How to keep Bluetooth connection background?
I have created a Bluetooth Activity class in the android app, which works fine for all the Bluetooth functionalities like: scanning, pairing, connecting, sending and receiving data.
The real problem is when the Activity is destroyed. Bluetooth is disconnecting.
how can I make Bluetooth connection throughout the app. and I want to send data to the Bluetooth from other activities.
Help me to implement this in an easy way?
public class BTActivity extends AppCompatActivity {
ArrayList<BluetoothDevice> devices = new ArrayList<>();
BluetoothAdapter mBluetoothAdapter;
BluetoothDevice mBluetoothDevice;
ArrayAdapter<BluetoothDevice> arrayAdapter;
ConnectThread c;
private static final String TAG = "MY_BT";
ListView lvPaired;
Button BluetoothOnOff, ScanBt, pairedlist, sendButton, btDisconnect, incrementBtn, decrementBtn;
EditText input_text;
TextView ConnectedTo;
FragmentManager fm = getSupportFragmentManager();
UUID BHANU_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bt);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
lvPaired = findViewById(R.id.btPairedLV);
pairedlist = findViewById(R.id.btPaired);
input_text = findViewById(R.id.user_input);
sendButton = findViewById(R.id.btnSend);
BluetoothOnOff = findViewById(R.id.offOn_bt);
ScanBt = findViewById(R.id.scan_bt);
ConnectedTo = findViewById(R.id.current_connected_bluetooth);
btDisconnect = findViewById(R.id.bt_disconnect);
incrementBtn = findViewById(R.id.incrementBtn);
decrementBtn = findViewById(R.id.decrementBtn);
onClickListener();
pairedList();
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
registerReceiver(mReceiver, filter);
}
public void onClickListener(){
pairedlist.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (arrayAdapter != null){
arrayAdapter.clear();
}
pairedList();
}
});
lvPaired.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
BluetoothDevice device = (BluetoothDevice) parent.getItemAtPosition(position);
c = new ConnectThread(device, true);
c.start();
}
});
sendButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = input_text.getText().toString();
c.sendData(text);
input_text.setText("");
}
});
BluetoothOnOff.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (!mBluetoothAdapter.isEnabled()){
mBluetoothAdapter.enable();
BluetoothOnOff.setText("ON");
}else {
mBluetoothAdapter.disable();
BluetoothOnOff.setText("OFF");
}
}
});
ScanBt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ScanFragment scanFragment = new ScanFragment();
scanFragment.show(fm,"ScanBT");
//ScanFragment scanFragment = new ScanFragment();
//scanFragment.show(fm,"Scan Fragment");
}
});
btDisconnect.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
c.cancel();
}
});
incrementBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
c.sendData("a");
}
});
decrementBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
c.sendData("b");
}
});
}
public void toast(String message) {
Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
}
@Override
protected void onDestroy() {
unregisterReceiver(mReceiver);
super.onDestroy();
}
public void pairedList() {
//arrayAdapter.clear();
devices.addAll(mBluetoothAdapter.getBondedDevices());
arrayAdapter = new ArrayAdapter<BluetoothDevice>(this, android.R.layout.simple_list_item_1,android.R.id.text1, devices);
lvPaired.setAdapter(arrayAdapter);
arrayAdapter.notifyDataSetChanged();
}
BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
toast("connected");
BluetoothDevice device = intent
.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
ConnectedTo.setText(device.getName());
btDisconnect.setVisibility(View.VISIBLE);
//getActionBar().setSubtitle(device.getName());
Log.d("BT", "connected to");
} else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
toast("disconnected");
ConnectedTo.setText("None");
btDisconnect.setVisibility(View.INVISIBLE);
// getActionBar().setSubtitle("");
Log.d("BT", "disconnected");
}
}
};
