C# CAD读写扩展源码示例：添加XData功能

using System;
using System.Collections.Generic;
using System.Text;
// 用户添加引用
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.EditorInput;
using System.Collections;
[assembly: CommandClass(typeof(ClassLibrary2.Class1))]
namespace ClassLibrary2
{
    public class Class1
    {
        // 写扩展记录
        [CommandMethod("aaa")]
        public void AddXdata()
        {
            // 加扩展数据
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            ed.WriteMessage("添加扩展数据XDATA\n");
            PromptEntityOptions entOps = new PromptEntityOptions("请选择要打开的对象\n");
            PromptEntityResult entRes;
            entRes = ed.GetEntity(entOps);
            if (entRes.Status != PromptStatus.OK)
            {
                ed.WriteMessage("选择对象失败，退出");  return;
            }
            ObjectId objId = entRes.ObjectId;

            Database db = HostApplicationServices.WorkingDatabase;
            using (Transaction trans = db.TransactionManager.StartTransaction())
            {
                Entity ent = trans.GetObject(objId, OpenMode.ForWrite) as Entity ;
                ent.ColorIndex = 1;
                RegAppTable appTbl = trans.GetObject(db.RegAppTableId,OpenMode.ForWrite) as RegAppTable ;
                if (!appTbl.Has("WUAZ"))
                {
                    RegAppTableRecord appTblRcd = new RegAppTableRecord();
                    appTblRcd.Name = "WUAZ";
                    appTbl.Add(appTblRcd);
                    trans.AddNewlyCreatedDBObject(appTblRcd, true);
                }            
                ResultBuffer resBuf = new ResultBuffer();
                resBuf.Add(new TypedValue(1001, "WUAZ"));//注册程序名称
                resBuf.Add(new TypedValue(1000 , "武安状"));//姓名
                resBuf.Add(new TypedValue(1000 , "河南省地矿局测绘地理信息院"));//部门
                resBuf.Add(new TypedValue(1040, 5000.0));//薪水
                ent.XData = resBuf;
                trans.Commit();
                ed.WriteMessage("写扩展记录成功!");
            }
        }              
        // 读扩展记录
        [CommandMethod("bbb")]
        public void GETXDATA()
        {
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            ed.WriteMessage("获取扩展数据XDATA\n");
            PromptEntityOptions entOps = new PromptEntityOptions("请选择要打开的对象\n");