是否可以使用RxJava在非主线程中调用“onSensorChanged”方法？

Question

I want to call the "onSensorChanged" method in a non-main thread using RxJava.

Here is my Sensor code.

    public class Accelerometer implements SensorEventListener {
    private Sensor linearAccelerSensor;

    static PublishSubject<SensorEvent> accelerData = PublishSubject.create();
    public static Observable<SensorEvent> getAccelerObservable(){ return accelerData; }

    public void initSensor(SensorManager sm){
        linearAccelerSensor = sm.getDefaultSensor(Sensor.TYPE_LINEAR_ACCELERATION);
        sm.registerListener(this,linearAccelerSensor,10000000);
    }


    @Override
    public void onSensorChanged(SensorEvent event) {
        if(event.sensor == linearAccelerSensor){
            Log.d("Accelerometer","Acclerometer onSensorchanged");
            Log.d("Accelerometer",Thread.currentThread().getName())
            accelerData.onNext(event);
        }
    }

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

    }
}

And This is my Service's onStartCommand code.

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    myCompositeDisposable.add(Accelerometer.getAccelerObservable()
            .observeOn(Schedulers.computation())
            .subscribeOn(Schedulers.io())
            .subscribeWith(new DisposableObserver<SensorEvent>() {
                @Override
                public void onNext(SensorEvent sensorEvent) {

                    //textViewAccel.setText(sensorEvent.toString());
                    Log.d("ServiceAccelerometer",sensorEvent.toString());

                    lAccX = sensorEvent.values[0];
                    lAccY = sensorEvent.values[1];
                    lAccZ = sensorEvent.values[2];

                    lAccX = Math.round(lAccX*100)/100.0;
                    lAccY = Math.round(lAccY*100)/100.0;
                    lAccZ = Math.round(lAccZ*100)/100.0;

                    double accel = Math.sqrt((lAccX * lAccX) + (lAccY * lAccY) + (lAccZ * lAccZ));
                    accel = Math.round(accel*100)/100.0;
                    //textViewAccel.setText(lAccX+" "+lAccY+" "+lAccZ);
                    Log.d("ServiceAccelerometer",String.valueOf(accel));


                }

                @Override
                public void onError(Throwable e) {

                }

                @Override
                public void onComplete() {

                }
            })

    );
    return START_NOT_STICKY;
}

Actually, I wanted to subscribe the onSensorChanged() method in my Service file. However, onSensorChange() method only returned void, so I need to make another method which returns the Observable(). So I made the getAccelerObservable() which returns the Observable. But in this process, there was a problem.

onSensorChanged method was called by main thread because I subscribed to the getAccelerObservable() method. However, I want to call onSensorChanged method in other thread except for mainThread. How can I correct my code?

Answer 1

OnSensorChanged can't be called on any thread but main. RxJava can't even factor into it- the framework calls that, and the framework doesn't use RxJava. Now what you can do is have onSensorChange call RxJava to push the data to another thread from the main thread. Whether that's a good idea or will just lead to thrash depends on how much work you're doing with the sensor result, and whether you need to update the UI afterwards. Doing so may just cause more delay and thrashing between threads.