Question

I have used the BluetoothChat Example to structure the bluetooth connection in my application. The application connects correctly, and stores all paired devices correctly, but lost connections are not properly reported.

The device that my phone connects to is powered by a small battery and turns off after being idle for ~30 seconds. What I would like is for my application to notify the user when this device turns off. I had figured this would be included in the BluetoothChat Example but I do not think it is.

private class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final BluetoothDevice mmDevice;
    private String mSocketType;

    public ConnectThread(BluetoothDevice device, boolean secure) {

        mmDevice = device;
        BluetoothSocket tmp = null;
        mSocketType = secure ? "Secure" : "Insecure";

        try {
            if (secure) {
                tmp = device.createRfcommSocketToServiceRecord( MY_UUID
                        );
            } else {
                tmp = device.createInsecureRfcommSocketToServiceRecord(
                        MY_UUID );
            }
        } catch (IOException e) {
            Log.e(TAG, "Socket Type: " + mSocketType + "create() failed", e);
        }
        mmSocket = tmp;
    }

    public void run() {
        //Log.i(TAG, "BEGIN mConnectThread SocketType:" + mSocketType);
        setName("ConnectThread" + mSocketType);

        // Always cancel discovery because it will slow down a connection
        mAdapter.cancelDiscovery();

        // Make a connection to the BluetoothSocket
        try {
            // This is a blocking call and will only return on a
            // successful connection or an exception
            mmSocket.connect();
        } catch (IOException e) {
            // Close the socket
            try {
                mmSocket.close();
            } catch (IOException e2) {
                Log.e(TAG, "unable to close() " + mSocketType +
                        " socket during connection failure", e2);
            }
            connectionFailed();
            return;
        }

        // Reset the ConnectThread because we're done
        synchronized (BluetoothService.this) {
            mConnectThread = null;
        }

        // Start the connected thread
        connected(mmSocket, mmDevice, mSocketType);
    }

    public void cancel() {
        RelayAPIModel.bluetoothConnected = false;
        try {
            mmSocket.close();
        } catch (IOException e) {
            Log.e(TAG, "close() of connect " + mSocketType + " socket failed", e);
        }
    }
}

The ConnectedThread is below:

/**
 * This thread runs during a connection with a remote device.
 * It handles all incoming and outgoing transmissions.
 */
private class ConnectedThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final InputStream mmInStream;
    private final BufferedReader mmInBuffer;
    private final OutputStream mmOutStream;

    public ConnectedThread(BluetoothSocket socket, String socketType) {
        Log.d(TAG, "create ConnectedThread: " + socketType);
        mmSocket = socket;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        // Get the BluetoothSocket input and output streams
        try {
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (IOException e) {
            Log.e(TAG, "temp sockets not created", e);
        }

        RelayAPIModel.bluetoothConnected = true;
        mmInStream = tmpIn;
        mmOutStream = tmpOut;
        mmInBuffer = new BufferedReader( new InputStreamReader( mmInStream ) );
    }

    public void run(int length) {
        buffer = new byte[1024];


        // Keep listening to the InputStream while connected
        //while (true) {
            try {
                // Read from the InputStream
                bytes = mmInStream.read(buffer, 0, length);

                // Send the obtained bytes to the UI Activity
                mHandler.obtainMessage(MainMenu.MESSAGE_READ, bytes, -1, buffer)
                        .sendToTarget();
            } catch (IOException e) {

                Message msg = mHandler.obtainMessage(MainMenu.MESSAGE_TOAST);
                Bundle bundle = new Bundle();
                bundle.putString( TOAST, "Device has disconnected from the Bluetooth Module." );
                msg.setData(bundle);
                mHandler.sendMessage(msg);
                Log.e(TAG, "disconnected a", e);
                connectionLost();

                // Start the service over to restart listening mode
                BluetoothService.this.start();
                //break;
            }
       // }
    }

    /**
     * Write to the connected OutStream.
     * @param buffer  The bytes to write
     */
    public void write( byte[] buffer ) {
        try {
            mmOutStream.write(buffer);

            // Share the sent message back to the UI Activity
            mHandler.obtainMessage(MainMenu.MESSAGE_WRITE, -1, -1, buffer)
                    .sendToTarget();
        } catch (IOException e) {
            Log.e(TAG, "Exception during write", e);
        }
    }

    public void cancel() {
        RelayAPIModel.bluetoothConnected = false;
        try {
            mmSocket.close();
        } catch (IOException e) {
            Log.e(TAG, "close() of connect socket failed", e);
        }
    }
}

I also have this connectionLost function, and should be called if an exception is caught in the ConnectedThread, but the exception seems to never be caught.

private void connectionLost() {
    // Send a failure message back to the Activity
    Message msg = mHandler.obtainMessage(MainMenu.MESSAGE_TOAST);
    RelayAPIModel.bluetoothConnected = false;
    Bundle bundle = new Bundle();
    bundle.putString(TOAST, "Device connection was lost");
    msg.setData(bundle);
    mHandler.sendMessage(msg);
    Log.i("Here.",  "Connection Lost" );
    // Start the service over to restart listening mode
    BluetoothService.this.start();
}

Answer 1

Here you go, in your broadcast receiver, override onRecieve to get the disconnect intents for your bluetooth connection.

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        if (BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED.equals(action)) {
            //disconnect request
        } else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
            //disconnected, do what you want to notify user here, toast, or dialog, etc.
        }
    }
}