如何在android中以编程方式启用/禁用蓝牙

Question

I want to enable/disable bluetooth through the program. I have the following code.

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();    
if (!mBluetoothAdapter.isEnabled()) {
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);

But this code is not working in SDK 1.5. How can I make it work?

Answer 1

this code worked for me..

//Disable bluetooth
BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();    
if (mBluetoothAdapter.isEnabled()) {
    mBluetoothAdapter.disable(); 
} 

For this to work, you must have the following permissions:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

Answer 2

Here is a bit more robust way of doing this, also handling the return values of enable()\\disable() methods:

public static boolean setBluetooth(boolean enable) {
    BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    boolean isEnabled = bluetoothAdapter.isEnabled();
    if (enable && !isEnabled) {
        return bluetoothAdapter.enable(); 
    }
    else if(!enable && isEnabled) {
        return bluetoothAdapter.disable();
    }
    // No need to change bluetooth state
    return true;
}

And add the following permissions into your manifest file:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

But remember these important points:

This is an asynchronous call: it will return immediately, and clients should listen for ACTION_STATE_CHANGED to be notified of subsequent adapter state changes. If this call returns true, then the adapter state will immediately transition from STATE_OFF to STATE_TURNING_ON, and some time later transition to either STATE_OFF or STATE_ON. If this call returns false then there was an immediate problem that will prevent the adapter from being turned on - such as Airplane mode, or the adapter is already turned on.

UPDATE:

Ok, so how to implement bluetooth listener?:

private final BroadcastReceiver mReceiver = 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:
                // Bluetooth has been turned off;
                break;
            case BluetoothAdapter.STATE_TURNING_OFF:
                // Bluetooth is turning off;
                break;
            case BluetoothAdapter.STATE_ON:
                // Bluetooth is on
                break;
            case BluetoothAdapter.STATE_TURNING_ON:
                // Bluetooth is turning on
                break;
            }
        }
    }
};

And how to register/unregister the receiver? (In your Activity class)

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // ...

    // Register for broadcasts on BluetoothAdapter state change
    IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(mReceiver, filter);
}

@Override
public void onStop() {
    super.onStop();

     // ...

    // Unregister broadcast listeners
    unregisterReceiver(mReceiver);
}

Answer 3

Android BluetoothAdapter docs say it has been available since API Level 5. API Level 5 is Android 2.0.

You can try using a backport of the Bluetooth API (have not tried it personally): http://code.google.com/p/backport-android-bluetooth/

Answer 4

To Enable the Bluetooth you could use either of the following functions:

 public void enableBT(View view){
    BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if (!mBluetoothAdapter.isEnabled()){
        Intent intentBtEnabled = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); 
        // The REQUEST_ENABLE_BT constant passed to startActivityForResult() is a locally defined integer (which must be greater than 0), that the system passes back to you in your onActivityResult() 
        // implementation as the requestCode parameter. 
        int REQUEST_ENABLE_BT = 1;
        startActivityForResult(intentBtEnabled, REQUEST_ENABLE_BT);
        }
  }

The second function is:

public void enableBT(View view){
    BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if (!mBluetoothAdapter.isEnabled()){
        mBluetoothAdapter.enable();
    }
}

The difference is that the first function makes the app ask the user a permission to turn on the Bluetooth or to deny. The second function makes the app turn on the Bluetooth directly.

To Disable the Bluetooth use the following function:

public void disableBT(View view){
    BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if (mBluetoothAdapter.isEnabled()){
        mBluetoothAdapter.disable();
    }
}

NOTE/ The first function needs only the following permission to be defined in the AndroidManifest.xml file:

<uses-permission android:name="android.permission.BLUETOOTH"/>

While, the second and third functions need the following permissions:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

Answer 5

The solution of prijin worked perfectly for me. It is just fair to mention that two additional permissions are needed:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

When these are added, enabling and disabling works flawless with the default bluetooth adapter.

Answer 6

I used the below code to disable BT when my app launches and works fine. Not sure if this the correct way to implement this as google recommends not using "bluetooth.disable();" without explicit user action to turn off Bluetooth.

    BluetoothAdapter bluetooth = BluetoothAdapter.getDefaultAdapter();
    bluetooth.disable();

I only used the below permission.

<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

Answer 7

Add the following permissions into your manifest file:

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

Enable bluetooth use this

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();    
if (!mBluetoothAdapter.isEnabled()) {
    mBluetoothAdapter.enable(); 
}else{Toast.makeText(getApplicationContext(), "Bluetooth Al-Ready Enable", Toast.LENGTH_LONG).show();}

Disable bluetooth use this

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();    
if (mBluetoothAdapter.isEnabled()) {
    mBluetoothAdapter.disable(); 
}

Answer 8

Updated for Android 12:

AndroidManifest.xml -

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT"/>

You must perform the standard permission request for BLUETOOTH_CONNECT as you would when requesting permission for storage or other "prompted" items.

