android - 当前位置未在 google maps api v2 for android 中正确显示

Question

我已经编写了代码来使用可用的最佳提供商检测用户的位置，但它没有显示当前位置。相反，它把我带到了前一个位置，并且标记也​​没有显示。请帮助调整它。

package com.example.mapexample;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.InfoWindowAdapter;
import com.google.android.gms.maps.GoogleMap.OnInfoWindowClickListener;
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.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

public class MainActivity extends FragmentActivity implements LocationListener {

    private GoogleMap myMap;
    private LocationManager locationManager;
    private String provider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        FragmentManager myFragmentManager = getSupportFragmentManager();
        SupportMapFragment mySupportMapFragment = (SupportMapFragment) myFragmentManager
                .findFragmentById(R.id.map);
        myMap = mySupportMapFragment.getMap();
        myMap.setMyLocationEnabled(true);
        myMap.setMyLocationEnabled(true);

        View marker = ((LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.custom_marker_layout, null);
        TextView atmText  = (TextView) marker.findViewById(R.id.num_txt);
        atmText.setText("ATM");

            // Get the location manager
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        // Define the criteria how to select the locatioin provider -> use
        // default
        Criteria criteria = new Criteria();

        provider = locationManager.getBestProvider(criteria, true);
        Location location = locationManager.getLastKnownLocation(provider);

        // Initialize the location fields
        if (location != null) {
            Toast.makeText(this,
                    "Provider " + provider + " has been selected.",
                    Toast.LENGTH_SHORT).show();

            onLocationChanged(location);
        } else {
            Toast.makeText(getApplicationContext(), "Location not available",
                    Toast.LENGTH_LONG).show();

        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case R.id.menu_legalnotices:
            String LicenseInfo = GooglePlayServicesUtil
                    .getOpenSourceSoftwareLicenseInfo(getApplicationContext());
            AlertDialog.Builder LicenseDialog = new AlertDialog.Builder(
                    MainActivity.this);
            LicenseDialog.setTitle("Legal Notices");
            LicenseDialog.setMessage(LicenseInfo);
            LicenseDialog.show();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /* Request updates at startup */
    @Override
    protected void onResume() {
        super.onResume();
        locationManager.requestLocationUpdates(provider, 0, 0, this);

    }

    /* Remove the locationlistener updates when Activity is paused */
    @Override
    protected void onPause() {
        super.onPause();
        locationManager.removeUpdates(this);
    }

    public void onLocationChanged(Location location) {

        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());;
        Toast.makeText(getApplicationContext(),
                "Location" + latLng.toString(), Toast.LENGTH_LONG).show();
        CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 17);
            myMap.animateCamera(cameraUpdate);
            locationManager.removeUpdates(this);

    }

    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

    public void onProviderEnabled(String provider) {
        Toast.makeText(this, "Enabled new provider " + provider,
                Toast.LENGTH_SHORT).show();

    }

    public void onProviderDisabled(String provider) {
        Toast.makeText(this, "Disabled provider " + provider,
                Toast.LENGTH_SHORT).show();
    }


}