/// <summary>
        /// 修改字体样式
        /// </summary>
        /// <param name="doc"></param>
        /// <param name="textStyleName">字体样式名(STANDARD)</param>
        /// <param name="cassLayersName">要改变的图层名</param>
        public void SelectFont(Document doc, string textStyleName, List<string> 
cassLayersName)
        {
            Transaction trans = null;
            DocumentLock docLock = null;
            try
            {
                trans = doc.TransactionManager.StartTransaction();
                docLock = doc.LockDocument();
                TextStyleTable st = trans.GetObject(doc.Database.TextStyleTableId, 
OpenMode.ForRead) as TextStyleTable;
                ObjectId styleID = ObjectId.Null;
                //查询是否包含样式
                if (st.Has(textStyleName))
                {
                    styleID = st[textStyleName];
                }
                else
                {
                    return;
                }
                Editor ed = doc.Editor;
                foreach (string cassLayerName in cassLayersName)
                {
                    TypedValue[] tvs = new TypedValue[]
                        {
                         new TypedValue((int)DxfCode.Operator, "<and"),
                         new TypedValue((int)DxfCode.LayerName,cassLayerName),
                         new TypedValue((int)DxfCode.Start, "TEXT"),//单行文字,多行文字为MTEXT
                         new TypedValue((int)DxfCode.Operator, "and>")
                        };
                    SelectionFilter sf = new SelectionFilter(tvs);
                    PromptSelectionResult psr = ed.SelectAll(sf);
                    if (psr.Status == PromptStatus.OK)
                    {
                        SelectionSet SS = psr.Value;
                        ObjectId[] idArray = SS.GetObjectIds();
                        for (int i = 0; i < idArray.Length; i++)
                        {
                            DBText ent = trans.GetObject(idArray[i], OpenMode.ForWrite) as 
DBText;
                            ent.TextStyleId = styleID;
                        }
                    }
                }
                trans.Commit();
            }
            catch (Exception ex)
            {

            }
            finally
            {
                if (trans != null)
                    trans.Dispose();
                if (docLock != null)
                    docLock.Dispose();
            }
        }