java - 屏幕关闭时,前台服务上的 Android 蓝牙 LE 扫描仪立即停止
问题描述
我有以下 BLE 前台服务实现 -
public class BluetoothForegroundService extends Service {
private PowerManager.WakeLock wakeLock;
@Override
public void onCreate() {
super.onCreate();
PowerManager powerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK , this.getClass().getSimpleName());
wakeLock.acquire();
}
@Override
public void onDestroy() {
super.onDestroy();
wakeLock.release();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
super.onStartCommand(intent, flags, startId);
Intent notificationIntent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);
Notification notification = new NotificationCompat.Builder(this, "BLE test")
.setContentTitle("Bluetooth Service")
.setContentText("Fetching Bluetooth")
.setSmallIcon(R.drawable.ic_launcher)
.setContentIntent(pendingIntent)
.build();
startForeground(1, notification);
BluetoothScanner bluetoothScanner = BluetoothScanner.getInstance(new BluetoothScanner.OnBlePacketBuilderListener() {
@Override
public void onBleObjectsCreated(BleBeaconPacketData beaconPacketData, BleHardwarePacketData bleBroadcastPacketData) {
if (bleBroadcastPacketData == null && beaconPacketData == null) return;
Log.d("onBleObjectsCreated", "onBleObjectsCreated");
Intent intent = new Intent("action");
if (beaconPacketData != null)
intent.putExtra("BleBeaconPacketData", beaconPacketData);
if (bleBroadcastPacketData != null)
intent.putExtra("BleHardwarePacketData", bleBroadcastPacketData);
sendBroadcast(intent);
}
});
bluetoothScanner.startBluetooth();
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
public class BluetoothScanner implements BluetoothAdapter.LeScanCallback, BlePacketBuilder.BlePacketBuilderListener {
interface OnBlePacketBuilderListener{
void onBleObjectsCreated(BleBeaconPacketData beaconPacketData, BleHardwarePacketData bleBroadcastPacketData);
}
private final OnBlePacketBuilderListener listener;
private BluetoothAdapter bluetoothAdapter;
public static BluetoothScanner instance;
private BluetoothScanner(OnBlePacketBuilderListener listener) {
this.listener = listener;
}
public static BluetoothScanner getInstance(OnBlePacketBuilderListener listener) {
if (instance == null)
instance = new BluetoothScanner(listener);
return instance;
}
public void startBluetooth() {
BluetoothManager bluetoothManager = MainApplication.getPureTrackApplicationContext().getSystemService(BluetoothManager.class);
if ((bluetoothManager != null ? bluetoothManager.getAdapter() : null) == null) return;
bluetoothAdapter = bluetoothManager.getAdapter();
bluetoothAdapter.startLeScan(this);
}
public void stopBluetooth() {
if (bluetoothAdapter == null) return;
bluetoothAdapter.stopLeScan(this);
}
@Override
public void onLeScan(BluetoothDevice bluetoothDevice, int rssi, byte[] scanRecord) {
Log.d("BluetoothScanner", "New BLE - " + Arrays.toString(scanRecord));
BlePacketBuilder blePacketBuilder = new BlePacketBuilder(this);
blePacketBuilder.parseResult(bluetoothDevice, rssi, scanRecord);
}
@Override
public void onfinishedToParseResults(BleBeaconPacketData beaconPacketData, BleHardwarePacketData bleBroadcastPacketData) {
listener.onBleObjectsCreated(beaconPacketData, bleBroadcastPacketData);
}
}
在我的 MainActivity 上,我正在接收广播 -
private void getBluetoothDataFromForegroundService() {
registerReceiver(new BluetoothScannerReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (powerManager == null) return;
Log.d("onReceiveBle", "onReceiveBle");
//At this point data is handled both for UI and for network calls
}
}, new IntentFilter("action"));
}
问题是即使屏幕永远关闭,我也需要 BLE 来保持采样数据。这是一个内部产品,所以我不关心电池消耗或普通应用程序用户会担心的任何事情。我只需要永远采样 BLE 并通过网络调用相应地处理数据。
我尝试使用 WakeLock 并没有帮助。屏幕关闭时我没有获取日志,当屏幕重新打开时我没有获取日志。我缺少什么让 BLE 继续采样?
解决方案
我认为你缺少一些东西。
Android 10 权限
在 Android 10 上,您通常必须获得 ACCESS_BACKGROUND_LOCATION 才能在您的应用不可见时进行信标检测。但是,如果您将 android:foregroundServiceType="location" 添加到清单中的前台服务声明中,则可以仅在授予前台位置权限和前台服务的情况下进行扫描。有关详细信息,请参见此处。
因此,您需要ACCESS_BACKGROUND_LOCATION才能在 A10+ 屏幕关闭时获得扫描结果。
此外,在 A8 中已经引入,(您可以在此处查看),扫描功能停止前有 10 分钟的限制。因此,我建议您使用JobScheduler或Runnable设置9 分钟(或 10 分钟)计时器并重置扫描。这样您就可以获得长时间的扫描服务。这是一个例子:
mHandlerUpdate?.removeCallbacksAndMessages(null)
mHandlerUpdate?.postDelayed(object : Runnable {
override fun run() {
Log.d(BleService::class.java.simpleName, "run: in runnable handler")
scanner.stopScan(mScanCallback)
scanner.startScan(
filters,
settings,
mScanCallback
)
mHandlerUpdate?.postDelayed(this, 60000)
}
}, 60000)
上面的处理程序每 60 秒重置一次扫描。只是一个演示代码。您可以根据自己的需要进行修改。完成后记得删除CallbacksAndMessages。
此外,为了获得结果,必须启用位置服务。你可以在这里看到为什么。
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