android - 蓝牙连接的线程在连接后立即关闭 socket

Question

我有一个Android应用程序，其最新版本的类型为Android API(29)。用户可以搜索附近的蓝牙设备并连接到它们以发送数据。蓝牙连接是在应用程序作为客户端的情况下进行的。

我从Anroid的文档中复制了许多代码，并对其进行了更改以满足自己的需求。该应用程序确实找到了设备，可以正确配对并连接。

问题是，在连接后，当它尝试读取传入流时，在Connected线程中的第一个循环上，将引发异常，并且套接字断开连接。

我已直接连接到设备的正确uuid，以测试通过可能的服务器蓝牙uuid的循环是否会干扰rfcomsocket。
我尝试在循环中的连接线程中尝试读取mInputStream.available() > 0，然后再尝试读取，但看来它也引发了异常。

为了测试连接，我激活了笔记本电脑的蓝牙适配器并将其设置为接收文件(作为服务器)。我曾经在Xamarin.Android中拥有此应用程序，而代码也曾以这种方式工作。目前，它在Kotlin中运行。

下面的代码介绍了从相应函数调用的Connect和Connected线程。

fun connect(device: BluetoothDevice, uuids: ArrayList<ParcelUuid>) {
    if (connectionState == STATE_CONNECTING) {
        if (connectThread != null) {
            connectThread?.cancel()
            connectThread = null
        }
    }

    // Cancel any thread currently running a connection
    if (connectedThread != null) {
        connectedThread?.cancel()
        connectedThread = null
    }
    connectThread = ConnectThread(device, this, uuids)
    connectThread?.start()
}


private inner class ConnectThread(
    val device: BluetoothDevice,
    service: BTService,
    val uuids: ArrayList<ParcelUuid>
) : Thread() {

    var socket: BluetoothSocket? = null

    init {
        service.connectionState = STATE_CONNECTING
    }

    override fun run() {
        // Cancel discovery because it otherwise slows down the connection.
        btAdapter?.cancelDiscovery()

        for (uuid in uuids) {
            try {

                val mmSocket: BluetoothSocket? by lazy(LazyThreadSafetyMode.NONE) {
                    device.createRfcommSocketToServiceRecord(uuid.uuid)
                }
                mmSocket?.use { thisSocket ->
                    // Connect to the remote device through the socket. This call blocks
                    // until it succeeds or throws an exception.
                    thisSocket.connect()

                    // The connection attempt succeeded. Perform work associated with
                    // the connection in a separate thread.
                    socket = thisSocket
                    connected(thisSocket)
                }
                break
            } catch (e: IOException) {
                // Close the socket
                cancel()

                // Start the service over to restart listening mode
                Log.e(TAG, "unable to connect() to socket.", e)
            }
        }
    }

    // Closes the client socket and causes the thread to finish.
    fun cancel() {
        try {
            socket?.close()
        } catch (e: IOException) {
            Log.e(TAG, "Could not close the client socket", e)
        }
    }
}


//#####################################                     #####################################
//#####################################----->Connected<-----#####################################
//#####################################                     #####################################

// Start the ConnectedThread to begin managing a Bluetooth connection
fun connected(socket: BluetoothSocket) {
    // Cancel the thread that completed the connection
    if (connectThread != null) {
        connectThread?.cancel()
        connectThread = null
    }

    // Cancel any thread currently running a connection
    if (connectedThread != null) {
        connectedThread?.cancel()
        connectedThread = null
    }

    // Start the thread to manage the connection and perform transmissions
    connectedThread = ConnectedThread(socket)
    connectedThread?.start()

    // Send the name of the connected device back to the UI Activity
    MainActivity.settingsFragment?.activity?.runOnUiThread {
        (MainActivity.settingsFragment as SettingsFragment).btConnected()
    }

}

private inner class ConnectedThread(private val mmSocket: BluetoothSocket) : Thread() {

    private val mmInStream: InputStream = mmSocket.inputStream
    private val mmOutStream: OutputStream = mmSocket.outputStream
    private val mmBuffer: ByteArray = ByteArray(1024) // mmBuffer store for the stream

    init {
        connectionState = STATE_CONNECTED
    }

    override fun run() {
        // Keep listening to the InputStream until an exception occurs.
        while (true) {
            // Read from the InputStream.
            try {
                mmInStream.read(mmBuffer)
            } catch (e: IOException) {
                connectionLost()
                Log.d(TAG, "Input stream was disconnected", e)
                break
            }
            //Do something with stream.
        }
    }

    // Call this from the main activity to send data to the remote device.
    fun write(bytes: ByteArray) {
        try {
            mmOutStream.write(bytes)
        } catch (e: IOException) {
            Log.e(TAG, "Error occurred when sending data", e)
            // Send a failure message back to the activity.

