我正在开发一款应用，我需要在地图中显示准确且最准确的位置。我尝试使用GPS_PROVIDER，距离该位置100米。你能告诉我如何获得确切位置吗？
这是我的代码
MainActivity：
public class MainActivity extends Activity implements LocationListener
{
private GoogleMap googleMap;
LocationManager locationManager;
double lat,longit;
private final float MIN_DISTANCE = 6;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
//locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, MIN_DISTANCE, this);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,50,5,this);
//locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
GPSTracker gpsTracker = new GPSTracker(this);
if(gpsTracker.canGetLocation)
{
lat = gpsTracker.latitude;
longit = gpsTracker.longitude;
System.out.println("latitude" +lat + "longitude" +longit);
Toast.makeText(getApplicationContext(), "latitude" +lat + "longitude" +longit, Toast.LENGTH_LONG).show();
}
else
{
gpsTracker.showSettingsAlert();
}
try
{
initializeMap();
}
catch(Exception e)
{
e.printStackTrace();
}
}
private void initializeMap()
{
if(googleMap == null)
{
googleMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();
/*double latitude = 17.385044;
double longitude = 78.486671;*/
String abc = "Hello Maps";
MarkerOptions marker = new MarkerOptions().position(new LatLng(lat, longit)).title(abc);
//MarkerOptions marker = new MarkerOptions().position(new LatLng(17.426836, 78.549902)).title(abc);
googleMap.addMarker(marker);
marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_ROSE));
if(googleMap == null)
{
Toast.makeText(getApplicationContext(), "Sorry unable to create", Toast.LENGTH_LONG).show();
}
}
// TODO Auto-generated method stub
}
@Override
protected void onResume() {
super.onResume();
initializeMap();
}
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
if(location.hasAccuracy())
{
return;
}
if(location.getAccuracy()>5)
{
return;
}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
GPSTracker：
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;
double latitude;
double longitude;
//The minimum distance to change updates in metters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; //10 metters
//The minimum time beetwen 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);
updateGPSCoordinates();
}
}
//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);
updateGPSCoordinates();
}
}
}
}
}
catch (Exception e)
{
//e.printStackTrace();
Log.e("Error : Location", "Impossible to connect to LocationManager", e);
}
return location;
}
public void updateGPSCoordinates()
{
if (location != null)
{
latitude = location.getLatitude();
longitude = location.getLongitude();
}
}
/**
* 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;
}
/**
* Function to get longitude
*/
public double getLongitude()
{
if (location != null)
{
longitude = location.getLongitude();
}
return longitude;
}
/**
* Function to check GPS/wifi enabled
*/
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("LAT Long");
//Setting Dialog Message
alertDialog.setMessage("GPS Message");
//On Pressing Setting button
alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener()
{
@Override
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()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
dialog.cancel();
}
});
alertDialog.show();
}
/**
* Get list of address by latitude and longitude
* @return null or List<Address>
*/
public List<Address> getGeocoderAddress(Context context)
{
if (location != null)
{
Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);
try
{
List<Address> addresses = geocoder.getFromLocation(latitude, longitude, 1);
return addresses;
}
catch (IOException e)
{
//e.printStackTrace();
Log.e("Error : Geocoder", "Impossible to connect to Geocoder", e);
}
}
return null;
}
/**
* Try to get AddressLine
* @return null or addressLine
*/
public String getAddressLine(Context context)
{
List<Address> addresses = getGeocoderAddress(context);
if (addresses != null && addresses.size() > 0)
{
Address address = addresses.get(0);
String addressLine = address.getAddressLine(0);
return addressLine;
}
else
{
return null;
}
}
/**
* Try to get Locality
* @return null or locality
*/
public String getLocality(Context context)
{
List<Address> addresses = getGeocoderAddress(context);
if (addresses != null && addresses.size() > 0)
{
Address address = addresses.get(0);
String locality = address.getLocality();
return locality;
}
else
{
return null;
}
}
/**
* Try to get Postal Code
* @return null or postalCode
*/
public String getPostalCode(Context context)
{
List<Address> addresses = getGeocoderAddress(context);
if (addresses != null && addresses.size() > 0)
{
Address address = addresses.get(0);
String postalCode = address.getPostalCode();
return postalCode;
}
else
{
return null;
}
}
/**
* Try to get CountryName
* @return null or postalCode
*/
public String getCountryName(Context context)
{
List<Address> addresses = getGeocoderAddress(context);
if (addresses != null && addresses.size() > 0)
{
Address address = addresses.get(0);
String countryName = address.getCountryName();
return countryName;
}
else
{
return null;
}
}
@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 intent)
{
return null;
}
}
请帮帮我
提前致谢
答案 0 :(得分：0)
在实际状态下，在拥有网络位置后，您将永远无法获得GPS位置。在您的第二个条件中，location永远不会是null，因为它已由网络提供商设置。简而言之，您的应用永远不会从GPS提供商那里获取用户的位置（请参阅下面的评论）。
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);
updateGPSCoordinates();
}
}
//if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled)
{
// Location will most likely never be null here, since it was fetched first by the network provider above
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);
updateGPSCoordinates();
}
}
}
最重要的是，此代码位于错误的位置，应该使用onLocationChanged(Location location)方法，以便每次有位置更新时运行。离开那里获得初步位置可能会很有趣。我建议你将代码更改为：
//if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled)
{
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);
updateGPSCoordinates();
}
}
} else 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);
updateGPSCoordinates();
}
}
// ...
@Override
public void onLocationChanged(Location location)
{
this.location = location;
updateGPSCoordinates();
}