Response.Clear();
     Response.Buffer = true;
     Response.Charset = "GB2312";
     Response.AppendHeader("Content-Disposition", "attachment;filename=FileName.xls");
     // 如果设置为 GetEncoding("GB2312");导出的文件将会出现乱码！！！
     Response.ContentEncoding = System.Text.Encoding.UTF7;
     Response.ContentType = "application/ms-excel";//设置输出文件类型为excel文件。 
     System.IO.StringWriter oStringWriter = new System.IO.StringWriter();
     System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
     this.GridView1.RenderControl(oHtmlTextWriter);
     Response.Output.Write(oStringWriter.ToString());
     Response.Flush();
     Response.End();