info(JSON.stringify(result));});}//During the warm start of an application: Restore the saved migration dataif (launchParam.launchReason === AbilityConstant.LaunchReason.CONTINUATION) {// Restore migrated data from wantlet activeLive = want?.parameters?.activeLive;AppStorage.setOrCreate<number>('activeLive', activeLive as number);Logger.info(activeLive as string);// Explicit invocation of page restorethis.contentStorage = new LocalStorage();Logger.info('Ability onNewWant restoreWindowStage');this.context.restoreWindowStage(this.contentStorage);}}// Check permission granting and dynamically apply for permissionsasync checkPermissions(): Promise<void> {const permissions: Array<Permissions> = ['ohos.permission.DISTRIBUTED_DATASYNC'];let grantStatus: abilityAccessCtrl.GrantStatus = await this.checkAccessToken(permissions[0]);// Verifying Permission Grantingif (grantStatus === abilityAccessCtrl.GrantStatus.PERMISSION_GRANTED) {// GrantedLogger.info('Permission already granted.');} else {// Not granted. Dynamically apply for authorization in the dialog box displayed to the userlet atManager = abilityAccessCtrl.createAtManager();try {atManager.requestPermissionsFromUser(this.context, ['ohos.permission.DISTRIBUTED_DATASYNC'], (err, data) => {Logger.info(JSON.stringify(data));});} catch (err) {Logger.error(JSON.stringify(err));return;}}}// Get the grant status of the current app's permissionsasync checkAccessToken(permission: Permissions): Promise<abilityAccessCtrl.GrantStatus> {let atManager = abilityAccessCtrl.createAtManager();let grantStatus: abilityAccessCtrl.GrantStatus = -1;// Obtains the token IDlet tokenId: number = 0;try {let bundleInfo: bundleManager.BundleInfo =await bundleManager.getBundleInfoForSelf(bundleManager.BundleFlag.GET_BUNDLE_INFO_WITH_APPLICATION);let appInfo: bundleManager.ApplicationInfo = bundleInfo.appInfo;tokenId = appInfo.accessTokenId;} catch (err) {Logger.error(JSON.stringify(err));}try {grantStatus = await atManager.checkAccessToken(tokenId, permission);} catch (err) {Logger.error(JSON.stringify(err));}return grantStatus;}onDestroy(): void {Logger.info('Ability onDestroy');}onWindowStageCreate(windowStage: window.WindowStage): void {// Main window is created, set main page for this abilityLogger.info('Ability onWindowStageCreate');WindowUtil.requestFullScreen(windowStage, this.context);WindowUtil.updateStatusBarColor(this.context, true);windowStage.loadContent('pages/LivePage', (err) => {if (err.code) {Logger.error(JSON.stringify(err) ?? '');return;}Logger.info('Succeeded in loading the content.');});}onWindowStageDestroy(): void {// Main window is destroyed, release UI related resourcesLogger.info('Ability onWindowStageDestroy');}onWindowStageRestore(windowStage: window.WindowStage): void {WindowUtil.requestFullScreen(windowStage, this.context);}onForeground(): void {// Ability has brought to foregroundLogger.info('Ability onForeground');}onBackground(): void {// Ability has back to backgroundLogger.info('Ability onBackground');}
}

6. 获取目标设备的设备ID。
7. 在发起端设置目标组件参数，调用startAbilityForResult()接口启动目标端UIAbility，异步回调中的data用于接收目标端UIAbility停止自身后返回给调用方UIAbility的信息。
8. 在目标端UIAbility任务完成后，调用terminateSelfWithResult()方法，将数据返回给发起端的UIAbility。
9. 发起端UIAbility接收到目标端UIAbility返回的信息，对其进行处理。

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