import com.vividsolutions.jts.precision.EnhancedPrecisionOp; //导入依赖的package包/类
public List<String> getOverlay(final Geometry layer1,
		final Geometry layer2, final int op) {
	final List<String> resultLayer = new ArrayList<String>();
	Geometry geomContorno = null;

	switch (op) {
	case OverlayOp.INTERSECTION:
		geomContorno = EnhancedPrecisionOp.intersection(
				layer1.buffer(TOLERANCIA), layer2.buffer(TOLERANCIA));
		break;
	case OverlayOp.DIFFERENCE:
		geomContorno = EnhancedPrecisionOp.difference(
				layer1.buffer(TOLERANCIA), layer2.buffer(TOLERANCIA));
		break;
	case OverlayOp.SYMDIFFERENCE:
		geomContorno = EnhancedPrecisionOp.symDifference(
				layer1.buffer(TOLERANCIA), layer2.buffer(TOLERANCIA));
		break;
	default:
		break;
	}

	if (geomContorno != null) {

		if (geomContorno instanceof Polygon) {
			resultLayer.add(geomContorno.toText());
		} else if (geomContorno instanceof MultiPolygon) {

			final MultiPolygon multiPolygon = (MultiPolygon) geomContorno;
			for (int i = 0; i < multiPolygon.getNumGeometries(); i++) {
				final Polygon pol = (Polygon) multiPolygon.getGeometryN(i);
				resultLayer.add(pol.toText());
			}
		} else if (geomContorno instanceof GeometryCollection) {

			final GeometryCollection gc = (GeometryCollection) geomContorno;
			for (int i = 0; i < gc.getNumGeometries(); i++) {
				final Geometry geom = gc.getGeometryN(i);
				resultLayer.add(geom.toText());
			}
		}
	}

	return resultLayer;
}