            return
        }
    }

    // Call this method from the main activity to shut down the connection.
    fun cancel() {
        try {
            mmSocket.close()
        } catch (e: IOException) {
            Log.e(TAG, "Could not close the connect socket", e)
        }
    }
}

// Stop all threads.
fun stop() {
    if (connectThread != null) {
        connectThread?.cancel()
        connectThread = null
    }

    if (connectedThread != null) {
        connectedThread?.cancel()
        connectedThread = null
    }

    connectionState = STATE_NONE
}

fun write(bytes: ByteArray) {

    if (connectionState != STATE_CONNECTED) {
        return
    }
    val temp: ConnectedThread? = connectedThread
    temp?.write(bytes)
}

fun connectionLost() {
    MainActivity.settingsFragment?.activity?.runOnUiThread {
        (MainActivity.settingsFragment as SettingsFragment).btLost()
    }
    connectionState = STATE_NONE
}

结果是由于尝试读取时发生崩溃而导致连接线程捕获了IO。我希望它只是在 Activity 连接中循环，如果有任何数据要发送给我，则可以。

我知道inputStream不会保存在任何地方(这是有意的)，但是我怀疑这是问题所在。

编辑1:
从连接开始到连接失败(结束)的调试日志...

2019-08-03 18:30:40.583 24961-25088/com.konkarapas.rcs.full.debug W/BluetoothAdapter: getBluetoothService() called with no BluetoothManagerCallback
2019-08-03 18:30:40.776 24961-25088/com.konkarapas.rcs.full.debug D/BluetoothSocket: close() this: android.bluetooth.BluetoothSocket@39f9369, channel: -1, mSocketIS: android.net.LocalSocketImpl$SocketInputStream@611f1ee, mSocketOS: android.net.LocalSocketImpl$SocketOutputStream@96eb68fmSocket: android.net.LocalSocket@15d7d1c impl:android.net.LocalSocketImpl@94fd25 fd:java.io.FileDescriptor@42f3efa, mSocketState: INIT
2019-08-03 18:30:40.780 24961-25088/com.konkarapas.rcs.full.debug E/BluetoothService: unable to connect() to socket.
    java.io.IOException: read failed, socket might closed or timeout, read ret: -1
        at android.bluetooth.BluetoothSocket.readAll(BluetoothSocket.java:762)
        at android.bluetooth.BluetoothSocket.readInt(BluetoothSocket.java:776)
        at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:399)
        at com.konkarapas.rcs.models.BTService$ConnectThread.run(BluetoothService.kt:172)
2019-08-03 18:30:40.782 24961-25088/com.konkarapas.rcs.full.debug W/BluetoothAdapter: getBluetoothService() called with no BluetoothManagerCallback
2019-08-03 18:30:40.934 24961-25088/com.konkarapas.rcs.full.debug D/BluetoothSocket: close() this: android.bluetooth.BluetoothSocket@5534f08, channel: 4, mSocketIS: android.net.LocalSocketImpl$SocketInputStream@ebd46a1, mSocketOS: android.net.LocalSocketImpl$SocketOutputStream@3a250c6mSocket: android.net.LocalSocket@fdce887 impl:android.net.LocalSocketImpl@f5253b4 fd:java.io.FileDescriptor@cc6abdd, mSocketState: CONNECTED
2019-08-03 18:30:40.938 24961-25088/com.konkarapas.rcs.full.debug D/BluetoothSocket: close() this: android.bluetooth.BluetoothSocket@5534f08, channel: 4, mSocketIS: android.net.LocalSocketImpl$SocketInputStream@ebd46a1, mSocketOS: android.net.LocalSocketImpl$SocketOutputStream@3a250c6mSocket: null, mSocketState: CLOSED
2019-08-03 18:30:40.943 24961-25089/com.konkarapas.rcs.full.debug D/BluetoothService: Input stream was disconnected
    java.io.IOException: socket closed
        at android.net.LocalSocketImpl$SocketInputStream.read(LocalSocketImpl.java:104)
        at android.bluetooth.BluetoothSocket.read(BluetoothSocket.java:555)
        at android.bluetooth.BluetoothInputStream.read(BluetoothInputStream.java:88)
        at java.io.InputStream.read(InputStream.java:101)
        at com.konkarapas.rcs.models.BTService$ConnectedThread.run(BluetoothService.kt:245)

由于错误的uuid，第一个异常(exception)是合乎逻辑的。第二个异常(exception)是问题。

Answer 1

您正在使用mmSocket?.use，它会在连接完成后自动清理(即关闭连接)。如果将其更改为mmsocket?.let，则连接完成后不应自动关闭连接。 (对于网络套接字也有完全相同的问题，请像这样修复它)