1

我正在尝试创建一个 abstract AsyncTask，制作一个加载器，并提供一些额外的功能。

public abstract class AbstractLoader <Params, Progress, Result> extends AsyncTask <Params, Progress, Result> {
private boolean ready;
protected Context context;
protected Application application;

public AbstractLoader (Context context, Application application) {
    this.context = context;
    this.application = application;
}

public boolean isReady() {
    return ready; 
}

protected void setReady(boolean ready) {
    this.ready = ready;
}

我从中创建了很多子类，它们部分工作，doInBackground(params)执行，但onPreExecute()不执行。唯一执行的方法是抽象类之一。

这是子类：

public class GPSLoader extends AbstractLoader<Void, Void, Integer> {

private Location location;
private LocationRestaurante[] locations;
private float[] distancias;
private float distanciaMinima;

private int idCentroComercial;

final String TAG = getClass().getCanonicalName(); 

public GPSLoader(Context context, Application application) {
    super(context, application);
    distanciaMinima = 100;

    LocationManager locationManager = (LocationManager) context
            .getSystemService(Context.LOCATION_SERVICE);

    QuickOrderLocationListener locationListener = new QuickOrderLocationListener(
            this);

    try {
        locationManager.requestLocationUpdates(
                LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);
    } catch (Exception e) {
        Log.d(TAG, e.getMessage());
    }
    Log.d(TAG, locationManager.toString());
}

@Override
protected void onPreExecute () {
    Log.d (TAG, "onPreExecute");
}

@Override
protected Integer doInBackground(Void... params) {
    synchronized (this) {
        while (location == null) {
            try {
                wait(20);
            } catch (InterruptedException e) {
                Log.d(TAG, e.toString());
            }
        }
    }

    locations = obtenerLocationsFijas();

    for (int i = 0; i < locations.length; i++) {
        float distancia = calcularPosicion(location, locations[i])[0];
        if (distancia < 100) {
            return new Integer(locations[i].getId());
        }
    }
    Log.d(TAG, "termina el gps loader");
    return null;
}

@Override
protected void onPostExecute(Integer result) {
    setReady(true);
}

public int getIdCentroComercial() {
    return idCentroComercial;
}

private float[] calcularPosicion(Location loc, Location baseLoc) {
    float[] results = null;
    Location.distanceBetween(loc.getLatitude(), loc.getLongitude(),
            baseLoc.getLatitude(), baseLoc.getLongitude(), results);
    return results;
}

private LocationRestaurante[] obtenerLocationsFijas() {
    return null;
}

private class QuickOrderLocationListener implements LocationListener {

    private GPSLoader gpsLoader;

    public QuickOrderLocationListener(GPSLoader gpsLoader) {
        this.gpsLoader = gpsLoader;
    }

    public void onLocationChanged(Location location) {
        gpsLoader.location = location;
    }

    public void onStatusChanged(String provider, int status, Bundle extras) {
    }

    public void onProviderEnabled(String provider) {
    }

    public void onProviderDisabled(String provider) {
    }
}

private class LocationRestaurante extends Location {
    private int id;

    public LocationRestaurante(String s) {
        super(s);
    }

    public int getId() {
        return id;
    }

}

}

我在这里调用方法：

private synchronized int getPosition() {
    gpsLoader.doInBackground();
    while (gpsLoader.isReady() == false) {
        try {
            wait(20);
        } catch (InterruptedException e) {
            Log.d(TAG, e.toString());
        }
    }

    int idCentroComercial = gpsLoader.getIdCentroComercial();
    return idCentroComercial;
}

onPostExecute也不执行。谢谢

4

1 回答 1

0

从gpsLoader.doInBackground();call 更改为gpsLoader.execute(null)asdoInBackground()不应手动调用。

于 2012-07-21T02:50:07.313 回答