Android Broadcast Receiver bluetooth events catching
I'm trying to catch bluetooth state changes with Broadcast Receiver.
My manifest:
<uses-permission android:name="android.permission.BLUETOOTH" />
<application>
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".BluetoothBroadcastReceiver"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.bluetooth.adapter.action.STATE_CHANGED" />
<action android:name="android.bluetooth.adapter.action.CONNECTION_STATE_CHANGED" />
<action android:name="android.bluetooth.device.action.ACL_CONNECTED" />
<action android:name="android.bluetooth.device.action.ACL_DISCONNECTED" />
</intent-filter>
</receiver>
</application>
Receiver onReceive method:
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Log.d("BroadcastActions", "Action "+action+"received");
int state;
BluetoothDevice bluetoothDevice;
switch(action)
{
case BluetoothAdapter.ACTION_STATE_CHANGED:
state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1);
if (state == BluetoothAdapter.STATE_OFF)
{
Toast.makeText(context, "Bluetooth is off", Toast.LENGTH_SHORT).show();
Log.d("BroadcastActions", "Bluetooth is off");
}
else if (state == BluetoothAdapter.STATE_TURNING_OFF)
{
Toast.makeText(context, "Bluetooth is turning off", Toast.LENGTH_SHORT).show();
Log.d("BroadcastActions", "Bluetooth is turning off");
}
else if(state == BluetoothAdapter.STATE_ON)
{
Log.d("BroadcastActions", "Bluetooth is on");
}
break;
case BluetoothDevice.ACTION_ACL_CONNECTED:
bluetoothDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
Toast.makeText(context, "Connected to "+bluetoothDevice.getName(),
Toast.LENGTH_SHORT).show();
Log.d("BroadcastActions", "Connected to "+bluetoothDevice.getName());
break;
case BluetoothDevice.ACTION_ACL_DISCONNECTED:
bluetoothDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
Toast.makeText(context, "Disconnected from "+bluetoothDevice.getName(),
Toast.LENGTH_SHORT).show();
break;
}
}
I launch app then minimize it by pressing Home button. Go to settings and turn on bluetooth but nothing happens. Though I expect toast and logcat messages. What's wrong here?
Answer
In order to catch Bluetooth state changes (STATE_OFF, STATE_TURNING_ON, STATE_ON, STATE_TURNING_OFF), do this in your Activity:
First, add Bluetooth permission to your AndroidManifest file:
<uses-permission android:name="android.permission.BLUETOOTH" />
Create a BroadcastReceiver in your Activity or Service:
private final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR);
switch(state) {
case BluetoothAdapter.STATE_OFF:
..
break;
case BluetoothAdapter.STATE_TURNING_OFF:
..
break;
case BluetoothAdapter.STATE_ON:
..
break;
case BluetoothAdapter.STATE_TURNING_ON:
..
break;
}
}
}
};
Create an IntentFilter and register it with BroadcastReceiver to Activity/Service in your onCreate() method:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
IntentFilter filter1 = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, filter1);
...
}
Unregister BroadcastReceiver in your onDestroy() method:
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(mBroadcastReceiver1);
}
In order to catch changes of discoverability of device (SCAN_MODE_NONE, SCAN_MODE_CONNECTABLE, SCAN_MODE_CONNECTABLE_DISCOVERABLE), create another BroadcastReceiver and register/unregister to your Activity as I mentioned above. Only difference between those BroadcastReceiver's is first one uses BluetoothAdapter.EXTRA_STATE and the other one uses BluetoothAdapter.EXTRA_SCAN_MODE. Here is the example code for BroadcastReceiver to catch discoverability changes:
Create filter and register it in onCreate() method:
IntentFilter filter2 = new IntentFilter();
filter2.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter2.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
filter2.addAction(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
registerReceiver(mBroadcastReceiver2, filter2);
Create the BroadcastReciver in Activity/Service to catch discoverability changes:
private final BroadcastReceiver mBroadcastReceiver2 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if(action.equals(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED)) {
int mode = intent.getIntExtra(BluetoothAdapter.EXTRA_SCAN_MODE, BluetoothAdapter.ERROR);
switch(mode){
case BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE:
..
break;
case BluetoothAdapter.SCAN_MODE_CONNECTABLE:
..
break;
case BluetoothAdapter.SCAN_MODE_NONE:
..
break;
}
}
}
};
And lastly unregister it in onDestroy():
unregisterReceiver(mBroadcastReceiver2);
Note that, you don't need to add any <intent-filter> or <receiver> to your AndroidManifest file, except you need to add Bluetooth permission of course.
If you want to catch (ACTION_ACL_CONNECTED, ACTION_ACL_DISCONNECTED, ACTION_ACL_DISCONNECT_REQUESTED), now you need to add an <intent-filter> to your AndroidManifest file:
<intent-filter>
<action android:name="android.bluetooth.device.action.ACL_CONNECTED" />
<action android:name="android.bluetooth.device.action.ACL_DISCONNECTED" />
</intent-filter>
Create filter and register it in onCreate() method:
IntentFilter filter3 = new IntentFilter();
filter3.addAction(BluetoothDevice.ACTION_ACL_CONNECTED);
filter3.addAction(BluetoothDevice.ACTION_ACL_DISCONNECTED);
registerReceiver(mBroadcastReceiver3, filter3);
Then create the BroadcastReceiver in your Activity/Service:
private final BroadcastReceiver mBroadcastReceiver3 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
switch (action){
case BluetoothDevice.ACTION_ACL_CONNECTED:
..
break;
case BluetoothDevice.ACTION_ACL_DISCONNECTED:
..
break;
}
}
};
And lastly, unregister:
unregisterReceiver(mBroadcastReceiver3);
If you want to read more about state constants, this is from the documentation:
public static final String EXTRA_STATE:
Used as an int extra field in ACTION_STATE_CHANGED intents to request the current power state. Possible values are: STATE_OFF, STATE_TURNING_ON, STATE_ON, STATE_TURNING_OFF
public static final String EXTRA_SCAN_MODE:
Used as an int extra field in ACTION_SCAN_MODE_CHANGED intents to request the current scan mode. Possible values are: SCAN_MODE_NONE, SCAN_MODE_CONNECTABLE, SCAN_MODE_CONNECTABLE_DISCOVERABLE