WFS 文档
https://docs.geoserver.org/stable/en/user/services/wfs/index.html
WFS 几何查询, 要素的几何字段不是 geometry , 而是 geom !
https://my.oschina.net/u/588631/blog/884481
过滤器列表:
https://docs.geoserver.org/latest/en/user/filter/function_reference.html
WFS 增删改查: