50

我正在尝试将 MapFragment 添加到我当前的片段中。嵌套片段的使用仅限于 FragmentTransactions，您不能在布局中使用 xml 标签。另外，我希望在用户按下按钮时将其添加到主片段中。getInstance()因此，当用户按下该按钮并将其添加到适当的位置时，我正在以编程方式创建 MapFragment 。它显示正确，到目前为止一切都很好。

问题是，在附加 MapFragment 之后，我需要获取GoogleMap 对放置 Marker的引用，但该getMap()方法返回 null （因为onCreateView()尚未调用片段）。

我查看了演示示例代码，发现他们使用的解决方案是在调用后初始化 MapFragment并onCreate()获取对 GoogleMap 的引用。onResume()onCreateView()

我需要在 MapFragment 初始化后立即获取对 GoogleMap 的引用，因为我希望用户能够使用按钮显示或隐藏地图。我知道一个可能的解决方案是如上所述在开始时创建地图，然后将其可见性设置为消失，但我希望地图默认关闭，因此如果用户没有明确询问，它不会占用用户的带宽为了它。

我尝试了MapsInitializer，但也不起作用。我有点卡住了。有任何想法吗？到目前为止，这是我的测试代码：

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"));
        }
    }
}
}

谢谢

4

4 回答 4

53

好的AnderWebs在Google+上给了我答案，但是他太懒了.... emmm 忙到这里再写，所以这里是简短的版本：扩展MapFragment类并覆盖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)));
    }
}

现在在我之前的 Fragment 课程中

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

也许它还不完美，因为显示地图时屏幕会闪烁。但不确定问题是因为这个还是其他原因。

于 2012-12-05T23:35:02.170 回答
26

谢谢，发现这很有帮助。我发布了我稍微修改过的解决方案，因为当地图准备好时告诉父片段对我来说更简洁。此方法也适用于 saveInstanceState / restoreInstanceState 循环。

public class CustomMapFragment extends SupportMapFragment {

    private static final String LOG_TAG = "CustomMapFragment";

    public CustomMapFragment() {
        super();

    }

    public static CustomMapFragment newInstance() {
        CustomMapFragment fragment = new CustomMapFragment();
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater arg0, ViewGroup arg1, Bundle arg2) {
        View v = super.onCreateView(arg0, arg1, arg2);
        Fragment fragment = getParentFragment();
        if (fragment != null && fragment instanceof OnMapReadyListener) {
            ((OnMapReadyListener) fragment).onMapReady();
        }
        return v;
    }



    /**
     * Listener interface to tell when the map is ready
     */
    public static interface OnMapReadyListener {

        void onMapReady();
    }
}

用作嵌套片段：-

public class ParentFragment extends Fragment implements OnMapReadyListener {

    ...

    mMapFragment = CustomMapFragment.newInstance();
    getChildFragmentManager().beginTransaction().replace(R.id.mapContainer, mMapFragment).commit();

    @Override
    public void onMapReady() {
        mMap = mMapFragment.getMap();
    }
    ...
}

希望它可以帮助某人。

于 2013-04-16T21:48:59.917 回答
15

这是我的解决方案，我从之前发布的代码中汲取灵感并对其进行了清理。我还添加了带有和不带有 GoogleMapOptions 参数的静态方法。

public class GoogleMapFragment extends SupportMapFragment {

    private static final String SUPPORT_MAP_BUNDLE_KEY = "MapOptions";

    public static interface OnGoogleMapFragmentListener {
        void onMapReady(GoogleMap map);
    }

    public static GoogleMapFragment newInstance() {
        return new GoogleMapFragment();
    }

    public static GoogleMapFragment newInstance(GoogleMapOptions options) {
        Bundle arguments = new Bundle();
        arguments.putParcelable(SUPPORT_MAP_BUNDLE_KEY, options);

        GoogleMapFragment fragment = new GoogleMapFragment();
        fragment.setArguments(arguments);
        return fragment;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mCallback = (OnGoogleMapFragmentListener) getActivity();
        } catch (ClassCastException e) {
            throw new ClassCastException(getActivity().getClass().getName() + " must implement OnGoogleMapFragmentListener");
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = super.onCreateView(inflater, container, savedInstanceState);
        if (mCallback != null) {
            mCallback.onMapReady(getMap());
        }
        return view;
    }

    private OnGoogleMapFragmentListener mCallback;
}

使用模式如下：

public class MyMapActivity implements OnGoogleMapFragmentListener {

    ...

    @Override
    public void onMapReady(GoogleMap map) {
        mUIGoogleMap = map;

        ...

    }

    ...

    private GoogleMap mUIGoogleMap;
}
于 2013-05-02T02:40:26.703 回答
4

无需自定义SupportMapFragment，您可以使用以下代码直接执行此操作，

FragmentManager fm = getSupportFragmentManager(); // getChildFragmentManager inside fragments.
CameraPosition cp = new CameraPosition.Builder()
                    .target(initialLatLng) // your initial co-ordinates here. like, LatLng initialLatLng
                    .zoom(zoom_level)
                    .build();
SupportMapFragment mapFragment = SupportMapFragment.newInstance(new GoogleMapOptions().camera(cp));
fm.beginTransaction().replace(R.id.rl_map, mapFragment).commit();

添加这段代码layout

<RelativeLayout
       android:id="@+id/rl_map"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent" />

这将直接加载GoogleMap，Location即initialLatLng。

于 2017-03-10T07:27:33.400 回答