在谷歌地图上获取当前位置的简单步骤：
1 - 创建地图活动，所以在onMap准备方法中创建LocationManager和LocationListener
2 - 在onMap准备中还要检查Android版本和用户权限 ==> 如果有权限，则提供位置更新或请求用户授权
3 - 在主类中检查权限结果（onRequestPermissionsResult）==>如果条件为真，则提供位置更新
4 - 在（onLocationChanged）方法中，我们创建LatLng变量，并从位置获取坐标，然后从mMap中（addMarker and moveCamera）为刚刚创建的变量，这样当用户移动时，我们就可以得到位置，所以我们仍然需要在onMap ready中创建新的LatLng，以便在应用程序启动时拥有用户的位置 ==>如果有权限（lastKnownLocation）。
注意:
1）不要忘记在清单中请求权限（位置和互联网）
2）不要忘记从Google APIs获取地图密钥
3）我们使用（mMap.clear）来避免每次（运行应用程序或更新位置）重复标记
编程部分：
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap mMap;
LocationManager locationManager;
LocationListener locationListener;
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
}
}
@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);
}
@SuppressLint("MissingPermission")
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
locationListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
mMap.clear();
LatLng userLocation = new LatLng(location.getLatitude(), location.getLongitude());
mMap.addMarker(new MarkerOptions().position(userLocation).title("Marker"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(userLocation));
Toast.makeText(MapsActivity.this, userLocation.toString(), Toast.LENGTH_SHORT).show();
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
};
if (Build.VERSION.SDK_INT < 23 ){
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}else if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
Location lastKnownLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
LatLng userLocation = new LatLng(lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude());
mMap.clear();
mMap.addMarker(new MarkerOptions().position(userLocation).title("Marker"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(userLocation));
Toast.makeText(MapsActivity.this, userLocation.toString(), Toast.LENGTH_SHORT).show();
} else {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
}
}
}
}
