native excel 文件已经打开的判断

   book := TXLSWorkbook.Create;
   try
      if  book.Open(AFIleName) = - then
      begin
         raise Exception.Create('请检查导入的文件是否存在或Excel已经处于打开状态(如果已经打开，请尝试关闭文件再导入)');
      end;

      ws := book.WorkSheets[];
      if ws.UsedRange.Rows.Count =   then
      begin
          Exit;
      end;