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

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
双端设备均安装此应用
滑动浏览手机端视频，打开平板端应用
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

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

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 Data
 let 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 Exit
 wantParam["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 data
 if (launchParam.launchReason === AbilityConstant.LaunchReason.CONTINUATION) {
   // Restore migrated data from want
   let activeLive = want?.parameters?.activeLive;
   AppStorage.setOrCreate<number>('activeLive', activeLive as number);
   Logger.info(activeLive as string);
   // Explicit invocation of page restore
   this.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 data
 if (launchParam.launchReason === AbilityConstant.LaunchReason.CONTINUATION) {
   // Restore migrated data from want
   let activeLive = want?.parameters?.activeLive;
   AppStorage.setOrCreate<number>('activeLive', activeLive as number);
   Logger.info(activeLive as string);
   // Explicit invocation of page restore
   this.contentStorage = new LocalStorage();
   Logger.info('Ability onNewWant restoreWindowStage');
   this.context.restoreWindowStage(this.contentStorage);
 }

}

// Check permission granting and dynamically apply for permissions
async checkPermissions(): Promise<void> {
const permissions: Array<Permissions> = ['ohos.permission.DISTRIBUTED_DATASYNC'];

 let grantStatus: abilityAccessCtrl.GrantStatus = await this.checkAccessToken(permissions[0]);
 // Verifying Permission Granting
 if (grantStatus === abilityAccessCtrl.GrantStatus.PERMISSION_GRANTED) {
   // Granted
   Logger.info('Permission already granted.');
 } else {
   // Not granted. Dynamically apply for authorization in the dialog box displayed to the user
   let 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 permissions
async checkAccessToken(permission: Permissions): Promise<abilityAccessCtrl.GrantStatus> {
let atManager = abilityAccessCtrl.createAtManager();
let grantStatus: abilityAccessCtrl.GrantStatus = -1;

 // Obtains the token ID
 let 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 ability
Logger.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 resources
Logger.info('Ability onWindowStageDestroy');
}

onWindowStageRestore(windowStage: window.WindowStage): void {
WindowUtil.requestFullScreen(windowStage, this.context);
}

onForeground(): void {
// Ability has brought to foreground
Logger.info('Ability onForeground');
}

onBackground(): void {
// Ability has back to background
Logger.info('Ability onBackground');
}
}

获取目标设备的设备ID。
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。
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。
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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