/// <summary>        /// 总结：用到DocumentManager.Open(filePath)时，如果是ForWrite，就需要用到lock文档锁。        /// </summary>        [CommandMethod("T38")]  //测试文档锁        public void T38()        {            //Document doc = Application.DocumentManager.MdiActiveDocument;  //如果是MdiActiveDocument，不需要锁LockDocument。            Document doc = MyTool.MyTools.OpenDwgFile(@"E:\res\autocad\test.dwg");            Database db = doc.Database;            //Database db = new Database();            //db.ReadDwgFile(@"E:\res\autocad\test.dwg", FileShare.Read, true, null);  //这种方式打开db，不要要锁。            using(doc.LockDocument())   //这里不锁的话，ForWrite模式打开就会报错，但ForRead模式不报错。但如果是MdiActiveDocument，也不需要锁。            using (Transaction trans = db.TransactionManager.StartTransaction())            {                BlockTable bt = db.BlockTableId.GetObject(OpenMode.ForRead) as BlockTable;                BlockTableRecord modelSpace = bt[BlockTableRecord.ModelSpace].GetObject(OpenMode.ForWrite) as BlockTableRecord;                /*                ObjectId bRefId = ObjectId.Null;                foreach (ObjectId id in modelSpace)                {                    if (id.GetObject(OpenMode.ForRead) is BlockReference)                    {                        bRefId = id;                    }                    break;                }                BlockReference bRef = bRefId.GetObject(OpenMode.ForWrite) as BlockReference;                bRef.DowngradeOpen();                 * */            }        }