使用Maps API v2以编程方式初始化MapFragment

Question

我查看了演示示例代码，发现他们使用的解决方案是在oncreate()中初始化MapFragment，并在调用oncreateView()之后，在oncreame()中获取对GoogleMap的引用。

我需要在MapFragment初始化后立即获得对GoogleMap的引用，因为我希望用户能够用按钮显示或隐藏地图。我知道一个可能的解决方案是像上面所说的那样在开始时创建地图，然后设置它的可见性消失，但我希望地图默认关闭，这样如果用户没有明确要求，它就不会占用用户的带宽。

我尝试使用MapsInitializer，但也不起作用。我有点卡住了。有什么想法吗？以下是我到目前为止的测试代码：

public class ParadaInfoFragment extends BaseDBFragment {
// BaseDBFragment is just a SherlockFragment with custom utility methods.

private static final String MAP_FRAGMENT_TAG = "map";
private GoogleMap mMap;
private SupportMapFragment mMapFragment;
private TextView mToggleMapa;
private boolean isMapVisible = false;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_parada_info, container, false);
    mToggleMapa = (TextView) v.findViewById(R.id.parada_info_map_button);
    return v;
}

@Override
public void onStart() {
    super.onStart();
    mToggleMapa.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (!isMapVisible) {
                openMap();
            } else {
                closeMap();
            }
            isMapVisible = !isMapVisible;
        }
    });
}

private void openMap() {
    // Creates initial configuration for the map
    GoogleMapOptions options = new GoogleMapOptions().camera(CameraPosition.fromLatLngZoom(new LatLng(37.4005502611301, -5.98233461380005), 16))
            .compassEnabled(false).mapType(GoogleMap.MAP_TYPE_NORMAL).rotateGesturesEnabled(false).scrollGesturesEnabled(false).tiltGesturesEnabled(false)
            .zoomControlsEnabled(false).zoomGesturesEnabled(false);

    // Modified from the sample code:
    // It isn't possible to set a fragment's id programmatically so we set a
    // tag instead and search for it using that.
    mMapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentByTag(MAP_FRAGMENT_TAG);

    // We only create a fragment if it doesn't already exist.
    if (mMapFragment == null) {
        // To programmatically add the map, we first create a
        // SupportMapFragment.
        mMapFragment = SupportMapFragment.newInstance(options);
        // Then we add it using a FragmentTransaction.
        FragmentTransaction fragmentTransaction = getChildFragmentManager().beginTransaction();
        fragmentTransaction.add(R.id.parada_info_map_container, mMapFragment, MAP_FRAGMENT_TAG);
        fragmentTransaction.commit();
    }
    // We can't be guaranteed that the map is available because Google Play
    // services might not be available.
    setUpMapIfNeeded(); //XXX Here, getMap() returns null so  the Marker can't be added
    // The map is shown with the previous options.
}

private void closeMap() {
    FragmentTransaction fragmentTransaction = getChildFragmentManager().beginTransaction();
    fragmentTransaction.remove(mMapFragment);
    fragmentTransaction.commit();
}

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 = mMapFragment.getMap();
        // Check if we were successful in obtaining the map.
        if (mMap != null) {
            mMap.addMarker(new MarkerOptions().position(new LatLng(37.4005502611301, -5.98233461380005)).title("Marker"));
        }
    }
}
}

Answer 1

好的AnderWebs在Google+中给了我一个答案，但他太懒了....emm忙着在这里再写一次，所以这里是简短的版本：扩展MapFragment类并重写OnCreateView()方法。完成此方法后，我们可以获得对queGoogleMap对象的非空引用。

这是我的特殊解决方案：

public class MiniMapFragment extends SupportMapFragment {
    private LatLng mPosFija;

    public MiniMapFragment() {
        super();
    }

    public static MiniMapFragment newInstance(LatLng posicion){
        MiniMapFragment frag = new MiniMapFragment();
        frag.mPosFija = posicion;
        return frag;
    }

    @Override
    public View onCreateView(LayoutInflater arg0, ViewGroup arg1, Bundle arg2) {
        View v = super.onCreateView(arg0, arg1, arg2);
        initMap();
        return v;
    }

    private void initMap(){
        UiSettings settings = getMap().getUiSettings();
        settings.setAllGesturesEnabled(false);
        settings.setMyLocationButtonEnabled(false);

        getMap().moveCamera(CameraUpdateFactory.newLatLngZoom(mPosFija,16));
        getMap().addMarker(new MarkerOptions().position(mPosFija).icon(BitmapDescriptorFactory.fromResource(R.drawable.marker)));
    }
}

在前面的片段类中

mMapFragment = MiniMapFragment.newInstance(new LatLng(37.4005502611301, -5.98233461380005));