public class ConnectThread extends Thread {
BluetoothDevice cDevice;
BluetoothSocket socket;
ConnectedThread ct;
ConnectThread(BluetoothDevice device, boolean insecureConnection) {
cDevice = device;
try {
if (insecureConnection) {
socket = device.createInsecureRfcommSocketToServiceRecord(BHANU_UUID);
} else {
socket = device.createRfcommSocketToServiceRecord(BHANU_UUID);
}
} catch (IOException e) {
e.getMessage();
}
}
public void run() {
mBluetoothAdapter.cancelDiscovery();
try {
Log.d("BT", "Socket ready to connect");
socket.connect();
Log.d("BT", "Socket connected");
// out = socket.getOutputStream();
// input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
} catch (final IOException e) {
e.getMessage();
}
ct = new ConnectedThread(socket);
//ct.write("Q-smart".getBytes());
/*try {
socket.close();
} catch (final IOException closeException) {
closeException.getMessage();
}*/
}
private void sendData(String message){
Log.d(TAG,message);
if (socket != null){
ct.write(message.getBytes());
}else {
toast("Please connect to bluetooth first");
}
}
public void cancel() {
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
private byte[] mmBuffer; // mmBuffer store for the stream
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();
} catch (IOException e) {
Log.e(TAG, "Error occurred when creating input stream", e);
}
try {
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "Error occurred when creating output stream", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
mmBuffer = new byte[1024];
int numBytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs.
while (true) {
try {
// Read from the InputStream.
numBytes = mmInStream.read(mmBuffer);
// Send the obtained bytes to the UI activity.
/* Message readMsg = mHandler.obtainMessage(
MessageConstants.MESSAGE_READ, numBytes, -1,
mmBuffer);
readMsg.sendToTarget();*/
} catch (IOException e) {
Log.d(TAG, "Input stream was disconnected", e);
break;
}
}
}
// Call this from the main activity to send data to the remote device.
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
// Share the sent message with the UI activity.
/* Message writtenMsg = mHandler.obtainMessage(
MessageConstants.MESSAGE_WRITE, -1, -1, mmBuffer);
writtenMsg.sendToTarget();*/
} catch (IOException e) {
Log.e(TAG, "Error occurred when sending data", e);
// Send a failure message back to the activity.
/* Message writeErrorMsg =
mHandler.obtainMessage(MessageConstants.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString("toast",
"Couldn't send data to the other device");
writeErrorMsg.setData(bundle);
mHandler.sendMessage(writeErrorMsg);*/
}
}
}
}
Answer
Yes, I found working solution for running Bluetooth background in android. Below is the code I have used in my android app.
public class BluetoothServices extends Service {
private BluetoothAdapter mBluetoothAdapter;
public static final String B_DEVICE = "MY DEVICE";
public static final String B_UUID = "00001101-0000-1000-8000-00805f9b34fb";
// 00000000-0000-1000-8000-00805f9b34fb
public static final int STATE_NONE = 0;
public static final int STATE_LISTEN = 1;
public static final int STATE_CONNECTING = 2;
public static final int STATE_CONNECTED = 3;
private ConnectBtThread mConnectThread;
private static ConnectedBtThread mConnectedThread;
private static Handler mHandler = null;
public static int mState = STATE_NONE;
public static String deviceName;
public static BluetoothDevice sDevice = null;
public Vector<Byte> packData = new Vector<>(2048);
//IBinder mIBinder = new LocalBinder();
@Nullable
@Override
public IBinder onBind(Intent intent) {
//mHandler = getApplication().getHandler();
return mBinder;
}
public void toast(String mess){
Toast.makeText(this,mess,Toast.LENGTH_SHORT).show();
}
private final IBinder mBinder = new LocalBinder();
public class LocalBinder extends Binder {
BluetoothServices getService() {
// Return this instance of LocalService so clients can call public methods
return BluetoothServices.this;
}
