giscat-vector-pojo

基于jts,提供了一套基础gis对象(Feature Geometry properties)的定义，及其与geojson的互转。 同时定义了一套基于protobuf的二进制压缩规范ProtoFeature，提供了比wkb、geojson更高压缩率的序列化方法。

install

maven add dependency:

        <dependency>
            <groupId>org.wowtools</groupId>
            <artifactId>giscat-vector-pojo</artifactId>
            <version>1.1.1-STABLE</version>
        </dependency>

与geojson互转

geojson to FeatureCollection

        String strGeoJson = "{\"features\":[{\"geometry\":{\"coordinates\":[30,10],\"type\":\"Point\"},\"type\":\"Feature\",\"properties\":{\"id\":1}},{\"geometry\":{\"coordinates\":[[30,10],[10,30],[40,40]],\"type\":\"LineString\"},\"type\":\"Feature\",\"properties\":{\"name\":\"hello\"}}],\"type\":\"FeatureCollection\"}";
        GeometryFactory geometryFactory = new GeometryFactory();// jts GeometryFactory
        FeatureCollection featureCollection = GeoJsonFeatureConverter.fromGeoJsonFeatureCollection(strGeoJson, geometryFactory);
        for (Feature feature : featureCollection.getFeatures()) {
            System.out.println(feature.getGeometry());//POINT (30 10)
            System.out.println(feature.getProperties());//{name=hello ...}
        }

FeatureCollection to geojson

        GeoJsonObject.FeatureCollection geoJson = GeoJsonFeatureConverter.toGeoJson(featureCollection);
        System.out.println(geoJson.toGeoJsonString());

完整的示例请参阅测试用例

与 bjornharrtell 的geojson的性能比对

~	反序列化	序列化
bjornharrtell	52998.875 ± 14695.850	3284.615 ± 983.774
giscat	33918.695 ± 4993.636	2875.404 ± 242.143

JMH测试代码

与wkb互转

由于geometry对象使用了jts geometry，所以与wkb互转可以直接参考jts的示例

与protobuf互转

ProtoFeature是一套基于protobuf的二进制压缩规范，提供了比wkb、geojson更高压缩率的序列化方法。

ProtoFeature压缩规范

FeatureCollection to ProtoFeature bytes

        FeatureCollection featureCollection = new FeatureCollection();
        ArrayList<Feature> features = new ArrayList<>(2);
        for (int i = 0; i < 2; i++) {
            Feature feature = new Feature();
            feature.setGeometry(new WKTReader().read("POINT (30 10)"));
            feature.setProperties(Map.of("id",1,"name","tom"));
        }
        featureCollection.setFeatures(features);
        byte[] bytes = ProtoFeatureConverter.featureCollection2Proto(featureCollection);

ProtoFeature bytes to FeatureCollection

        byte[] bytes = xxx;
        FeatureCollection featureCollection1 = ProtoFeatureConverter.proto2featureCollection(bytes, SampleData.geometryFactory);
        for (Feature feature : featureCollection1.getFeatures()) {
        System.out.println(feature.getGeometry());//jts geometry
        System.out.println(feature.getProperties());//Map<String, Object>
        }

jts Geometry to ProtoFeature bytes

        Geometry geometry = new WKTReader().read("POINT (30 10)");
        byte[] bytes = ProtoFeatureConverter.geometry2Proto(geometry);

ProtoFeature bytes to jts Geometry

        byte[] bytes = xxx;
        Geometry geometry = ProtoFeatureConverter.proto2Geometry(bytes, SampleData.geometryFactory);

完整的示例请参阅测试用例