android - Flutter 如何在后台发现蓝牙设备（flutter_bluetooth_serial）

Question

我想在后台开始连续搜索蓝牙设备，并在检测到设备“X”时发送通知。

此时我每 5 秒运行一次定期计时器，在其中我执行新的扫描

即使我关闭了应用程序，我该如何进行此扫描？

  Timer.periodic(Duration(milliseconds: 5000), (timer) => discovery());

  void discovery() {
    var tmp = new Map<String, BluetoothDevice>();

    FlutterBluetoothSerial.instance.startDiscovery().listen((r) {
      tmp.putIfAbsent(r.device.address, () => r.device);

      app.onDiscovery(r);
    }).onDone(() {
      _isDiscovering = false;
    });
  }

我想要一个兼容 IOS 和 Android 的解决方案。

谢谢你，美好的一天。

标签： androidiosflutterdartbluetooth

Answer 1

要在后台运行任务，您可能需要考虑使用Isolate。

Isolate? isolate;

@override
void initState() {
  /// Start background task
  _asyncInit();
  super.initState();
}


_asyncInit() async {
  final ReceivePort receivePort = ReceivePort();
  isolate = await Isolate.spawn(_isolateEntry, receivePort.sendPort);

  receivePort.listen((dynamic data) {
    if (data is SendPort) {
      if (mounted) {
        data.send({
          /// Map data using key-value pair
          /// i.e. 'key' : String
        });
      }
    } else {
      if (mounted) {
        setState(() {
          /// Update data here as needed
        });
      }
    }
  });
}

static _isolateEntry(dynamic d) async {
  final ReceivePort receivePort = ReceivePort();
  d.send(receivePort.sendPort);

  /// config contains the key-value pair from _asyncInit()
  final config = await receivePort.first;
 
  /// send bluetooth data you received
  d.send(...);
}

@override
void dispose() {
  /// Determine when to terminate the Isolate
  if (isolate != null) {
    isolate.kill();
  }
  super.dispose();
}

至于 Flutter 上的 BLE 支持，您还可以考虑使用flutter_blue