Android 最初使用网络提供商获取纬度和经度，然后使用 GPS

Question

在我的应用程序中，我需要用户当前位置的纬度和经度值。最初我检查 GPS 坐标是否可用，如果不可用，我将使用网络提供商获取用户位置的这些经纬度值，因为获取 GPS 坐标非常耗时。一旦 GPS 坐标可用，我需要获得这些值。谷歌搜索了大约 2 天，我发现了一些有关该问题的信息，并设法构建了一些代码，如下所示。我被困住了，无法前进。

我的 Activity

public class MainActivity extends Activity {

    double x, y;

    Timer timer;
    LocationManager lm;
    boolean gps_enabled = false;
    boolean network_enabled = false;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        lm = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

        gps_enabled = lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
        network_enabled = lm
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!gps_enabled && !network_enabled) {
            Context context = getApplicationContext();
            int duration = Toast.LENGTH_SHORT;
            Toast toast = Toast.makeText(context, "nothing is enabled",
                    duration);
            toast.show();

        }

        if (gps_enabled)
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0,
                    locationListenerGps);
        if (network_enabled)
            lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0,
                    locationListenerNetwork);
        timer = new Timer();
        timer.schedule(new GetLastLocation(), 20000);

    }

    LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer.cancel();
            x = location.getLatitude();
            y = location.getLongitude();
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerNetwork);

            Context context = getApplicationContext();
            int duration = Toast.LENGTH_SHORT;
            Toast toast = Toast.makeText(context,
                    "gps enabled " + x + "\n" + y, duration);
            toast.show();
        }

        public void onProviderDisabled(String provider) {
        }

        public void onProviderEnabled(String provider) {
        }

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

    LocationListener locationListenerNetwork = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer.cancel();
            x = location.getLatitude();
            y = location.getLongitude();
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerGps);

            Context context = getApplicationContext();
            int duration = Toast.LENGTH_SHORT;
            Toast toast = Toast.makeText(context, "network enabled" + x + "\n"
                    + y, duration);
            toast.show();
        }

        public void onProviderDisabled(String provider) {
        }

        public void onProviderEnabled(String provider) {
        }

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

    class GetLastLocation extends TimerTask {
        @Override
        public void run() {
            lm.removeUpdates(locationListenerGps);
            lm.removeUpdates(locationListenerNetwork);

            Location net_loc = null, gps_loc = null;
            if (gps_enabled)
                gps_loc = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            if (network_enabled)
                net_loc = lm
                        .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

            // if there are both values use the latest one
            if (gps_loc != null && net_loc != null) {
                if (gps_loc.getTime() > net_loc.getTime()) {
                    x = gps_loc.getLatitude();
                    y = gps_loc.getLongitude();
                    Context context = getApplicationContext();
                    int duration = Toast.LENGTH_SHORT;
                    Toast toast = Toast.makeText(context, "gps lastknown " + x
                            + "\n" + y, duration);
                    toast.show();
                } else {
                    x = net_loc.getLatitude();
                    y = net_loc.getLongitude();
                    Context context = getApplicationContext();
                    int duration = Toast.LENGTH_SHORT;
                    Toast toast = Toast.makeText(context, "network lastknown "
                            + x + "\n" + y, duration);
                    toast.show();

                }

            }

            if (gps_loc != null) {
                {
                    x = gps_loc.getLatitude();
                    y = gps_loc.getLongitude();
                    Context context = getApplicationContext();
                    int duration = Toast.LENGTH_SHORT;
                    Toast toast = Toast.makeText(context, "gps lastknown " + x
                            + "\n" + y, duration);
                    toast.show();
                }

            }
            if (net_loc != null) {
                {
                    x = net_loc.getLatitude();
                    y = net_loc.getLongitude();
                    Context context = getApplicationContext();
                    int duration = Toast.LENGTH_SHORT;
                    Toast toast = Toast.makeText(context, "network lastknown "
                            + x + "\n" + y, duration);
                    toast.show();

                }
            }
            Context context = getApplicationContext();
            int duration = Toast.LENGTH_SHORT;
            Toast toast = Toast.makeText(context, "no last know avilable",
                    duration);
            toast.show();

        }
    }
}

到目前为止，使用上面的代码，我从网络提供商那里获得了经纬度值，但无法获得 GPS 坐标。我应该在上面的代码中添加或编辑什么来获取 GPS 坐标？

Answer 1

我发现 Android 开发人员指南非常有用:http://developer.android.com/guide/topics/location/strategies.html#BestEstimate

它说明了一个典型的程序流程应该是什么样子，以便使用不同的位置提供商获得最准确的用户位置。