安卓地图API V2中是否有类似于onFirstFix方法的功能？

Question

我可以通过使用setMyLocationEnabled来在新的Maps API中启用myLocation视图。

在第一个版本的API中，有一种方法runOnFirstFix，它使我能够在找到位置后将地图动画移动到用户位置。但是在API版本2中，我找不到类似的监听器或位置。

是否有解决方案可以在用户定位后执行某个操作？

- Janusz

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嗨Janusz - 我的回答有问题吗？如果是，请告诉我，我会更新它，否则请接受。 - DiscDev

Answer 1

Google Maps Android API V2具有LocationSource。根据文档:

“GoogleMap对象具有内置的位置提供程序，用于其我的位置图层，但可以用实现此接口的另一个位置提供程序替换它。”

您需要与LocationSource.OnLocationChangedListener一起使用它。

更新

弄清楚了。如果您想要类似于runOnFirstFix的东西，则以下是等待用户位置可用的基本示例，然后将地图动画显示在其位置中心。

public class MyLocationMapFragmentActivity extends FragmentActivity implements LocationListener, LocationSource
{
/**
 * Note that this may be null if the Google Play services APK is not available.
 */
private GoogleMap mMap;

private OnLocationChangedListener mListener;
private LocationManager locationManager;

private Context mContext;

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

    setContentView(R.layout.basic_map);

    this.mContext = this;

    locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

    //You may want to pass a different provider in as the first arg here
    //depending on the location accuracy that you desire
    //see LocationManager.getBestProvider()
    Criteria locationCriteria = new Criteria();
    locationCriteria.setAccuracy(Criteria.ACCURACY_FINE);
    locationManager.requestLocationUpdates(locationManager.getBestProvider(locationCriteria, true), 1L, 2F, this);

    setUpMapIfNeeded();
}

@Override
public void onPause()
{
    if(locationManager != null)
    {
        locationManager.removeUpdates(this);
    }

    super.onPause();
}

@Override
public void onResume()
{
    super.onResume();

    setUpMapIfNeeded();

    if(locationManager != null)
    {
        mMap.setMyLocationEnabled(true);
    }
}


/**
 * Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
 * installed) and the map has not already been instantiated.. This will ensure that we only ever
 * call {@link #setUpMap()} once when {@link #mMap} is not null.
 * <p>
 * If it isn't installed {@link SupportMapFragment} (and
 * {@link com.google.android.gms.maps.MapView
 * MapView}) will show a prompt for the user to install/update the Google Play services APK on
 * their device.
 * <p>
 * A user can return to this Activity after following the prompt and correctly
 * installing/updating/enabling the Google Play services. Since the Activity may not have been
 * completely destroyed during this process (it is likely that it would only be stopped or
 * paused), {@link #onCreate(Bundle)} may not be called again so we should call this method in
 * {@link #onResume()} to guarantee that it will be called.
 */
private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) 
    {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.basicMap)).getMap();
        // Check if we were successful in obtaining the map.

        //This is how you register the LocationSource
        mMap.setLocationSource(this);

        if (mMap != null) 
        {
            setUpMap();
        }
    }
}

/**
 * This is where we can add markers or lines, add listeners or move the camera. In this case, we
 * just add a marker near Africa.
 * <p>
 * This should only be called once and when we are sure that {@link #mMap} is not null.
 */
private void setUpMap() 
{
    mMap.setMyLocationEnabled(true);
}

@Override
public void activate(OnLocationChangedListener listener) 
{
    mListener = listener;
}

@Override
public void deactivate() 
{
    mListener = null;
}

@Override
public void onLocationChanged(Location location) 
{
    if( mListener != null )
    {
        mListener.onLocationChanged( location );

        //Move the camera to the user's location once it's available!
        mMap.animateCamera(CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude())));
    }
}

@Override
public void onProviderDisabled(String provider) 
{
    // TODO Auto-generated method stub
    Toast.makeText(this, "provider disabled", Toast.LENGTH_SHORT).show();
}

@Override
public void onProviderEnabled(String provider) 
{
    // TODO Auto-generated method stub
    Toast.makeText(this, "provider enabled", Toast.LENGTH_SHORT).show();
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) 
{
    // TODO Auto-generated method stub
    Toast.makeText(this, "status changed", Toast.LENGTH_SHORT).show();
}
}

更新2：

如果您希望在用户的位置超出屏幕时将地图居中显示在该位置（就像旧API中的MyLocationOverlay一样），请参见this answer或这篇博客文章：Google Maps Android API V2 MyLocation LocationSource and event handling。

- DiscDev