判断Featureclass的类型
一个Featureclass可以是Shapefile Feature Class、Personal Geodatabase Feature Class、File Geodatabase Feature Class等多种选择。判断其类型可从以下接口中获得。
1.FeatureLayer的话，可以直接从IFeatureLayer2.DataSourceType 取得。
2.Featureclass的话，可以QI到IDataset.Category取得。
根据返回字符串的关键字进行相应判断，英文版和中文版后面的关键不同，中文版返回中文，如“要素类”等。
| Layer Type | Value |
|---|---|
| Personal Geodatabase | "Personal Geodatabase Feature Class" |
| SDE | "SDE Feature Class" |
| Shapefile | "Shapefile Feature Class" |
| ArcInfo or PC ArcInfo Coverage (annotation) | "Annotation Feature Class" |
| ArcInfo or PC ArcInfo Coverage (point) | "Point Feature Class" |
| ArcInfo or PC ArcInfo Coverage (line) | "Arc Feature Class" |
| ArcInfo or PC ArcInfo Coverage (polygon) | "Polygon Feature Class" |
| Edge | "StreetMap Feature Class" |
| CAD (annotation) | "CAD Annotation Feature Class" |
| CAD (point) | "CAD Point Feature Class" |
| CAD (line) | "CAD Polyline Feature Class" |
| CAD (polygon) | "CAD Polygon Feature Class" |
