setupNotification返回“错误已连接”，而没有发送连接请求

时间：2019-04-25 07:51:58

标签： android kotlin bluetooth-lowenergy rxandroidble

我正在使用RxAndroidBLE API制作具有某些BLE特色的Android应用程序。我遵循了https://github.com/Polidea/RxAndroidBle

中的示例准则和示例

我与指定的设备建立BLE连接，稍后在连接时我没有问题地读取和写入特性，但是当我尝试设置电池电量特性的通知时，出现以下可抛出的错误消息：已通过以下方式连接到设备MAC地址XX：XX ...“

我真的不理解这种情况下的错误，因为我可以毫无问题地读写特性。

我想在初次读取它的值以用于特定目的之后为此特性设置通知。

以下是重现我的问题的示例代码：

private lateinit var device: RxBleDevice
private var connectionObservable: Observable<RxBleConnection>? = null
private var rxBleConnection: RxBleConnection? = null

private val connectionDisposable = CompositeDisposable()
private val connectionStateDisposable = CompositeDisposable()
private var notifyValueChangeSubscription = CompositeDisposable()


var enableBatteryNotificationRunnable: Runnable = Runnable {
  enableBatteryNotification()
}
private var myHandler = Handler()
val DELAY_BEFORE_ENABLE_NOTIFICATION: Long = 100


private fun connect() {
  connectionObservable = device.establishConnection(false)
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())

  connectionObservable?.let {
    connectionDisposable.add(it.subscribe(
      { rxBleConnection ->
        this.rxBleConnection = rxBleConnection
      },
      { _ ->
        Log.e("connect", "connexion error")                       
      })
    )
  }

  val state = device.observeConnectionStateChanges().subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())
  connectionStateDisposable.add(
    state.subscribe(
      { connectionState ->
        Log.i("connect", "connexion state :$connectionState")
        if(connectionState == RxBleConnection.RxBleConnectionState.CONNECTED) {
            myHandler.postDelayed(enableBatteryNotificationRunnable, DELAY_BEFORE_ENABLE_NOTIFICATION);
        }
      }
    )
    { _ ->
      Log.e("connection listener", "connexion state error")
    }
  )
}

private fun enableBatteryNotification () {
  connectionObservable?.let {
    var observableToReturn =  it
      .flatMap { it.setupNotification(UUID_BATTERY_LEVEL) }
      .doOnNext {
        Log.i("NOTIFICATION", "doOnNext")
      }
      .flatMap { it }
      .subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())

    notifyValueChangeSubscription.add(observableToReturn.subscribe({ bytes ->
        var strBytes = String(bytes)
        Log.i("NOTIFICATION", "value change: $strBytes")
      }, 
      { throwable ->
        Log.e("NOTIFICATION", "Error in notification process: " + throwable.message)
      })
    )
  }
}

在此先感谢您的帮助：）

1 个答案:

答案 0 :(得分：0)

  

setupNotification返回“已连接错误”，而没有发送连接请求

实际上发出了两个连接请求-因此出错。从RxBleDevice.establishConnection() Javadoc：

     * Establishes connection with a given BLE device. {@link RxBleConnection} is a handle, used to process BLE operations with a connected
     * device.

在您的代码中，establishConnection() Observable有两个订阅。

private lateinit var device: RxBleDevice
private var connectionObservable: Observable<RxBleConnection>? = null
private var rxBleConnection: RxBleConnection? = null

private val connectionDisposable = CompositeDisposable()
private val connectionStateDisposable = CompositeDisposable()
private var notifyValueChangeSubscription = CompositeDisposable()


var enableBatteryNotificationRunnable: Runnable = Runnable {
  enableBatteryNotification()
}
private var myHandler = Handler()
val DELAY_BEFORE_ENABLE_NOTIFICATION: Long = 100


private fun connect() {
  connectionObservable = device.establishConnection(false)
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())

