如何检索Google Maps android的经度和纬度

import android.content.Context;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

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

        // 获取地理位置的经度和纬度
        double latitude = 0;
        double longitude = 0;
        String locationName = "北京市";

        Geocoder geocoder = new Geocoder(this, Locale.getDefault());
        try {
            List<Address> addresses = geocoder.getFromLocationName(locationName, 1);
            if (addresses != null && addresses.size() > 0) {
                Address address = addresses.get(0);
                latitude = address.getLatitude();
                longitude = address.getLongitude();
            }
        } catch (IOException e) {
            Log.e(TAG, "Geocoder exception: " + e.getMessage());
        }

        Log.d(TAG, "Latitude: " + latitude);
        Log.d(TAG, "Longitude: " + longitude);
    }
}