我正在嘗試獲取用戶的位置longitude以及latitude從GPS/network哪個位置可用，我想快速獲取它，否則，如果現在無法獲取新的位置坐標，則會返回以前的位置坐標。這是我的嘗試：public class GPSTracker extends Service{    // The minimum distance to change Updates in meters    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters    // The minimum time between updates in milliseconds    private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute    private final Context mContext;    // Declaring a Location Manager    protected LocationManager locationManager;    // flag for GPS status    boolean isGPSEnabled = false;    // flag for network status    boolean isNetworkEnabled = false;    // flag for GPS status    boolean canGetLocation = false;    Location location = null; // location    double latitude; // latitude    double longitude; // longitude    myLocationLitener locationLitener;    public GPSTracker(Context context) {        this.mContext = context;        locationLitener = new myLocationLitener();        getLocation();    }    public Location getLocation() {        try {            locationManager = (LocationManager) mContext                    .getSystemService(LOCATION_SERVICE);            // getting GPS status            isGPSEnabled = locationManager                    .isProviderEnabled(LocationManager.GPS_PROVIDER);            // getting network status            isNetworkEnabled = locationManager                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);            if (!isGPSEnabled && !isNetworkEnabled) {                // no network provider is enabled            } else {                this.canGetLocation = true;                if (isNetworkEnabled) {                    locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES,locationLitener);                    Log.d("Network", "Network Enabled");                    if (locationManager != null) {                        location = locationManager我如何使用該課程？