纬度和经度值给出空值，0.0

Question

在我的应用程序中，我试图在登录时获取用户当前的纬度和经度值。但问题是有时我得到空值，有时甚至 0.0 作为值。我什至经历过类似的帖子堆栈溢出但无法获得解决方案。请帮助。 这是我的 GPSTracker.java 服务类

    public class GPSTracker extends Service implements LocationListener {

    private final Context mContext;

    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    // flag for GPS status
    boolean canGetLocation = false;

    Location location; // location
    double latitude; // latitude
    double longitude; // longitude

    // 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

    // Declaring a Location Manager
    protected LocationManager locationManager;

    public GPSTracker(Context context) {
        this.mContext = context;
        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;
                // First get location from Network Provider
                if (isNetworkEnabled) {
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("Network", "Network");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) {
                    if (location == null) {
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                        Log.d("GPS Enabled", "GPS Enabled");
                        if (locationManager != null) {
                            location = locationManager
                                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null) {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return location;
    }

    /**
     * Stop using GPS listener
     * Calling this function will stop using GPS in your app
     * */
    public void stopUsingGPS(){
        if(locationManager != null){
            locationManager.removeUpdates(GPSTracker.this);
        }
    }

    /**
     * Function to get latitude
     * */
    public double getLatitude(){
        if(location != null){
            latitude = location.getLatitude();
        }

        // return latitude
        return latitude;
    }

    /**
     * Function to get longitude
     * */
    public double getLongitude(){
        if(location != null){
            longitude = location.getLongitude();
        }

        // return longitude
        return longitude;
    }

    /**
     * Function to check GPS/wifi enabled
     * @return boolean
     * */
    public boolean canGetLocation() {
        return this.canGetLocation;
    }

    /**
     * Function to show settings alert dialog
     * On pressing Settings button will lauch Settings Options
     * */
    public void showSettingsAlert(){
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

        // Setting Dialog Title
        alertDialog.setTitle("GPS settings");
        alertDialog.setCancelable(false);

        // Setting Dialog Message
        alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

        // On pressing Settings button
        alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog,int which) {
                Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                mContext.startActivity(intent);
            }
        });

        // on pressing cancel button
        alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
            }
        });

        // Showing Alert Message
        alertDialog.show();
    }

    @Override
    public void onLocationChanged(Location location)
    {

    }

    @Override
    public void onProviderDisabled(String provider) {
    }

    @Override
    public void onProviderEnabled(String provider) {
    }

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

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

}

Answer 1

获取 null 或 (0.0, 0.) 坐标有多种原因。 尽管存在一个有效的 (0.0, 0.0) 坐标，但实际上它从来都不是一个有效的坐标，或者以这种方式设计来表达无效的位置。
因此，您可以放心地忽略所有 null 和 (0.0, 0.0) 位置。

阅读API如何确定一个交付的位置是否有效！ 在 iOS 中，仅当 horicontalAccuracy >= 0 时才有效。
来自 Andorid 位置文档：

"LocationManager 生成的所有位置都保证有 有效的纬度、经度和时间戳（UTC 时间和经过的时间） 自启动后实时），所有其他参数都是可选的。 "

所以你描述的情况不应该发生。 因此，只需忽略 (0,0) 个位置！

进一步修改您的应用程序：首先在初始化后您应该获取最后一个已知位置，然后使用OnLocationChanged() 获取进一步的位置更新。

Answer 2

您将在 OnLocationChanged() 方法中获取当前位置

@Override
public void onLocationChanged(Location location)
{
      double lat = location.getLatitude();
      double lon = location.getLongitude();
}

Answer 3

使用这个方法

public class DashActivity extends ActionBarActivity implements
    GooglePlayServicesClient.ConnectionCallbacks,
    GooglePlayServicesClient.OnConnectionFailedListener, LocationListener {

LatLng secondToLastLocation;
LocationClient mLocationClient;
double latitudeValue, longitudeValue;

// Milliseconds per second
private static final int MILLISECONDS_PER_SECOND = 1000;
// Update frequency in seconds
public static final int UPDATE_INTERVAL_IN_SECONDS = 5;
// Update frequency in milliseconds
private static final long UPDATE_INTERVAL =  MILLISECONDS_PER_SECOND * UPDATE_INTERVAL_IN_SECONDS;
// The fastest update frequency, in seconds
private static final int FASTEST_INTERVAL_IN_SECONDS = 1;
// A fast frequency ceiling in milliseconds
private static final long FASTEST_INTERVAL =  MILLISECONDS_PER_SECOND * FASTEST_INTERVAL_IN_SECONDS;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_dash);
    mLocationClient = new LocationClient(this, this, this);
    // Create the LocationRequest object
    mLocationRequest = LocationRequest.create();
    // Use high accuracy
    mLocationRequest.setPriority( LocationRequest.PRIORITY_HIGH_ACCURACY);
    // Set the update interval to 5 seconds
    mLocationRequest.setInterval(UPDATE_INTERVAL);
    // Set the fastest update interval to 1 second
    mLocationRequest.setFastestInterval(FASTEST_INTERVAL);

}


public double getLongitude() {
    return mLocationClient.getLastLocation().getLongitude();
}

public double getLatitude() {
    return mLocationClient.getLastLocation().getLatitude();
}


@Override
public void onConnectionFailed(ConnectionResult arg0) {
    Toast.makeText(this, "Connetion fail, Unable to detect location", Toast.LENGTH_LONG).show();
}

@Override
public void onConnected(Bundle arg0) {
    Toast.makeText(this, "Connected, dectecting location", Toast.LENGTH_LONG).show();
    mLocationClient.requestLocationUpdates(mLocationRequest, this);
    sendToServer();
}

@Override
public void onDisconnected() {
    Toast.makeText(this, "You are disconnected", Toast.LENGTH_LONG).show();
    timer.interrupt();
}

@Override
protected void onStop() {
    // Disconnecting the client invalidates it.
    mLocationClient.disconnect();
    super.onStop();
}


@Override
protected void onStart() {
    super.onStart();
    mLocationClient.connect();
}


@Override
public void onLocationChanged(Location location) {
    // assign some stuff here when location chaneges
}   

}

首先从方法getLongitude() 和getLongitude() 获取最后一个知道位置，然后当位置发生变化时，您可以从onLocationChange() 中知道位置事件检测到书面变化的速率第一组线。您需要先从设备中获取最后保存的位置，它可以离线使用