안드로이드 블루투스 (classic bl) #3 데이터 송수신

//데이터 송수신하는 쓰레드

private const val TAG = "MY_APP_DEBUG_TAG"

// Defines several constants used when transmitting messages between the
// service and the UI.
const val MESSAGE_READ: Int = 0
const val MESSAGE_WRITE: Int = 1
const val MESSAGE_TOAST: Int = 2
// ... (Add other message types here as needed.)

class MyBluetoothService(
    // handler that gets info from Bluetooth service
    private val handler: Handler
) {

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

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

        override fun run() {
            var numBytes: Int // bytes returned from read()

            while (true) {
                try {
                    numBytes = mmInStream.available();
                    if (numBytes != 0) {
                        SystemClock.sleep(100);
                        numBytes = mmInStream.available();
                        numBytes = mmInStream.read(mmBuffer, 0, numBytes);
                        handler.obtainMessage(MESSAGE_READ, numBytes, -1, mmBuffer)
                            .sendToTarget(); //읽어들인 메시지를 핸들러에 보냅니다.
                    }
                } catch (e: IOException) {
                    Timber.d("Input stream was disconnected")
                    break
                }
            }
        }

        // Call this from the main activity to send data to the remote device.
        fun write(bytes: ByteArray) {
            if (!mmSocket.isConnected) {
                //socket에 연결되어 있지 않다면 return
                return
            }
            try {
                mmOutStream.write(bytes)
            } catch (e: IOException) {
                e.printStackTrace()
                //  Send a failure message back to the activity. 실패메시지를 보냅니다.
                val writeErrorMsg = handler.obtainMessage(MESSAGE_TOAST)
                val bundle = Bundle().apply {
                    putString("toast", "Couldn't send data to the other device")
                }
                writeErrorMsg.data = bundle
                handler.sendMessage(writeErrorMsg)
                return
            }
            //   Share the sent message with the Contacts.Intents.UI activity. // 보낸 메시지 내용을 UI 액티비티에 보냅니다.
            val writtenMsg = handler.obtainMessage(
                MESSAGE_WRITE, -1, -1, mmBuffer
            )
            writtenMsg.sendToTarget()
        }

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

//데이터 읽고쓰는 쓰레드와 연결된 핸들러

 val handler = object : Handler(Looper.getMainLooper()) {
        override fun handleMessage(msg: Message) {
            if (msg.what == MESSAGE_READ) {
                val readBuf = msg.obj as ByteArray
                val readMessage = String(readBuf, 0, msg.arg1)
                Timber.d("readMessage ${readMessage}")

            } else if (msg.what == MESSAGE_WRITE) {
                val writeBuf = msg.obj as ByteArray

                // construct a string from the buffer
                Timber.d("writeMessage ${String(writeBuf, Charsets.US_ASCII)}")
            }
        }
    }

//실제로 데이터 보내는 코드 

  fun Context.writeSomeThing(myBluetoothService: MyBluetoothService.ConnectedThread) {
        sendMessage("write something\r", myBluetoothService) // 여기서 \r 을 해주지 않아 엄청나게 삽질을 했습니다..ㅠㅠㅠ
    }

    private fun sendMessage(
        message: String,
        myBluetoothService: MyBluetoothService.ConnectedThread
    ) {
        if (message.isNotEmpty()) {
            // Get the message bytes and tell the BluetoothChatService to write
            val send = message.toByteArray()
            myBluetoothService.write(send)
        }
    }