Android:无法在 map 上获取当前位置

Question

我有一个带有谷歌地图的应用程序，其中有一个显示 map 的 Activity 。我有一个允许我更改 map 类型的菜单，但我希望有一个选项来获取我的当前位置。

这是我的 Activity 代码:

package com.example.chiapa_mapas;

import com.google.android.gms.location.LocationListener;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMapClickListener;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.MenuInflater;
import android.view.MenuItem;

public class MainActivity extends android.support.v4.app.FragmentActivity implements OnMapClickListener, LocationListener{

    private GoogleMap mMap;
    private Context ctx;
    private LocationManager locationManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        mMap.setOnMapClickListener(this);


     // Enable LocationLayer of Google Map
        mMap.setMyLocationEnabled(true);
        // Getting LocationManager object from System Service LOCATION_SERVICE
        locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);


        }

    @Override
    public boolean onCreateOptionsMenu(android.view.Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.layout.opcoes, menu);
        return true; }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {

        case R.id.normal:
            mMap.setMapType(1);
            break;

        case R.id.satellite:
            mMap.setMapType(2);
            break;

        case R.id.terrain:
            mMap.setMapType(3);
            break;
        case R.id.hybrid:
             mMap.setMapType(4);
             break;

        case R.id.none:
            mMap.setMapType(0);
            break;

        case R.id.posicao_actual:
            //mMap.setMapType(0);
            Criteria criteria = new Criteria();
            // Getting the name of the best provider
            String provider = locationManager.getBestProvider(criteria,true);
            // Getting Current Location
            Location location = locationManager.getLastKnownLocation(provider);
            if (location != null) {
                onLocationChanged(location); 
                } 

            locationManager.requestLocationUpdates(provider, 20000, 0,(android.location.LocationListener) ctx);

            break;

        default: return super.onOptionsItemSelected(item);
        }

        return true;
    }

    @Override
    public void onMapClick(LatLng position) {
        // TODO Auto-generated method stub

        mMap.addMarker(new MarkerOptions().position(position).icon(BitmapDescriptorFactory.fromResource(R.drawable.ic_launcher)));

        //double ltt = position.latitude;
        //double lgt = position.longitude;

        //String msg = "Latitude: " + Double.toString(ltt) + " , Longitude: " + Double.toString(lgt) + "";

        //Toast toast = Toast.makeText(ctx, msg, Toast.LENGTH_SHORT);
        //toast.show();     
    }

    @Override
    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub

        // Getting latitude of the current location
        double latitude = location.getLatitude();
        // Getting longitude of the current location
        double longitude = location.getLongitude();
        // Creating a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);
        // Showing the current location in Google Map
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        // Zoom in the Google Map
        mMap.animateCamera(CameraUpdateFactory.zoomTo(15));
        // Setting latitude and longitude in the TextView

        locationManager.removeUpdates((android.location.LocationListener) this);

    }

}

有人可以帮忙吗？当我按下选项“posicao actual”(当前位置)时，它崩溃了。提前致谢恰帕

Answer 1

这对我有用:

    public void methodName(){
        LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        android.location.LocationListener locationListener = new android.location.LocationListener() {
            public void onLocationChanged(Location location) {
                //Any method here
            }
            public void onStatusChanged (String provider, int status, Bundle extras){}
            public void onProviderEnabled(String provider) {}
            public void onProviderDisabled (String provider){}
        };
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,0,0, locationListener);
    }

谢谢恰帕。