Usage (Kotlin) -

val bluetoothAdapter = (getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager).adapter
if (bluetoothAdapter.isEnabled)
    bluetoothAdapter.disable()

Answer 9

try this:

//this method to check bluetooth is enable or not: true if enable, false is not enable
public static boolean isBluetoothEnabled()
    {
        BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (!mBluetoothAdapter.isEnabled()) {
            // Bluetooth is not enable :)
            return false;
        }
        else{
            return true;
        }

    }

//method to enable bluetooth
    public static void enableBluetooth(){
        BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (!mBluetoothAdapter.isEnabled()) {
            mBluetoothAdapter.enable();
        }
    }

//method to disable bluetooth
    public static void disableBluetooth(){
        BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (mBluetoothAdapter.isEnabled()) {
            mBluetoothAdapter.disable();
        }
    }

Add these permissions in manifest

<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>

Answer 10

I have made a class to handle almost all this in Kotlin using Coroutines

class ActivityResultHandler(
    private val registry: ActivityResultRegistry
) {

    private val handlers = mutableListOf<ActivityResultLauncher<*>>()

    fun unregisterHandlers() {
        handlers.forEach {
            it.unregister()
        }
    }

    suspend fun requestLocationPermission(): Boolean {
        return suspendCoroutine<Boolean> { continuation ->
            val launcher = registry.register(
                LOCATION_PERMISSION_REQUEST,
//                lifecycleOwner,
                ActivityResultContracts.RequestPermission()
            ) {
                continuation.resumeWith(Result.success(it))
            }
            handlers.add(launcher)
            launcher.launch(Manifest.permission.ACCESS_FINE_LOCATION)
        }
    }

    suspend fun requestBluetoothActivation(): Boolean {
        return suspendCoroutine<Boolean> { continuation ->
            val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)

            val launcher = registry.register(
                BLUETOOTH_ON_REQUEST,
//                lifecycleOwner,
                ActivityResultContracts.StartActivityForResult()
            ) { result ->
                continuation.resume(
                    result.resultCode == Activity.RESULT_OK
                )
            }
            handlers.add(launcher)
            launcher.launch(enableBtIntent)
        }
    }

    fun checkLocationPermission(context: Context): Boolean {
        return ContextCompat.checkSelfPermission(
            context,
            Manifest.permission.ACCESS_FINE_LOCATION
        ) == PackageManager.PERMISSION_GRANTED
    }

    private suspend fun requestLocationActivation(
        intentSenderRequest: IntentSenderRequest,
    ): Boolean {
        return suspendCoroutine { continuation ->
            val launcher = registry.register(
                LOCATION_ACTIVATION_REQUEST,
//                lifecycleOwner,
                ActivityResultContracts.StartIntentSenderForResult()
            ) {
                continuation.resume(it.resultCode == Activity.RESULT_OK)
            }
            handlers.add(launcher)
            launcher.launch(intentSenderRequest)
        }
    }


    suspend fun enableLocation(context: Context): Boolean =
        suspendCoroutine { continuation ->

            val locationSettingsRequest = LocationSettingsRequest.Builder()
//        .setNeedBle(true)
                .addLocationRequest(
                    LocationRequest.create().apply {
                        priority = LocationRequest.PRIORITY_HIGH_ACCURACY
                    }
                )
                .build()

            val client: SettingsClient = LocationServices.getSettingsClient(context)
            val task: Task<LocationSettingsResponse> =
                client.checkLocationSettings(locationSettingsRequest)

            task.addOnSuccessListener {
                continuation.resume(true)
            }
            task.addOnFailureListener { exception ->
                if (exception is ResolvableApiException &&
                    exception.statusCode == LocationSettingsStatusCodes.RESOLUTION_REQUIRED
                ) {
                    val intentSenderRequest =
                        IntentSenderRequest.Builder(exception.resolution).build()

                    CoroutineScope(continuation.context).launch {
                        val result = requestLocationActivation(intentSenderRequest)
                        continuation.resume(result)
                    }
                } else {
                    continuation.resume(false)
                }
            }
        }


    companion object {
        private const val LOCATION_PERMISSION_REQUEST = "LOCATION_REQUEST"
        private const val BLUETOOTH_ON_REQUEST = "LOCATION_REQUEST"
        private const val LOCATION_ACTIVATION_REQUEST = "LOCATION_REQUEST"
    }
}

Use it like this:

// make sure you extend AppCompatActivity
class MainActivity : AppCompatActivity() {

    private val permissionRequests = ActivityResultHandler(activityResultRegistry)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // use viewmodels and fragments instead of GlobalScope
        GlobalScope.launch {
            // turn on bluetooth
            permissionRequests.requestBluetoothActivation()
            // to be able to scan for devices you also need location permission
            // also show pop up to let users know why you need location
            // https://support.google.com/googleplay/android-developer/answer/9799150?hl=en
            permissionRequests.requestLocationPermission()
            // also you need navigation to be enabled
            permissionRequests.enableLocation(this@MainActivity)
        }
    }

    override fun onDestroy() {
        super.onDestroy()
        permissionRequests.unregisterHandlers()
    }
}

coroutines dependency in gradle

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.2'

also add this permissions to manifest

    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <uses-permission-sdk-23 android:name="android.permission.ACCESS_COARSE_LOCATION" />