下载DataGrid内容，作为Excel可打开的文件

using  System;
using  System.Web;
using  System.Web.UI;
using  System.Web.UI.WebControls;

namespace  AIS.Web
{
     ///   <summary>
     ///  把GridView作为文件下载，可供Excel打开
     ///   </summary>
     public   class  DataGridToFile
    {
         public  DataGridToFile()
        {}

         public   static   void  Download(DataGrid dg)
        {
            Download(dg,  " report_ "   +  DateTime.Now.ToString( " yyyyMMdd " )  + " .xls "  );
        }

         public   static   void  Download(DataGrid dg,  string  fileName)
        {
            TranComplexCtlToLiteral(dg);

            System.IO.StringWriter sw  =   new  System.IO.StringWriter();
            HtmlTextWriter htw = new  HtmlTextWriter(sw);
            dg.RenderControl(htw);

            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.Buffer = false ;
            HttpContext.Current.Response.AddHeader( " Content-Disposition " ,  " attachment; filename= " + fileName); 
            HttpContext.Current.Response.ContentType  =   " application/excel " ; 
            HttpContext.Current.Response.Charset = " GB2312 " ;
            HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding( " GB2312 " ); 
            HttpContext.Current.Response.Write(sw.ToString()); 
            HttpContext.Current.Response.End(); 
        }


         ///   <summary>
         ///  把复杂控件都变为只显示文字的控件
         ///   </summary>
         private   static   void  TranComplexCtlToLiteral(WebControl ctl)
        {
             if (ctl == null )  return ;
             if (ctl.HasControls() == false )  return ;

             for ( int  i  = 0 ; i  <  ctl.Controls.Count; i ++ )
            {
                Literal l = new  Literal();
                WebControl curChild = ctl.Controls[i]  as  WebControl;

                 if (curChild  is  HyperLink)
                {
                    HyperLink hl = curChild  as  HyperLink;
                    l.Text  =  hl.Text;
                    ctl.Controls.Remove(curChild);
                    ctl.Controls.AddAt(i,l);
                }
                 else   if (curChild  is  DropDownList)
                {
                    DropDownList ddl = curChild  as  DropDownList;
                    l.Text = ddl.SelectedItem.Text;
                    ctl.Controls.Remove(curChild);
                    ctl.Controls.AddAt(i,l);
                }
                TranComplexCtlToLiteral(curChild);
            }
        }
    }
}