How to programmatically tell if a Bluetooth device is connected?
-
12-10-2019 - |
Pergunta
I understand how to get a list of paired devices but how can I tell if they are connected?
It must be possible since I see them listed in my phone's Bluetooth device list and it states their connection status.
Solução
Add bluetooth permission to your AndroidManifest,
<uses-permission android:name="android.permission.BLUETOOTH" />
Then use intent filters to listen to the ACTION_ACL_CONNECTED
, ACTION_ACL_DISCONNECT_REQUESTED
, and ACTION_ACL_DISCONNECTED
broadcasts:
public void onCreate() {
...
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
filter.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
this.registerReceiver(mReceiver, filter);
}
//The BroadcastReceiver that listens for bluetooth broadcasts
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
... //Device found
}
else if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
... //Device is now connected
}
else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
... //Done searching
}
else if (BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED.equals(action)) {
... //Device is about to disconnect
}
else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
... //Device has disconnected
}
}
};
A few notes:
- There is no way to retrieve a list of connected devices at application startup. The Bluetooth API does not allow you to QUERY, instead it allows you to listen to CHANGES.
- A hoaky work around to the above problem would be to retrieve the list of all known/paired devices... then trying to connect to each one (to determine if you're connected).
- Alternatively, you could have a background service watch the Bluetooth API and write the device states to disk for your application to use at a later date.
Outras dicas
In my use case I only wanted to see if a Bluetooth headset is connected for a VoIP app. The following solution worked for me:
public static boolean isBluetoothHeadsetConnected() {
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
return mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()
&& mBluetoothAdapter.getProfileConnectionState(BluetoothHeadset.HEADSET) == BluetoothHeadset.STATE_CONNECTED;
}
Of course you'll need the Bluetooth permission:
<uses-permission android:name="android.permission.BLUETOOTH" />
Big thanks to Skylarsutton for his answer. I'm posting this as a response to his, but because I'm posting code I can't reply as a comment. I already upvoted his answer so am not looking for any points. Just paying it forward.
For some reason BluetoothAdapter.ACTION_ACL_CONNECTED could not be resolved by Android Studio. Perhaps it was deprecated in Android 4.2.2? Here is a modification of his code. The registration code is the same; the receiver code differs slightly. I use this in a service which updates a Bluetooth-connected flag that other parts of the app reference.
public void onCreate() {
//...
IntentFilter filter1 = new IntentFilter(BluetoothDevice.ACTION_ACL_CONNECTED);
IntentFilter filter2 = new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECT_REQUESTED);
IntentFilter filter3 = new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECTED);
this.registerReceiver(mReceiver, filter1);
this.registerReceiver(mReceiver, filter2);
this.registerReceiver(mReceiver, filter3);
}
//The BroadcastReceiver that listens for bluetooth broadcasts
private final BroadcastReceiver BTReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_ACL_CONNECTED.equals(action)) {
//Do something if connected
Toast.makeText(getApplicationContext(), "BT Connected", Toast.LENGTH_SHORT).show();
}
else if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) {
//Do something if disconnected
Toast.makeText(getApplicationContext(), "BT Disconnected", Toast.LENGTH_SHORT).show();
}
//else if...
}
};
This code is for the headset profiles, probably it will work for other profiles too. First you need to provide profile listener (Kotlin code):
private val mProfileListener = object : BluetoothProfile.ServiceListener {
override fun onServiceConnected(profile: Int, proxy: BluetoothProfile) {
if (profile == BluetoothProfile.HEADSET)
mBluetoothHeadset = proxy as BluetoothHeadset
}
override fun onServiceDisconnected(profile: Int) {
if (profile == BluetoothProfile.HEADSET) {
mBluetoothHeadset = null
}
}
}
Then while checking bluetooth:
mBluetoothAdapter.getProfileProxy(context, mProfileListener, BluetoothProfile.HEADSET)
if (!mBluetoothAdapter.isEnabled) {
return Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
}
It takes a bit of time until onSeviceConnected is called. After that you may get the list of the connected headset devices from:
mBluetoothHeadset!!.connectedDevices
BluetoothAdapter.getDefaultAdapter().isEnabled
->
returns true when bluetooth is open
val audioManager = this.getSystemService(Context.AUDIO_SERVICE) as
AudioManager
audioManager.isBluetoothScoOn
->
returns true when device connected
I know this thread is kind of old, but I really needed to know if a device was connected right at the startup of my app, and I found the solution!
//List of Paired Devices
Set<BluetoothDevice> pairedDevices = bluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
// There are paired devices. Get the name and address of each paired device.
for (BluetoothDevice device : pairedDevices) {
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
}
}
else {
//There are no paired devices.
}
It is available right here, in Kotlin as well: https://developer.android.com/guide/topics/connectivity/bluetooth#QueryPairedDevices