Android Connecting to a GATT Server


Example

Once you have discovered a desired BluetoothDevice object, you can connect to it by using its connectGatt() method which takes as parameters a Context object, a boolean indicating whether to automatically connect to the BLE device and a BluetoothGattCallback reference where connection events and client operations results will be delivered:

 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        device.connectGatt(context, false, bluetoothGattCallback, BluetoothDevice.TRANSPORT_AUTO);
    } else {
        device.connectGatt(context, false, bluetoothGattCallback);
    }

Override onConnectionStateChange in BluetoothGattCallback to receive connection an disconnection events:

    BluetoothGattCallback bluetoothGattCallback =
        new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status,
            int newState) {
        if (newState == BluetoothProfile.STATE_CONNECTED) {
            Log.i(TAG, "Connected to GATT server.");

        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
            
            Log.i(TAG, "Disconnected from GATT server.");
        }
    }
   };