java - 获取 map 中的用户位置

Question

我正在尝试获取用户在 map 中的位置。我有两个页面 - 一个页面有一个“单击以显示我的位置”按钮，另一个页面在单击按钮时会显示 map 。打开应用程序时我只想要第二页。但我不知道如何纠正代码。我在这里检查了其他一些问题，但无法解决我的问题。请帮助我，因为我是初学者。

MainActivity.java

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

}

public void showMyLocation(View view) {
    startActivity(new Intent(getApplicationContext(),MapsActivity.class));
}
}

MapsActivity.java

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback{

private GoogleMap mMap;
LocationManager locationManager;
private static final int REQUEST_LOCATION_PERMISSION = 1;
Marker marker;
LocationListener locationListener;

@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) getSystemService(LOCATION_SERVICE);
    if (ActivityCompat.checkSelfPermission(this,
            Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]
                        {Manifest.permission.ACCESS_FINE_LOCATION},
                REQUEST_LOCATION_PERMISSION);
    }
    locationListener = new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            double latitude = location.getLatitude();
            double longitude = location.getLongitude();
            //get the location name from latitude and longitude
            Geocoder geocoder = new Geocoder(getApplicationContext());
            try {
                List<Address> addresses =
                        geocoder.getFromLocation(latitude, longitude, 1);
                String result = addresses.get(0).getLocality()+":";
                result += addresses.get(0).getCountryName();
                LatLng latLng = new LatLng(latitude, longitude);
                mMap.addMarker(new MarkerOptions().position(latLng).title(result));
                mMap.setMaxZoomPreference(20);
                mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 12.0f));

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

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {

        }

        @Override
        public void onProviderEnabled(String provider) {

        }

        @Override
        public void onProviderDisabled(String provider) {

        }
    };
    locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListener);
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}


/**
 * Manipulates the map once available.
 * This callback is triggered when the map is ready to be used.
 * This is where we can add markers or lines, add listeners or move the camera. In this case,
 * we just add a marker near Sydney, Australia.
 * If Google Play services is not installed on the device, the user will be prompted to install
 * it inside the SupportMapFragment. This method will only be triggered once the user has
 * installed Google Play services and returned to the app.
 */
@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));
    }
}

Answer 1

您没有在 onCreate 中调用 showMyLocation 方法。

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        showMyLocation();

    }

    //Removed the view object paramter as its not required
    public void showMyLocation() {
        startActivity(new Intent(getApplicationContext(),MapsActivity.class));
    }
}

最佳做法是，如果您与 MainActivity 没有任何关系，则将 MapsActivity 设置为启动器 Activity 。