将Google地图加载到片段中

Question

大家好，我只是正在学习使用Googlemaps，我有问题。我想在片段中添加地图。我的代码是：

public class MapsLine  extends Fragment {


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

    }
   
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_maps_line, container, false);

        SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);  //use SuppoprtMapFragment for using in fragment instead of activity  MapFragment = activity   SupportMapFragment = fragment
        mapFragment.getMapAsync(new OnMapReadyCallback() {
            @Override
            public void onMapReady(GoogleMap mMap) {
                mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

                mMap.clear(); //clear old markers

                CameraPosition googlePlex = CameraPosition.builder()
                        .target(new LatLng(37.4219999,-122.0862462))
                        .zoom(10)
                        .bearing(0)
                        .tilt(45)
                        .build();

                mMap.animateCamera(CameraUpdateFactory.newCameraPosition(googlePlex), 10000, null);

                mMap.addMarker(new MarkerOptions()
                        .position(new LatLng(37.4219999, -122.0862462))
                        .title("Spider Man"));
                mMap.addMarker(new MarkerOptions()
                        .position(new LatLng(37.4629101,-122.2449094))
                        .title("Iron Man")
                        .snippet("His Talent : Plenty of money"));

                mMap.addMarker(new MarkerOptions()
                        .position(new LatLng(37.3092293,-122.1136845))
                        .title("Captain America"));
            }
        });

        return rootView;
    }

    private BitmapDescriptor bitmapDescriptorFromVector(Context context, int vectorResId) {
        Drawable vectorDrawable = ContextCompat.getDrawable(context, vectorResId);
        vectorDrawable.setBounds(0, 0, vectorDrawable.getIntrinsicWidth(), vectorDrawable.getIntrinsicHeight());
        Bitmap bitmap = Bitmap.createBitmap(vectorDrawable.getIntrinsicWidth(), vectorDrawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        vectorDrawable.draw(canvas);
        return BitmapDescriptorFactory.fromBitmap(bitmap);
    }
}

mapsline_fragment-xml是：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MapsLine">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.polygons.PolyActivity" />
</FrameLayout>

我添加到清单中：

<meta-data
            android:name="com.google.android.geo.API_KEY"
            android:value="my key" ></meta-data>

我添加到build.grabdle（livel app）： 实现'com.google.android.gms：Play-Services-Maps：18.0.2' 现在，当Mapsline片段开始时，它向我展示了一个灰色屏幕，没有向我展示Google地图，就像它无法加载地图一样。我该如何解决问题？