请教老大们关于取得对象扩展数据引起的CAD崩溃

cheng5276 · 发表于 2014-9-12 17:32:00

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Autodesk..Runtime;
using Autodesk.AutoCAD.EditorInput;
using System.Windows.Forms;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.ApplicationServices;
using Application = Autodesk.AutoCAD.ApplicationServices.Application;
using Document = Autodesk.AutoCAD.ApplicationServices.Document;
[assembly: CommandClass(typeof(Cheng5276_CAD.Class1))]
namespace Cheng5276_CAD
{
public class Class1
{
      public void doc_ImpliedSelectionChanged(object sender, EventArgs e)
      {
         Autodesk.AutoCAD.EditorInput.Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
         PromptSelectionResult pkf = ed.SelectImplied();
         if (pkf.Status != PromptStatus.OK)
         { //取消选择状态
            return;
         }
         else
         { //对象选择状态
ObjectId[] objIds = pkf.Value.GetObjectIds();
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Transaction trans = doc.TransactionManager.StartTransaction();
            foreach (ObjectId objId  in objIds)
            {

                  try
                  {
                     DBObject obj = trans.GetObject(objId, OpenMode.ForRead);
                     ResultBuffer rb = obj.XData;
                     if (rb != null)
                     {
                        foreach (TypedValue tv in rb)
                        {
                              if (tv.TypeCode == 1000)
                              {
                                 string zg_t = tv.Value.ToString();
                                 break;
                              }
                        }
                        rb.Dispose();
                     }
                     trans.Commit();
                     obj.Dispose();
                  }
                  catch { }
            }
            doc.Dispose();
            trans.Dispose();
         }
      }
      [CommandMethod("FF")]
      public void Initialize()
      {
         Document acDoc = Application.DocumentManager.MdiActiveDocument;
         acDoc.ImpliedSelectionChanged += new EventHandler(doc_ImpliedSelectionChanged); //定义对象选择事件
   }
}
}
NET加载后，执行FF启用事件。
但是只要选择对象后，随便干什么，都会引起CAD崩溃，实在不明原因，请老大们指点