C#如何实现对CAD，dwg文件的读取，把里面的数据读出来

using AutoCAD = Autodesk.AutoCAD.Interop;
using dbx = Autodesk.AutoCAD.Interop.Common;
using Autodesk.AutoCAD.Interop;
AcadApplication _AcadApp = new AutoCAD.AcadApplicationClass();
AcadDocument doc = _AcadApp.Documents.Open(@"你的文件路径", false, null);
但是只能读取到单个DWG文件，请问有人知道怎么读取到文件夹么？