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 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');
  }
}

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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