JTS:如何将多边形转换为MultiLineString

Question

我有多边形形状,我想将其转换为MultiLineString.请注意,通常方向不同:使用GeometryFactory构建多边形从点,坐标,线等.我开始考虑GeometryTransformer,但很难理解那里的文档...所以我有这个:

import com.vividsolutions.jts.geom.*;
...
GeometryFactory gFactory = new GeometryFactory();
GeometryTransformer gTransform = new GeometryTransformer();
Polygon polygon = gFactory.createPolygon(someLinearRing, null);
MultiLineString mlString = polygon.TODO?

如何继续TODO？

Answer 1

该方法Polygon.getBoundary()计算多边形的边界.如果多边形没有孔(也只有一个边界),则返回LinearRing类型的对象.如果多边形有孔 - 也有多个边界 - 则返回MultiLineString类型的对象.

使用方法Polygon.getNumInteriorRing()来检查多边形是否有孔,并且需要构建多线串:

GeometryFactory gFactory = new GeometryFactory();
if (polygon.getNumInteriorRing() == 0){
  // polygon has not holes, so extract the exterior ring
  // and build a multilinestring
  return gFactory.createMultiLineString(polygon.getExteriorRing());
}

else{
  // Polygon has holes, also several boundaries. 
  // Simply run getBoundary(), it will return a multilinestring
  return polygon.getBoundary();
}