flutter - 无法从flutter_sound包成功调用startRecorder(uri:…)

我正在尝试使flutter_sound包的简单功能起作用。我正在通过首先能够开始记录来解决这个问题。似乎我当前遇到了一个问题，即使在将Uri包括到要保存这些文件的位置时，以及我希望它导出这些文件的音频格式的类型时，也遇到了问题:

flutter: NoSuchMethodError: The method 'startRecorder' was called on null.
Receiver: null
Tried calling: startRecorder(codec: Instance of 't_CODEC', uri: "/Users/<user-name>/Library/Developer/CoreSimulator/Devices/CEC7EE26-9400-479B-85EB-06728074F7C0/data/Containers/Data/Application/4C726628-AE3B-42E7-8C6A-4B239AFDFAE6/Library/Caches/audio.aac")

我检查了目录，但没有看到audio.aac文件出现，因此当我尝试使用touch audio.aac通过终端创建文件并尝试记录时，仍然出现相同的错误。因此，我假设我需要能够以某种方式创建该文件，或者我什至根本不了解问题所在。我真的很迷失，曾经有其他开发人员试图提供帮助，却找不到有关如何解决此问题的资源。

在我的pubspec.yaml中，将flutter_sound版本设置为如下所示:

dev_dependencies:
  flutter_sound: ^2.0.3

我已经在Info.plist和AndroidManifest.xml中包含了必要的权限。

我将在下面发布我认为需要的代码。

class _AudioRecorderState extends State<AudioRecorder> {
  String _recordedFilePath;
  bool _isRecording = false;
  bool _isPlaying = false;
  StreamSubscription _recorderSubscription;
  StreamSubscription _dbPeakSubscription;
  StreamSubscription _playerSubscription;
  FlutterSound flutterSound;

  String _recorderTxt = '00:00:00';
  String _playerTxt = '00:00:00';
  double _dbLevel;

  double sliderCurrentPosition = 0.0;
  double maxDuration = 1.0;

  @override
  void initState() {
    super.initState();
    FlutterSound flutterSound = new FlutterSound();
    flutterSound.setSubscriptionDuration(0.01);
    flutterSound.setDbPeakLevelUpdate(0.8);
    flutterSound.setDbLevelEnabled(true);
    initializeDateFormatting();
  }

  void startRecorder() async {
    try {
      Directory tempDir = await getTemporaryDirectory();
      File filePath = File('${tempDir.path}/audio.aac');
      String path = await flutterSound.startRecorder(uri: filePath.path, codec: t_CODEC.CODEC_AAC);
      print('startRecorder: $path');

      _recorderSubscription = flutterSound.onRecorderStateChanged.listen((e) {
        DateTime date = new DateTime.fromMillisecondsSinceEpoch(
            e.currentPosition.toInt(),
            isUtc: true);
        String txt = DateFormat('mm:ss:SS', 'en_US').format(date);

        this.setState(() {
          this._recorderTxt = txt.substring(0, 8);
        });
      });
      _dbPeakSubscription =
          flutterSound.onRecorderDbPeakChanged.listen((value) {
        print("got update -> $value");
        setState(() {
          this._dbLevel = value;
        });
      });

      this.setState(() {
        this._isRecording = true;
      });
    } catch (err) {
      print('startRecorder error: $err');
    }
  }

如果您想查看我的Widget Build(...){...}或代码的其他任何部分，请告诉我。

最佳答案

您没有正确初始化flutterSound实例

 @override
  void initState() {
    super.initState();
    //FlutterSound flutterSound = new FlutterSound();
    //you already created flutterSound at the top
    flutterSound = new FlutterSound();
    flutterSound.setSubscriptionDuration(0.01);
    flutterSound.setDbPeakLevelUpdate(0.8);
    flutterSound.setDbLevelEnabled(true);
    initializeDateFormatting();
  }