如何在机器人中以编程方式启用/禁用蓝牙

我想通过程序启用/禁用蓝牙。我有以下代码。

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

但是这个代码在 SDK 1.5中不能工作。我怎样才能让它工作呢？

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最佳答案

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/

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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"/>
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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.

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

 public void enableBT(){
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(){
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(){
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"/>
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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"/>
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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();
}
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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"/>
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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" />
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Updated for Android 12:

AndroidManifest.xml -

<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()

For Android 12 and above, BLUETOOTH and BLUETOOTH_ADMIN permissions are not necessary to retrieve the current state or toggle it, unless targeting lower APIs.


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