Android低功耗蓝牙（BLE）断开/重新连接

Question

The app activity displays list of available BLE devices and then connects with selected (I see notifications etc). The code:

private static BluetoothAdapter mAdapter=null;
if(mAdapter == null);
mAdapter = BluetoothAdapter.getDefaultAdapter();
mAdapter.startLeScan((BluetoothAdapter.LeScanCallback)mContext);

It gives entry of one device (as expected). However, I cannot properly disconnect. Connection seams to remain when I close the app. The led indicating connection stays ON and on next run of the app the list of available devices is emply - to disconnect I had to restart device or phone.

I've tried System. exit(0) System. exit(0) and private static BluetoothGatt mGatt; mGatt.disconnect(); private static BluetoothGatt mGatt; mGatt.disconnect(); and in Android Device Monitor stoping app instance (was there after BACK buttons from main activity, by the way - why it could be there - unregistered broadcast receiver?). Still led of the device is ON and on next app start the list of available devices is empty (and no messages displayed on screen - notifications etc).

How to reset BLE connection properly? If more app code is needed I will add it.

Answer 1

It's not entirely clear from your description what is happening. What notifications do you see? How are you building and managing your device list? Under what conditions should the LED light turn on on your device?

Regardless of this, almost certainly you should be calling mGatt.close() in your onDestroy() or onPause() if you aren't calling it before.

Whether pressing the back button finishes the app depends on how it is set up and won't necessarily mean there is some resource that hasn't been released but it's something worth checking. It's more likely to be a Service that has been left running than an unregistered broadcast receiver which I think gets handled by the system (this doesn't mean you shouldn't deregister your receivers).

Answer 2

Disconnecting has nothing to do with setting your BluetoothAdapter to null.

To disconnect from a device you have to call mGatt.close()

If you want to turn bluetooth off after that call mAdapter.disable()