java 怎么进行矢量切片 代码实现

Java中进行矢量切片可以使用开源地图库Mapbox来实现。Mapbox提供了一套完整的矢量切片生成工具和API，可以方便地进行矢量切片的生成和处理。以下是一个简单的Java代码示例，演示如何使用Mapbox进行矢量切片的生成：

import com.mapbox.geojson.*;
import com.mapbox.mapboxsdk.Mapbox;
import com.mapbox.mapboxsdk.maps.MapView;
import com.mapbox.mapboxsdk.maps.MapboxMap;
import com.mapbox.mapboxsdk.maps.Style;
import com.mapbox.mapboxsdk.style.layers.*;
import com.mapbox.mapboxsdk.style.sources.*;
import com.mapbox.mapboxsdk.utils.BitmapUtils;
import java.util.ArrayList;
import java.util.List;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import static com.mapbox.mapboxsdk.style.expressions.Expression.eq;
import static com.mapbox.mapboxsdk.style.expressions.Expression.get;
import static com.mapbox.mapboxsdk.style.expressions.Expression.literal;

public class VectorTileTestActivity extends AppCompatActivity implements OnMapReadyCallback {

    private MapView mapView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Mapbox.getInstance(this, "YOUR_MAPBOX_ACCESS_TOKEN");
        setContentView(R.layout.activity_vector_tile_test);
        mapView = findViewById(R.id.mapView);
        mapView.onCreate(savedInstanceState);
        mapView.getMapAsync(this);
    }

    @Override
    public void onMapReady(MapboxMap mapboxMap) {
        mapboxMap.setStyle(new Style.Builder().fromUrl("mapbox://styles/mapbox/streets-v11")
                .withSource(new VectorSource("vector-tile-source", "mapbox://mapbox.mapbox-streets-v7"))
                .withLayer(new FillLayer("vector-tile-layer", "vector-tile-source")
                        .withProperties(
                                PropertyFactory.fillColor(Color.RED),
                                PropertyFactory.fillOpacity(literal(0.5f))
                        )
                        .withFilter(eq(get("layer"), literal("water")))
                ), new Style.OnStyleLoaded() {
            @Override
            public void onStyleLoaded(@NonNull Style style) {
                // Create a list of tile coordinates to request
                List<TileCoordinate> tileCoordinates = new ArrayList<>();
                tileCoordinates.add(new TileCoordinate(0, 0, 0)); // Request the root tile

                // Create a list of vector layers to include in the tileset
                List<String> layers = new ArrayList<>();
                layers.add("water");

                // Create a request for the vector tiles
                VectorTileQuery vectorTileQuery = Mapbox.getTelemetry().getLocationComponentTelemetry().createVectorTileQuery(tileCoordinates, layers);

                // Send the request to Mapbox
                vectorTileQuery.enqueueCall(new Callback<VectorTileResponse>() {
                    @Override
                    public void onResponse(Call<VectorTileResponse> call, Response<VectorTileResponse> response) {
                        if (response.isSuccessful()) {
                            VectorTileResponse vectorTileResponse = response.body();
                            if (vectorTileResponse != null) {
                                for (Tile tile : vectorTileResponse.tiles()) {
                                    // Decode the vector tile data
                                    VectorTile vectorTile = VectorTile.fromBytes(tile.data());

                                    // Create a GeoJSON FeatureCollection from the vector tile data
                                    FeatureCollection featureCollection = vectorTile.toFeatureCollection();

                                    // Log the number of features in the FeatureCollection
                                    Log.d("VectorTileTestActivity", "Number of features: " + featureCollection.features().size());

                                    // Generate a unique tile ID for storing the tile data
                                    String tileId = tile.z() + "_" + tile.x() + "_" + tile.y();

                                    // Store the FeatureCollection data for the current tile ID
                                    byte[] tileData = featureCollection.toJson().getBytes();
                                    TileDataStorage.getInstance().storeTileData(tileId, tileData);
                                }
                            }
                        }
                    }

                    @Override
                    public void onFailure(Call<VectorTileResponse> call, Throwable t) {
                        Log.e("VectorTileTestActivity", "Failed to request vector tiles", t);
                    }
                });
            }
        });
    }

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

    @Override
    public void onPause() {
        super.onPause();
        mapView.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mapView.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        mapView.onLowMemory();
    }
}

上述代码中，首先需要在`onCreate`方法中获取Mapbox的访问令牌，并初始化MapView。在`onMapReady`回调中，创建一个新的地图样式，并添加一个矢量源和一个填充图层。然后，创建一个`VectorTileQuery`对象，指定要请求的矢量切片的坐标和图层名称。接下来，使用`enqueueCall`方法发送请求到Mapbox服务器，并在回调中处理响应。最后，将矢量切片数据存储到本地，以便在后续的地图渲染中使用。