如何播放音频，当我的Flutter应用终止时（警报应用程序）

Question

我正在使用flutter创建的警报应用程序。我正在使用android_alarm_manager_plus，flutter_foreground_task，flutter_local_notifications作为实现警报核心功能的主要软件包。我基本上正在构建警报应用程序，以在特定时间触发选定的日子触发警报。

当应用在前景中还活着时，该应用程序可以通过显示通知并播放警报声来发射警报。但是，当我终止我的应用程序时，设置了警报；它将显示通知。但是没有播放警报。

我是我的PubSpec.yaml包

输入图像描述在此处（单击此链接以查看图像）

当警报发出时，执行了“ AlarmCallback”。在其中，我试图启动循环播放音频的前景服务。每当用户点击“停止警报”通知按钮时，我都会停止音频并关闭前景服务。 我试图向Google搜索这个问题，那里没有太大帮助。因此，请帮助我解决此问题。 这是“ AlarmCallback”，“ ForegroundService”和“ ForegroundServiceHandler”的代码。

alarmcallback

＆

foregroundStartServiceCallback

代码（顶级功能）

@pragma('vm:entry-point')
void startForegroundTaskCallback() {
  FlutterForegroundTask.setTaskHandler(ForegroundServiceHandler());
}

@pragma('vm:entry-point')
void alarmCallback(int id, Map<String, dynamic> params) async {
  debugPrint("The alarm callback is running !");
  bool isRunningService = await FlutterForegroundTask.isRunningService;

  debugPrint("The foreground service is running : $isRunningService");

  if (!isRunningService) {
    debugPrint("Init foreground task");
    ForegroundTaskService.init();
  } else {
    debugPrint("restart foreground task");
    await FlutterForegroundTask.restartService();
  }

  try {
    var map = params['params'] as Map<String, dynamic>;
    var alarmModel = Alarmsmodel.fromMap(map);

    debugPrint(alarmModel.toString());

    assert(alarmModel.audioPath != null,
        " Cannot play audio because ,audio path is null !");

    
    ForegroundTaskService.saveData("audioPath", alarmModel.audioPath);
    ServiceRequestResult serviceResult =
        await ForegroundTaskService.startService();

    if (serviceResult is ServiceRequestSuccess) {
      debugPrint("service result is success !");
    } else if (serviceResult is ServiceRequestFailure) {
      debugPrint("service result is faliure !");
    }

    var weekDay = DateTime.now().weekday;

    // logic to reschedule alarm in repetition pattern.
    // await LocalAlarmService.rescheduleAlarm(alarmModel, weekDay);
  } catch (e) {
    debugPrint("Error : $e");
    throw Exception("Something went wrong, after triggering alarmCallback");
  }
}

这是管理flutter的前景服务班的前景服务班

@pragma('vm:entry-point')
void startForegroundTaskCallback() {
  FlutterForegroundTask.setTaskHandler(ForegroundServiceHandler());
}

@pragma('vm:entry-point')
void alarmCallback(int id, Map<String, dynamic> params) async {
  debugPrint("The alarm callback is running !");
  bool isRunningService = await FlutterForegroundTask.isRunningService;

  debugPrint("The foreground service is running : $isRunningService");

  if (!isRunningService) {
    debugPrint("Init foreground task");
    ForegroundTaskService.init();
  } else {
    debugPrint("restart foreground task");
    await FlutterForegroundTask.restartService();
  }

  try {
    var map = params['params'] as Map<String, dynamic>;
    var alarmModel = Alarmsmodel.fromMap(map);

    debugPrint(alarmModel.toString());

    assert(alarmModel.audioPath != null,
        " Cannot play audio because ,audio path is null !");

    
    ForegroundTaskService.saveData("audioPath", alarmModel.audioPath);
    ServiceRequestResult serviceResult =
        await ForegroundTaskService.startService();

    if (serviceResult is ServiceRequestSuccess) {
      debugPrint("service result is success !");
    } else if (serviceResult is ServiceRequestFailure) {
      debugPrint("service result is faliure !");
    }

    var weekDay = DateTime.now().weekday;

    // logic to reschedule alarm in repetition pattern.
    // await LocalAlarmService.rescheduleAlarm(alarmModel, weekDay);
  } catch (e) {
    debugPrint("Error : $e");
    throw Exception("Something went wrong, after triggering alarmCallback");
  }
}

the the the the theForegroundServiceHandler的代码

class ForegroundServiceHandler extends TaskHandler {
  @override
  Future<void> onStart(DateTime timestamp, TaskStarter starter) async {
    debugPrint("Fetching audio path.");

    String? audioPath =
        await FlutterForegroundTask.getData<String>(key: 'audioPath');
    debugPrint("The audio path is $audioPath");

    if (audioPath != null && audioPath.isNotEmpty) {
      debugPrint(
          "The audio path is not null neither its empty . Audiopath is $audioPath");
      AudioService.instance.playAudioInForeground(audioPath);
    } else {
      debugPrint(
          "Error : audioPath is missing. (ForegroundServiceHandler)(onStart)");
    }
  }

  @override
  void onNotificationButtonPressed(String id) {
    super.onNotificationButtonPressed(id);
    debugPrint("onNotificationButtonPressed");

    if (id == "stop_audio") {
      AudioService.instance.stopAudio();
    }
    FlutterForegroundTask.stopService();

  }

  @override
  void onNotificationPressed() {
    super.onNotificationPressed();
    debugPrint("onNotificationPressed");
  }

  @override
  void onNotificationDismissed() {
    super.onNotificationDismissed();
    debugPrint("onNotificationDismissed");
    FlutterForegroundTask.stopService();
  }

  @override
  void onReceiveData(Object data) {
    super.onReceiveData(data);
    debugPrint("onReceiveData");
  }

  @override
  void onRepeatEvent(DateTime timestamp) {}

  @override
  Future<void> onDestroy(DateTime timestamp) async {
    debugPrint("onDestroy invoked. Stopping service");
  }
}

这是我的代码

audio服务

class AudioService {
  AudioPlayer? _audioPlayer;
  bool isAudioPlaying = false;

  static final AudioService instance = AudioService._internal();

  factory AudioService() {
    return instance;
  }

  AudioService._internal() {
    _audioPlayer = AudioPlayer();
    _audioPlayer?.setReleaseMode(ReleaseMode.loop);
    _audioPlayer?.onPlayerStateChanged.listen((PlayerState state) {
      isAudioPlaying = (state == PlayerState.playing);
    });
  }

  void disposeAudio() {
    _audioPlayer?.dispose();
    _audioPlayer = null;
  }

  void playAudio(String path) async {
    if (_audioPlayer == null) {
      debugPrint("Audio player instance is null !");
    } else {
      debugPrint("Audio Player instance is not null !");
    }

    _audioPlayer ??= AudioPlayer(); //ensure its initialized.

    if (isAudioPlaying) {
      await _audioPlayer?.stop();
    }

    debugPrint("Playing audio for audiopath : $path");
    await _audioPlayer?.play(
      AssetSource(path),
      volume: 1,
    );
  }

  void stopAudio() async {
    _audioPlayer ??= AudioPlayer();
    debugPrint("Stopping audio instance hashcode : ${_audioPlayer.hashCode}");

    await _audioPlayer!.stop();
  }

  void playAudioInForeground(String path) async {
    String localPath = await getLocalFilePath(path);

    debugPrint("Setting audio source url");

    debugPrint("playing deviceFilePath .");
    await _audioPlayer?.play(DeviceFileSource(localPath), volume: 1);
  }

  Future<String> getLocalFilePath(String assetPath) async {
    // Get the app's document directory.
    final directory = await getApplicationDocumentsDirectory();
    final filePath = '${directory.path}/$assetPath';
    debugPrint("File path is $filePath");

    final file = File(filePath);
    bool isFilePresent = await file.exists();
    debugPrint("Does file exists $isFilePresent");

    if (!file.existsSync()) {
      // load assets as bytes.
      debugPrint("loading bytes from rootbundle");
      ByteData data = await rootBundle.load("assets/$assetPath");

      debugPrint("loading bytes from ByteData");
      List<int> bytes = data.buffer.asUint8List();

      debugPrint("The bytes length is ${bytes.length}");
      await file.create(recursive: true);
      await file.writeAsBytes(bytes);

      debugPrint("written to file");
    }

    debugPrint("returning device file path - $filePath");
    return filePath;
  }
}

看起来，当应用程序终止时，您的警报通知正在工作，但是警报音频没有播放。主要问题可能与Android中的背景执行限制有关。以下是一些可能的原因和解决方案： 修改AlarmCallback，如果应用程序未运行，请明确重新启动前景服务：

