How to Filter Web Content When Export Gridview Data to Excel File

Question

I need to export Gridview data to excel file and achieved the export function using attached code,everything is ok but the content of the excel file to which gridview data exported Contained all Web components, sush as button,textbox,etc. I want to know how to filter those web components. The Code is following,Please help me,thanks.

If DataEmpty = False Then  
       Dim dt As DateTime = Now()             
       Dim Filename As String = dt.ToString("yyMMddhhmmss")             
       Filename = "UserReport_" + Filename + ".xls"              
       GridView_UserList.AllowPaging = False            
       GridView_UserList.Columns(0).Visible = False            
       GridView_UserList.DataSource = BindData()             
       GridView_UserList.DataBind()               
       GridView_UserList.HeaderRow.BackColor = Drawing.Color.White             
       GridView_UserList.HeaderRow.ForeColor = Drawing.Color.Black               
       HttpContext.Current.Response.Charset = "GB2312"            
       HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8      
       HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(Filename, System.Text.Encoding.UTF8).ToString())             
       HttpContext.Current.Response.ContentType = "application/vnd.ms-excel"            GridView_UserList.Page.EnableViewState = False            
       Dim oStringWriter As StringWriter = New StringWriter             
       Dim oHtmlTextWriter As HtmlTextWriter = New HtmlTextWriter(oStringWriter)     
       Try                    
          GridView_UserList.RenderControl(oHtmlTextWriter)                 
          Response.Output.Write(oStringWriter.ToString)                 
          Response.Flush()                 
          Response.End()               
      Catch ex As Exception                   
          WriteOperatorMsg("Export Excel file", Filename, "Failed", ex.Message.ToString)               
     End Try            
End If