  connectionObservable?.let {
    connectionDisposable.add(it.subscribe( // << Here is the first subscription
      { rxBleConnection ->
        this.rxBleConnection = rxBleConnection
      },
      { _ ->
        Log.e("connect", "connexion error")                       
      })
    )
  }

  val state = device.observeConnectionStateChanges().subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())
  connectionStateDisposable.add(
    state.subscribe(
      { connectionState ->
        Log.i("connect", "connexion state :$connectionState")
        if(connectionState == RxBleConnection.RxBleConnectionState.CONNECTED) {
            myHandler.postDelayed(enableBatteryNotificationRunnable, DELAY_BEFORE_ENABLE_NOTIFICATION);
        }
      }
    )
    { _ ->
      Log.e("connection listener", "connexion state error")
    }
  )
}

private fun enableBatteryNotification () {
  connectionObservable?.let {
    var observableToReturn =  it
      .flatMap { it.setupNotification(UUID_BATTERY_LEVEL) }
      .doOnNext {
        Log.i("NOTIFICATION", "doOnNext")
      }
      .flatMap { it }
      .subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())

    notifyValueChangeSubscription.add(observableToReturn.subscribe({ bytes -> // << Here is the second subscription
        var strBytes = String(bytes)
        Log.i("NOTIFICATION", "value change: $strBytes")
      }, 
      { throwable ->
        Log.e("NOTIFICATION", "Error in notification process: " + throwable.message)
      })
    )
  }
}

这种情况是人们学习RxJava的普遍困惑。 three paths可以解决您的问题。从最少到最多的工作：

共享establishConnection Observable

可以与RxReplayingShare共享一个RxBleConnection。更改此：

  connectionObservable = device.establishConnection(false)
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())

对此：

  connectionObservable = device.establishConnection(false)
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .compose(ReplayingShare.instance())

使用rxBleConnection: RxBleConnection?属性

代替：

  connectionObservable?.let {
    var observableToReturn =  it
      .flatMap { it.setupNotification(UUID_BATTERY_LEVEL) }
      .doOnNext {
        Log.i("NOTIFICATION", "doOnNext")
      }
      .flatMap { it }
      .subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())

    notifyValueChangeSubscription.add(observableToReturn.subscribe({ bytes -> // << Here is the second subscription
        var strBytes = String(bytes)
        Log.i("NOTIFICATION", "value change: $strBytes")
      }, 
      { throwable ->
        Log.e("NOTIFICATION", "Error in notification process: " + throwable.message)
      })
    )
  }

制作：

  rxBleConnection?.let {
    var observableToReturn = rxBleConnection.setupNotification(UUID_BATTERY_LEVEL)
      .doOnNext {
        Log.i("NOTIFICATION", "doOnNext")
      }
      .flatMap { it }
      .subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())

    notifyValueChangeSubscription.add(observableToReturn.subscribe({ bytes -> // << Here is the second subscription
        var strBytes = String(bytes)
        Log.i("NOTIFICATION", "value change: $strBytes")
      }, 
      { throwable ->
        Log.e("NOTIFICATION", "Error in notification process: " + throwable.message)
      })
    )
  }

不建议这样做，因为您可能会以RxBleConnection结尾而不再有效，因为它可能在致电enableBatteryNotification()之前已断开连接

更改代码流以使用单个.subscribe()

这是根据您的确切用例量身定制的解决方案。不幸的是，您添加的信息不足以创建插入式代码替换，但看起来可能像这样：

device.establishConnection(false)
    .flatMap { connection ->
        Observable.merge(
            connection.readCharacteristic(uuid0).map { ReadResult(uuid0, it) }.toObservable(),
            connection.setupNotification(uuid1).flatMap { it }.map { NotifyResult(uuid1, it) }.delaySubscription(100, TimeUnit.MILLISECONDS)
        )
    }
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(
        { /* handle ReadResult/NotifyResult */ },
        { /* handle potential errors */ }
    )

其中ReadResult和NotifyResult将是data class，其中UUID和ByteArray

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