Android BLE startLeScan scan for already connected device

Question

I'm currently connecting my android device with another bluetooth device using BLE.

The issue is, how do I scan for already connected devices?

In my first approach, I did not call stopLeScan before the connection method.

This had no problem with the above issue, but it caused the ui to break(too short interval ui update) and sometimes connection time to be very very slow.

After I made my app to call stopLeDevice before connection, every issuses has been resolved, but a new issue popped out. The new issue is that I can no longer see the connected device on my scanResult. It only displays the disconnected devices. I still want to moniter my connected device. How can I acheive this?

Divyesh Boda Divyesh Boda · Accepted Answer · 2016-08-03T06:40:51

Use this class to start automatic to new BLE Devices.

BLEScanner Services

public class BLEScanner extends Service {
    private BluetoothAdapter mBluetoothAdapter;
    private ArrayList<BluetoothDevice> mLeDevices;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        mLeDevices = new ArrayList<BluetoothDevice>();
        if (getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
            BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
            mBluetoothAdapter = bluetoothManager.getAdapter();
        }
        startLeScan();
        return Service.START_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    private void startLeScan() {
        scanLeDevice(true);
    }

    private void stopLeScan() {
        scanLeDevice(false);
    }

    private void scanLeDevice(boolean enable) {
        if (enable) {
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        }
    }

    private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {

        @Override
        public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
            if (!mLeDevices.contains(device)) {
                mLeDevices.add(device);
                connectToDevice(device);
            }
        }
    };

    private void connectToDevice(final BluetoothDevice device) {
        if (device != null) {
            Log.i("Tag", "Name: " + device.getAddress() + " Connecting");
            if (device.getName() != null)
                device.connectGatt(this.getApplicationContext(), false, new BluetoothCallBack(this.getApplicationContext(), BLEScanner.this));
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        stopLeScan();
        mLeDevices.clear();
    }

    public void removeDevice(BluetoothDevice mDevice) {
        try {
            if (mLeDevices != null && mLeDevices.size() > 0)
                mLeDevices.remove(mDevice);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Now Callback Class to check BLE Device Connect or not

public class BluetoothCallBack extends BluetoothGattCallback {
    private BLEScanner mServiceObject;

    public BluetoothCallBack(Context mContext, BLEScanner mServiceObject) {
        this.mServiceObject = mServiceObject;
    }

    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        if (newState == BluetoothProfile.STATE_CONNECTED) {
            Log.i("Tag", "CONNECTED DEVICE: " + gatt.getDevice().getAddress());
            gatt.discoverServices();
        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
            Log.e("Tag", "DISCONNECTED DEVICE: " + gatt.getDevice().getAddress());
            gatt.disconnect();
            gatt.close();
            mServiceObject.removeDevice(gatt.getDevice());
        }
    }
}

Android BLE startLeScan scan for already connected device

1 Answers