获得Arcengine中图层的类型，尤其没有FeatureClass有效
IFeatureLayer2 pFeatureLayer2=pFeatureLayer as IFeatureLayer2;
this.pGeometryType = pFeatureLayer2.ShapeType;
IFeatureLayer2 pFeatureLayer2=pFeatureLayer as IFeatureLayer2;
this.pGeometryType = pFeatureLayer2.ShapeType;