Xamarin.Android 无法在 Android 10 (Q) 中将录制的自定义声音用于推送通知

Question

这曾经可以工作，录制声音以用于推送通知通道的自定义声音。现在它不再了。 请问有什么变化，为什么不再起作用了，通知进来时没有声音？

为了将录制的声音用于推送通知，我曾经将其复制到外部存储中，这样可以在运行时访问它：

外部路径的路径是这样的：

/storage/emulated/0/customNotificationSoundRecording.wav

这里是完整代码，先录声音：

private async Task RecordAudio()
        {
            buttonSave.IsEnabled = false;
            try
            {
                if (!recorder.IsRecording)
                {                
                    buttonRecord.IsEnabled = false;
                    buttonPlay.IsEnabled = false;               

                    // only if ios
                    if (Device.RuntimePlatform == Device.iOS)
                        DependencyService.Get<IAudioService>().PrepareRecording();


                    Increment = 1 / (double)AppConstants.MAX_RECORD_TIME;
                    Set_Timer();

                    var recordTask = await recorder.StartRecording();

                    buttonRecord.Text = "Stop";
                    buttonRecord.IsEnabled = true;

                    // get the recorded file
                    var recordedAudioFile = await recordTask;
                    // isRecording = false;                  

                    if (recordedAudioFile != null)
                    {
                        // first save the file from cache to AppData
                        var recordingFileDestinationPath = Path.Combine(FileSystem.AppDataDirectory, AppConstants.CUSTOM_ALERT_FILENAME);                     

                        //if (File.Exists(recordingFileDestinationPath))
                        if (CustomAlertSoundExists(recordingFileDestinationPath))
                        {
                            File.Delete(recordingFileDestinationPath);
                        }

                        File.Copy(recordedAudioFile, recordingFileDestinationPath);                     

                        Preferences.Set(AppConstants.CUSTOM_RECORDING_EXISTS_KEY, true);

                        if (Device.RuntimePlatform == Device.iOS)
                        {
                            DependencyService.Get<IGroupUserPrefs>().SetBoolValueForKey("isCustomAlert", true);
                        }

                        buttonSave.IsEnabled = true;
                    }

                    if (secondsElapsed >= AppConstants.MAX_RECORD_TIME)
                    {
                        Preferences.Set(AppConstants.RECORDING_LENGTH_SECONDS_KEY, secondsElapsed);
                        secondsElapsed = 0;
                        Reset_Timer();
                    }

                    buttonRecord.Text = "Record";
                    buttonPlay.IsEnabled = true;

                }
                else // stop button clicked
                {                                  

                    buttonRecord.IsEnabled = false;

                    await recorder.StopRecording();
                    buttonSave.IsEnabled = true;

                    // isRecording = false;

                    Reset_Timer();

                    // save last recording length in seconds
                    Preferences.Set(AppConstants.RECORDING_LENGTH_SECONDS_KEY, secondsElapsed);

                    //reset seconds elapsed 
                    secondsElapsed = 0;

                    buttonRecord.IsEnabled = true;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

然后将录音复制到外部存储，它曾经是它可以用于推送通知声音的唯一位置：

public async void CopyRecordingToExternalStorage(string filePath)
        {
            var recordingFileExternalPath = Path.Combine(Android.OS.Environment.ExternalStorageDirectory.Path, AppConstants.CUSTOM_ALERT_FILENAME);

             // made some other attempts with different paths.
            // var recordingFileExternalPath = Path.Combine(FileSystem.AppDataDirectory, AppConstants.CUSTOM_ALERT_FILENAME);
            //var recordingFileExternalPath = Path.Combine(Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryAlarms).AbsolutePath, AppConstants.CUSTOM_ALERT_FILENAME);

            var storageStatus = await CrossPermissions.Current.CheckPermissionStatusAsync(Plugin.Permissions.Abstractions.Permission.Storage);

            if (storageStatus != Plugin.Permissions.Abstractions.PermissionStatus.Granted)
            {
                var results = await CrossPermissions.Current.RequestPermissionsAsync(new[] { Plugin.Permissions.Abstractions.Permission.Storage });
                storageStatus = results[Plugin.Permissions.Abstractions.Permission.Storage];
            }

            if (storageStatus == Plugin.Permissions.Abstractions.PermissionStatus.Granted)
            {
                try
                {
                    if (File.Exists(recordingFileExternalPath))  // if file exists already in external storage
                    {
                        File.Delete(recordingFileExternalPath); // erase the file
                    }

                    File.Copy(filePath, recordingFileExternalPath); // and overwrite with new one
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
            }
            else
            {
                UserDialogs.Instance.Alert("Permission to write to External Storage denied, cannot save settings.", "Permission Denied", "Ok");
            }             
        }

然后我会用这样的声音创建一个频道：

private void createCustomNotificationChannel()
        {
            try
            {
                // the custom channel
                var urgentChannelName = GetString(Resource.String.noti_chan_custom);
                var customChannelDescription = GetString(Resource.String.noti_chan_custom_description);

                long[] customVibrationPattern = { 100, 30, 100, 30, 100, 200, 200, 30, 200, 30, 200, 200, 100, 30, 100, 30, 100, 100, 30, 100, 30, 100, 200, 200, 30, 200, 30, 200, 200, 100, 30, 100, 30, 100 };

                // Creating an Audio Attribute
                var alarmAttributes = new AudioAttributes.Builder()
                    .SetContentType(AudioContentType.Sonification)
                    .SetUsage(AudioUsageKind.Notification).Build();

                var alarmSourcePath = System.IO.Path.Combine(Android.OS.Environment.ExternalStorageDirectory.Path, AppConstants.CUSTOM_ALERT_FILENAME);

                 // also tried here with other paths
                // var alarmSourcePath = Path.Combine(FileSystem.AppDataDirectory, AppConstants.CUSTOM_ALERT_FILENAME);
                // var alarmSourcePath = System.IO.Path.Combine(Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryAlarms).AbsolutePath, AppConstants.CUSTOM_ALERT_FILENAME);

                var urgentAlarmUri = Android.Net.Uri.Parse(alarmSourcePath);

                // checking here if file exists after voice recording and
                //  the bool is true
                bool soundFileExists = File.Exists(alarmSourcePath);

                var chan3 = new NotificationChannel(TERTIARY_CHANNEL_ID, urgentChannelName, NotificationImportance.High)
                {
                    Description = customChannelDescription
                };

                // set the urgent channel properties
                chan3.EnableLights(true);
                chan3.LightColor = Android.Graphics.Color.Red;
                chan3.SetSound(urgentAlarmUri, alarmAttributes);
                chan3.EnableVibration(true);
                chan3.SetVibrationPattern(customVibrationPattern);
                chan3.SetBypassDnd(true);
                chan3.LockscreenVisibility = NotificationVisibility.Public;

                var manager = (NotificationManager)GetSystemService(NotificationService);

                // create chan1  which is the urgent notifications channel
                manager.CreateNotificationChannel(chan3);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }

Answer 1

为了让用户更好地控制他们的文件并限制文件混乱，默认情况下，面向 Android 10（API 级别 29）及更高版本的应用被授予对外部存储设备或范围存储的范围访问权限。此类应用程序只能看到其应用程序特定的目录（使用Context.getExternalFilesDir() 访问）和特定类型的媒体。使用范围存储是最佳做法，除非您的应用需要访问不在应用特定目录或MediaStore 中的文件。您可以参考Manage scoped external storage access。

如果你不想改变，你想坚持以前的工作。

对于 Android Q，您可以尝试将 android:requestLegacyExternalStorage="true" 添加到清单中的 <application> 元素。