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我正在学习使用 android 开发并尝试它，我想制作一个“接近警报”。当我接近某个点时，我需要敲响警报。

首先我做了一个循环来计算点和我们位置之间的距离，当它小于一个距离时，响警报。

没关系，但是...从逻辑上讲，当您发出警报时，您可以播放其他应用程序，所以我的发生了什么？

我需要使用 onPaused() 方法吗？也许创建一个线程？我迷失在这一刻，有人知道该怎么做吗？o 给我一些建议？

谢谢 =)

这是我的代码......现在使用 asyncTask，显然不起作用，一些帮助？

公共类 RunActivity 扩展 MapActivity {

private MapView map;
private MapController mapControl;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_run);

    this.map = (MapView)findViewById(R.id.map);
    this.map.setBuiltInZoomControls(true);       

    this.mapControl = map.getController();

    GeoPoint centro = new GeoPoint((int)(40.463667 * 1E6), (int)(-3.749220 * 1E6));
    this.mapControl.setCenter(centro);
    this.mapControl.setZoom(10);

    List<Overlay> capas = this.map.getOverlays();
    MyLocationOverlay mOverlayLocation = new MyLocationOverlay(this, this.map);

    mOverlayLocation.enableMyLocation();
    mOverlayLocation.enableCompass();

    capas.add(mOverlayLocation);

    this.map.postInvalidate();

    MiTareaAsincrona Ejemplo = new MiTareaAsincrona();
    Ejemplo.execute(RunActivity.this);
}

@Override
protected boolean isRouteDisplayed() {
    return false;
}


class MiTareaAsincrona extends AsyncTask<Context, Double, Boolean> {

    private boolean finish = false;
    private double target_lat;
    private double target_lon;

    protected void onPreExecute() {

        Bundle Datos = getIntent().getBundleExtra("Datos");
        this.target_lat = Datos.getInt("LATITUD");
        this.target_lon = Datos.getInt("LONGITUD");

    }

    protected Boolean doInBackground(Context... context) {      

        LocationManager manager = (LocationManager)context[0].getSystemService(Context.LOCATION_SERVICE);
        LocationListener listener = new LocationListener() {

            double actual_lat;
            double actual_lon;
            Bundle Datos = getIntent().getBundleExtra("Datos");

            public void onStatusChanged(String provider, int status, Bundle extras) {
                // TODO Auto-generated method stub

            }

            public void onProviderEnabled(String provider) {
                // TODO Auto-generated method stub

            }

            public void onProviderDisabled(String provider) {
                // TODO Auto-generated method stub

            }

            public void onLocationChanged(Location location) {
                actual_lat = location.getLatitude()*1E6;
                actual_lon = location.getLongitude()*1E6;

                if (distance(actual_lat, actual_lon, target_lat, target_lon) < Datos.getInt("DISTANCIA")) {
                    finish = true;
                }

            }
        };

        manager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, listener);
        return finish;
    }

    protected void onProgressUpdate() { }

    protected void onPostExecute(Boolean result) {
        if (finish) {
            Log.v("OJU", "MIARMA");
        }
    }

    /*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
    /*::  This function converts decimal degrees to radians             :*/
    /*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
    private double distance(double lat1, double lon1, double lat2, double lon2) {
      double theta = lon1 - lon2;
      double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2)) + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.cos(deg2rad(theta));
      dist = Math.acos(dist);
      dist = rad2deg(dist);
      dist = dist * 60 * 1.1515 * 1.609344 * 1000; // en metros

      return (dist);
    }

    /*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
    /*::  This function converts decimal degrees to radians             :*/
    /*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
    private double deg2rad(double deg) {
      return (deg * Math.PI / 180.0);
    }

    /*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
    /*::  This function converts radians to decimal degrees             :*/
    /*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
    private double rad2deg(double rad) {
      return (rad * 180.0 / Math.PI);
    }       

}

}

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