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
String deviceg = intent.getStringExtra("bluetooth_device");
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
connectToDevice(deviceg);
return START_STICKY;
}
private synchronized void connectToDevice(String macAddress){
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(macAddress);
if (mState == STATE_CONNECTING){
if (mConnectThread != null){
mConnectThread.cancel();
mConnectThread = null;
}
}
if (mConnectedThread != null){
mConnectedThread.cancel();
mConnectedThread = null;
}
mConnectThread = new ConnectBtThread(device);
toast("connecting");
mConnectThread.start();
setState(STATE_CONNECTING);
}
private void setState(int state){
mState = state;
if (mHandler != null){
// mHandler.obtainMessage();
}
}
public synchronized void stop(){
setState(STATE_NONE);
if (mConnectThread != null){
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null){
mConnectedThread.cancel();
mConnectedThread = null;
}
if (mBluetoothAdapter != null){
mBluetoothAdapter.cancelDiscovery();
}
stopSelf();
}
public void sendData(String message){
if (mConnectedThread!= null){
mConnectedThread.write(message.getBytes());
toast("sent data");
}else {
Toast.makeText(BluetoothServices.this,"Failed to send data",Toast.LENGTH_SHORT).show();
}
}
@Override
public boolean stopService(Intent name) {
setState(STATE_NONE);
if (mConnectThread != null){
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null){
mConnectedThread.cancel();
mConnectedThread = null;
}
mBluetoothAdapter.cancelDiscovery();
return super.stopService(name);
}
/*private synchronized void connected(BluetoothSocket mmSocket){
if (mConnectThread != null){
mConnectThread.cancel();
mConnectThread = null;
}
if (mConnectedThread != null){
mConnectedThread.cancel();
mConnectedThread = null;
}
mConnectedThread = new ConnectedBtThread(mmSocket);
mConnectedThread.start();
setState(STATE_CONNECTED);
}*/
private class ConnectBtThread extends Thread{
private final BluetoothSocket mSocket;
private final BluetoothDevice mDevice;
public ConnectBtThread(BluetoothDevice device){
mDevice = device;
BluetoothSocket socket = null;
try {
socket = device.createInsecureRfcommSocketToServiceRecord(UUID.fromString(B_UUID));
} catch (IOException e) {
e.printStackTrace();
}
mSocket = socket;
}
@Override
public void run() {
mBluetoothAdapter.cancelDiscovery();
try {
mSocket.connect();
Log.d("service","connect thread run method (connected)");
SharedPreferences pre = getSharedPreferences("BT_NAME",0);
pre.edit().putString("bluetooth_connected",mDevice.getName()).apply();
} catch (IOException e) {
try {
mSocket.close();
Log.d("service","connect thread run method ( close function)");
} catch (IOException e1) {
e1.printStackTrace();
}
e.printStackTrace();
}
//connected(mSocket);
mConnectedThread = new ConnectedBtThread(mSocket);
mConnectedThread.start();
}
public void cancel(){
try {
mSocket.close();
Log.d("service","connect thread cancel method");
} catch (IOException e) {
e.printStackTrace();
}
}
}
private class ConnectedBtThread extends Thread{
private final BluetoothSocket cSocket;
private final InputStream inS;
private final OutputStream outS;
private byte[] buffer;
public ConnectedBtThread(BluetoothSocket socket){
cSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
} catch (IOException e) {
e.printStackTrace();
}
try {
tmpOut = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
inS = tmpIn;
outS = tmpOut;
}
@Override
public void run() {
buffer = new byte[1024];
int mByte;
try {
mByte= inS.read(buffer);
} catch (IOException e) {
e.printStackTrace();
}
Log.d("service","connected thread run method");
}
public void write(byte[] buff){
try {
outS.write(buff);
} catch (IOException e) {
e.printStackTrace();
}
}
private void cancel(){
try {
cSocket.close();
Log.d("service","connected thread cancel method");
} catch (IOException e) {
e.printStackTrace();
}
}
}
@Override
public void onDestroy() {
this.stop();
super.onDestroy();
}
}