@pragma('vm:entry-point')
void alarmCallback(int id, Map<String, dynamic> params) async {
  debugPrint("The alarm callback is running !");
  
  // Ensure the Foreground Task is Running
  bool isRunningService = await FlutterForegroundTask.isRunningService;

  if (!isRunningService) {
    debugPrint("Starting foreground service...");
    ForegroundTaskService.init();
    await Future.delayed(Duration(seconds: 2)); // Small delay to ensure service starts
  } 

  debugPrint("Restarting foreground service...");
  await FlutterForegroundTask.restartService();

  try {
    var map = params['params'] as Map<String, dynamic>;
    var alarmModel = Alarmsmodel.fromMap(map);

    assert(alarmModel.audioPath != null, "Cannot play audio - Path is null!");

    // Save audio path to ForegroundTask
    ForegroundTaskService.saveData("audioPath", alarmModel.audioPath);

    ServiceRequestResult serviceResult = await ForegroundTaskService.startService();

    if (serviceResult is ServiceRequestSuccess) {
      debugPrint("Foreground service started successfully!");
    } else {
      debugPrint("Failed to start foreground service.");
    }

  } catch (e) {
    debugPrint("Error in alarmCallback: $e");
  }
}

确保音频播放正确始于Onstart内部：

Answer 1

更改文件路径的处理方式，以确保正确加载警报音频文件。

class AudioService {
  AudioPlayer? _audioPlayer;

  static final AudioService instance = AudioService._internal();

  factory AudioService() {
    return instance;
  }

  AudioService._internal() {
    _audioPlayer = AudioPlayer();
    _audioPlayer?.setReleaseMode(ReleaseMode.loop);
  }

  Future<void> playAudioInForeground(String path) async {
    String localPath = await getLocalFilePath(path);

    debugPrint("Playing audio from local path: $localPath");

    try {
      await _audioPlayer?.setSource(DeviceFileSource(localPath));
      await _audioPlayer?.setVolume(1.0);
      await _audioPlayer?.play(DeviceFileSource(localPath));
    } catch (e) {
      debugPrint("Error playing audio: $e");
    }
  }

  Future<String> getLocalFilePath(String assetPath) async {
    final directory = await getApplicationDocumentsDirectory();
    final filePath = '${directory.path}/$assetPath';
    
    final file = File(filePath);
    if (!file.existsSync()) {
      ByteData data = await rootBundle.load("assets/$assetPath");
      List<int> bytes = data.buffer.asUint8List();
      await file.create(recursive: true);
      await file.writeAsBytes(bytes);
    }
    
    return filePath;
  }

  void stopAudio() async {
    await _audioPlayer?.stop();
  }
}

AndroidManifest.xml in android/app/src/main/main/androidManifest.xml中的Addd前景服务权限，添加：

<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
<uses-permission android:name="android.permission.WAKE_LOCK"/>

declare前景服务在androidmanifest.xml内部...，添加：

<service
    android:name="com.example.alarm.ForegroundService"
    android:foregroundServiceType="mediaPlayback"
    android:permission="android.permission.FOREGROUND_SERVICE"/>

屏蔽用户将应用程序添加到主屏幕中：

import 'package:device_info_plus/device_info_plus.dart';
import 'package:battery_optimization/battery_optimization.dart';

void requestBatteryOptimizationPermission() async {
  bool isIgnoring = await BatteryOptimization.isIgnoringBatteryOptimizations();
  if (!isIgnoring) {
    await BatteryOptimization.openBatteryOptimizationSettings();
  }
}

call requestBatteryOptimizationpermission（）应用程序启动

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  requestBatteryOptimizationPermission();
  runApp(MyApp());
}