无法从蓝牙流中读取字节，而不记录读取的字节数

Question

    private class ConnectedThread extends Thread {
        private /*final*/ BluetoothSocket mmSocket;
        private /*final*/ InputStream mmInStream;
        private /*final*/ OutputStream mmOutStream;

        public ConnectedThread(BluetoothSocket socket) {
            mmSocket = socket;
            InputStream tmpIn = null;
            OutputStream tmpOut = null;

            // Get the input and output streams, using temp objects because
            // member streams are final
            try {
                tmpIn = socket.getInputStream();
                tmpOut = socket.getOutputStream();
            } catch (IOException e) {
                Log.e(TAG, "Error connecting IO streams.");
            }

            mmInStream = tmpIn;
            mmOutStream = tmpOut;
        }

        public void run() {
            byte[] buffer = new byte[1024];  // buffer store for the stream
            int bytes; // bytes returned from read()

            // Keep listening to the InputStream until an exception occurs
            while (true) {
                try {
                    if ((bytes = mmInStream.read(buffer)) > 0) {
                        //Send the obtained bytes to the UI activity
                        //mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer).sendToTarget();
                        Log.i(TAG, "Read (" + bytes + ") bytes.");
                        String readBytesStr = new String(buffer, 0, bytes, "ASCII");
                        Log.i(TAG, "Bytes from stream (" + bytes + "): " + readBytesStr);
                    }
                } catch (IOException e) {
                    Log.i(TAG, "Exception occurred: stopped listening to stream.");
                    break;
                }
            }
        }

        /* Call this from the main activity to send data to the remote device */
        public void write(byte[] bytes) {
            try {
                mmOutStream.write(bytes);
            } catch (IOException e) {
                Log.e(TAG, "ConnectedThread(): Exception in write()");
            }

            String temp = new String(bytes);
            Log.i(TAG, "Wrote: " + temp);
        }

        /* Call this from the main activity to shutdown the connection */
        public void cancel() {
            try {
                mmSocket.close();
            } catch (IOException e) {
                Log.e(TAG, "ConnectedThread(): Exception in cancel()");
            }
        }
    }


// Connecting as a client
// http://developer.android.com/guide/topics/connectivity/bluetooth.html#ConnectingAsAClient
private class ConnectThread extends Thread {
    private /*final*/ BluetoothSocket mmSocket;
    private /*final*/ BluetoothDevice mmDevice;

    public ConnectThread(BluetoothDevice device) {
        // Use a temporary object that is later assigned to mmSocket,
        // because mmSocket is final
        BluetoothSocket tmp = null;
        mmDevice = device;

        // Get a BluetoothSocket to connect with the given BluetoothDevice
        try {
            // MY_UUID is the app's UUID string, also used by the server code TODO
            tmp = device.createRfcommSocketToServiceRecord(mUUID);
        } catch (IOException e) {
            Log.e(TAG, "ConnectThread() : Unable to create temp socket.");
        }
        mmSocket = tmp;
        Log.i(TAG, "Socket obtained (Connect): " + mmSocket.toString());
    }

    public void run() {
        // Cancel discovery because it will slow down the connection
        mBluetoothAdapter.cancelDiscovery();

        try {
            // Connect the device through the socket. This will block
            // until it succeeds or throws an exception
            mmSocket.connect();
        } catch (IOException connectException) {
            // Unable to connect; close the socket and get out
            Log.e(TAG, "ConnectThread().run() : Unable to connect.");
            try {
                mmSocket.close();
            } catch (IOException closeException) {
                Log.e(TAG, "ConnectThread().run() : Unable to close socket.");
            }
            return;
        }

        // Do work to manage the connection (in a separate thread) TODO
        Log.i(TAG, "ConnectThread().run() : Ready to manage connection.");
        mConnectedSocket = mmSocket;
        manageConnectedSocket(mConnectedSocket);
    }

    private void manageConnectedSocket(BluetoothSocket mmSocket) {
        mConnectedThread = new ConnectedThread(mmSocket);
        mConnectedThread.start();
    }

    /** Will cancel an in-progress connection, and close the socket */
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) { }

        mmSocket = null;
        Log.i(TAG, "ConnectThread().cancel() successful");
    }
}

我使用基于Android's example for managing a bluetooth connection的代码连接和读取/写入蓝牙模块的数据。如果我记录首先读取的字节数，我只能正确读取数据：

    Log.i(TAG, "Read (" + bytes + ") bytes.");

如果没有该行，下一个日志将不显示任何内容。

    Log.i(TAG, "Bytes from stream (" + bytes + "): " + readBytesStr);

用作业替换第一个日志没有帮助。

    int numReadBytes = bytes;

基于对this问题的回答，我也尝试使用DataInputStream的readFully（），但它从未完全读取预期的输入（尽管有足够大的缓冲区）。

为什么日志能够正常工作？