后台服务进入休眠状态

Question

我想将传感器数据保存在文本文件中。但是我的服务只能保存数据几分钟然后停止。我添加了 WakeLock，但几分钟后它没有将传感器数据保存到文件中。 activity 和服务 class 是-

MainActivity.Class

public class MainActivity extends AppCompatActivity {

private MyService mBoundService;
boolean mIsBound;

private ServiceConnection mConnection = new ServiceConnection() {
    public void onServiceConnected(ComponentName className, IBinder service) {
        mBoundService = ((MyService.LocalBinder)service).getService();
    }

    public void onServiceDisconnected(ComponentName className) {
        mBoundService = null;
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Fabric.with(this, new Crashlytics());
    setContentView(R.layout.activity_main);

    ActivityCompat.requestPermissions(this,
            new String[]{Manifest.permission.READ_EXTERNAL_STORAGE,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE
            },
            10);
    bindService(new Intent(this,  MyService.class), mConnection, Context.BIND_AUTO_CREATE);
    mIsBound = true;
}
}

MyService.class

public class MyService extends Service implements SensorEventListener{
SensorManager mSensorManager;
Sensor mAccelerometer;
PowerManager.WakeLock cpuWakeLock;


public class LocalBinder extends Binder{
    MyService getService(){
        return MyService.this;
    }
}

private final IBinder mBinder = new LocalBinder();

private void registerListener() {
    mSensorManager.registerListener(this,
            mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
            SensorManager.SENSOR_DELAY_NORMAL);
}

private void unregisterListener() {
    mSensorManager.unregisterListener(this);
}

    public BroadcastReceiver mReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i(TAG, "onReceive("+intent+")");

        if (!intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
            return;
        }

        Runnable runnable = new Runnable() {
            public void run() {
                Log.i(TAG, "Runnable executing.");
                unregisterListener();
                registerListener();
            }
        };

        new Handler().postDelayed(runnable, 500);
    }
};

@Override
public void onCreate() {
    super.onCreate();
    mSensorManager=(SensorManager)getSystemService(SENSOR_SERVICE);
    mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    PowerManager pm= (PowerManager)  getApplicationContext().getSystemService(getApplicationContext().POWER_SERVICE);
    cpuWakeLock   = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, TAG);
    unregisterListener();
    registerListener();
    registerReceiver(mReceiver, new IntentFilter(Intent.ACTION_SCREEN_OFF));
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();
    registerListener();
    cpuWakeLock.acquire();

    return Service.START_STICKY;
}

@Override
public void onSensorChanged(SensorEvent sensorEvent) {
    String entryAcc = System.currentTimeMillis() + ", " + sensorEvent.values[0] + "," + sensorEvent.values[1] + ", " + sensorEvent.values[2] + "\n";
    Log.e("String", "value" + entryAcc);

    String dataPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyWear_Data/";
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy_MM_dd_HH_mm");
    Date now = new Date();
    String fileName = "acc_" + formatter.format(now) + ".txt";
    writeToPath(fileName, entryAcc, dataPath);

}

@Override
public void onAccuracyChanged(Sensor sensor, int i) {

}

private String writeToPath(String fileName, String data, String path) {
    FileOutputStream fos = null;
    try {
        File dir = new File(path);
        if (!dir.exists()) {
            dir.mkdirs();
        }
        File myFile = new File(dir, fileName);
        fos = new FileOutputStream(myFile, true);
        fos.write(data.getBytes());
        fos.close();
        Log.e("WriteToFile", "filename : " + fileName);
        return myFile.getPath();
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
}
}

我也在清单文件中添加了唤醒锁。我如何运行服务直到我需要并将传感器数据保存到文件？我正在为支持 android 4.2.2.

的 android 手表构建应用程序

Answer 1

由于最近的更改 android 将在一段时间后让每个服务进入休眠状态以节省电量。确保服务运行的唯一方法是使其运行具有某种前景 UI。将以下内容添加到您的服务中。

public static final int NOTIFICATION_ID = 1337;

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    runAsForeground();
    return START_NOT_STICKY;
}

private void runAsForeground() {
    Intent notificationIntent = new Intent(this, MyService.class);
    PendingIntent pendingIntent = PendingIntent.getService(this, 0,
            notificationIntent, 0);

    Notification notification = new NotificationCompat.Builder(this)
            .setOngoing(true)
            .setSmallIcon(R.drawable.your_icon_here)
            .setContentTitle("Service title here")
            .setColor(ContextCompat.getColor(this, R.color.white))
            .setContentIntent(pendingIntent)
            .build();

    startForeground(NOTIFICATION_ID, notification);
}

通过添加通知，服务将具有 UI，这将使其在 OS 之前具有更高的优先级。这意味着它只会在极少数情况下被杀死。

后台服务进入休眠状态

Background service going to sleep

service

android

background-service

android-sensors