geotools合并Geometry

public static Geometry unionFeatureCollectionToGeometry(SimpleFeatureCollection collection) {
    SimpleFeatureIterator features = collection.features();
    Geometry geometryUnion = null;
    while (features.hasNext()) {
        SimpleFeature next = features.next();
        Geometry geometry = (Geometry) next.getDefaultGeometry();

        if (geometryUnion == null) {
            geometryUnion = geometry;
        } else {
            geometryUnion = geometryUnion.union(geometry);
        }
    }
    return geometryUnion;
}