我正在尝试获取用户的当前位置并在MAP上显示标记。这是我的代码
public class MapsActivity extends AppCompatActivity implements LocationListener, OnMapReadyCallback {
private GoogleMap mMap;
LocationManager locationManager;
String provider;
Location mLocation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
provider = locationManager.getBestProvider(new Criteria(), false);
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
mLocation=locationManager.getLastKnownLocation(provider);
if (mLocation != null) {
Log.i("Location Status: ", "Location Found");
} else if (mLocation == null) {
Log.i("Location Status: ", "Location Not Found");
}
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
if(mLocation!=null) {
try {
Double lat = mLocation.getLatitude();
Double lng = mLocation.getLongitude();
mMap.addMarker(new MarkerOptions().position(new LatLng(lat, lng)).title("My Location"));
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(lat, lng), 12));
} catch (Exception ex) {
Log.e("Location Error:","Exception was "+ex);
}
}
}
@Override
protected void onResume() {
super.onResume();
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
locationManager.requestLocationUpdates(provider, 400, 1, this);
}
@Override
public void onLocationChanged(Location location) {
mMap.addMarker(new MarkerOptions().position(new LatLng(location.getLatitude(), location.getLongitude())).title("My Location"));
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 12));
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(getApplicationContext(),"Please enable your location",Toast.LENGTH_LONG).show();
}
@Override
protected void onPause() {
super.onPause();
locationManager.removeUpdates(this);
}
}
现在，问题在于我大部分时间都没有获得任何位置，地图显示时没有任何标记，并且在日志中显示“位置状态：未找到位置”，如果位置是，则设置为显示空值。 我试图重建并再次运行。现在，在一台设备上检测到该位置，但它在其他设备上显示相同的笨拙输出。我希望每次都能使用它，但它的表现很奇怪，因为相同的代码在同一设备上使用相同的设置在不同的时间显示两种不同的行为。 附：设备上启用了位置。 任何形式的帮助或提示将不胜感激。谢谢！
答案 0 :(得分：2)
试试我编码的代码
null mLocation 的原因
location GPS_PROVIDER
这是我的代码
public class MapsActivity extends FragmentActivity implements LocationListener, OnMapReadyCallback {
private GoogleMap mMap;
LocationManager locationManager;
Location mLocation;
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 1; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60; // 1 minute
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
locationManager = (LocationManager) this
.getSystemService(LOCATION_SERVICE);
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
isGPSEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (isGPSEnabled) {
mLocation = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (mLocation == null) {
mLocation = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
}
}
if (locationManager != null) {
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
if (mLocation != null) {
Log.e("Location Status: ", "Location Found");
} else {
Log.e("Location Status: ", "Location Not Found");
}
}
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
/*// Add a marker in Sydney and move the camera
LatLng sydney = new LatLng(-34, 151);
mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));*/
if (mLocation != null) {
try {
Double lat = mLocation.getLatitude();
Double lng = mLocation.getLongitude();
mMap.addMarker(new MarkerOptions().position(new LatLng(lat, lng)).title("My Location"));
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(lat, lng), 12.5f));
} catch (Exception ex) {
Log.e("Location Error:", "Exception was " + ex);
}
}
}
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
Toast.makeText(getApplicationContext(), "enable your location", Toast.LENGTH_LONG).show();
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(getApplicationContext(), "Please enable your location", Toast.LENGTH_LONG).show();
}
@Override
protected void onPause() {
super.onPause();
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
locationManager.removeUpdates(this);
}
}