将网格视图写入Excel页

我得到以下错误

Error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.

我想把表格放在Excel中单击

Sub bttntxtfile_Click(ByVal sender As Object, ByVal e As EventArgs)
    GridViewExportUtil.Export("Customers.xls", GridView1)
End Sub

public class GridViewExportUtil
{

public static void Export(string fileName, GridView gv)
{
    HttpContext.Current.Response.Clear();
    HttpContext.Current.Response.AddHeader(
        "content-disposition", string.Format("attachment; filename={0}", fileName));
    HttpContext.Current.Response.ContentType = "application/ms-excel";

    using (StringWriter sw = new StringWriter())
    {
        using (HtmlTextWriter htw = new HtmlTextWriter(sw))
        {
            //  Create a form to contain the grid
            Table table = new Table();

            //  add the header row to the table
            if (gv.HeaderRow != null)
            {
                GridViewExportUtil.PrepareControlForExport(gv.HeaderRow);
                table.Rows.Add(gv.HeaderRow);
            }

            //  add each of the data rows to the table
            foreach (GridViewRow row in gv.Rows)
            {
                GridViewExportUtil.PrepareControlForExport(row);
                table.Rows.Add(row);
            }

            //  add the footer row to the table
            if (gv.FooterRow != null)
            {
                GridViewExportUtil.PrepareControlForExport(gv.FooterRow);
                table.Rows.Add(gv.FooterRow);
            }

            //  render the table into the htmlwriter
            table.RenderControl(htw);

            //  render the htmlwriter into the response
           HttpContext.Current.Response.Write(sw.ToString());

        }
    }
}

/// <summary>
/// Replace any of the contained controls with literals
/// </summary>
/// <param name="control"></param>
private static void PrepareControlForExport(Control control)
{
    for (int i = 0; i < control.Controls.Count; i++)
    {
        Control current = control.Controls[i];
        if (current is LinkButton)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as LinkButton).Text));
        }
        else if (current is ImageButton)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as ImageButton).AlternateText));
        }
        else if (current is HyperLink)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as HyperLink).Text));
        }
        else if (current is DropDownList)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as DropDownList).SelectedItem.Text));
        }
        else if (current is CheckBox)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as CheckBox).Checked ? "True" : "False"));
        }

        if (current.HasControls())
        {
            GridViewExportUtil.PrepareControlForExport(current);
        }
    }
}
}

我有两个response.redirects,但是我把它们注释掉了,仍然得到了错误。以前有人见过这个错误吗?我做错什么了吗?

我认为这与httpcontext.current.response.clear和httpcontext.current.response.addheader行有关