1

我有这个代码来获取经纬度坐标。

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

Criteria criteria = new Criteria();
bestProvider = lm.getBestProvider(criteria, true);
Location location = lm.getLastKnownLocation(bestProvider);

     if (location == null){
      }else{
        geocoder = new Geocoder(this);
        try {
        setLat((double)location.getLatitude());
        setLng((double)location.getLongitude());

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

我尝试使用不同的设备。有些返回 lat 和 long 的值。有些没有。所有设备都连接到互联网并启用了 gps。你们对造成这种情况的原因有任何想法吗？谢谢！

4

3 回答 3

1

试试这个方法：你的实用程序类

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;
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 = 40; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 10000 * 60 * 1; // 10 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;
}
@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;
}
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;
}
public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 * */
public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

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

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

    // Setting Icon to Dialog
    alertDialog.setIcon(R.drawable.ic_launcher_web);

    // 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();
}
public void stopUsingGPS(){
    if(locationManager != null){
        locationManager.removeUpdates(GPSTracker.this);
    }      
}
}

从您的活动中调用

public void getLocation() {
    GPSTracker gps = new GPSTracker(this);
    if(gps.canGetLocation()){ 
        double lat = gps.getLatitude(); // returns latitude
        double lng = gps.getLongitude(); // returns longitude
        Global_reco.latitudeTmp = String.valueOf(lat);
        Global_reco.longitudeTmp = String.valueOf(lng);
    }
    if(!gps.canGetLocation())
    {
        gps.showSettingsAlert();
    }
}

它适用于所有设备......希望这有帮助

于 2013-09-05T09:43:35.043 回答
0

如果没有之前捕获的位置，那么getlastknown location不会返回任何值。所以需要实现位置监听器来捕获位置。

于 2013-09-05T09:46:27.010 回答
0

这是由于 getLastKnownLocation 可能存在也可能不存在。我建议您请求单个位置更新。另请记住，lastknownlocation 不一定准确，它可能属于 2 天前。开发指南：http: //developer.android.com/reference/android/location/LocationManager.html

关于单次更新的指南 http://androidexperinz.wordpress.com/2012/04/19/current-location-update/

于 2013-09-05T09:47:45.277 回答