在asp.net中导出为pdf时出现的空白pdf

Question

我有一个网页表单。我已经在一个div中添加了所有内容，并希望以pdf格式导出此div。以pdf格式导出时pdf即将出现。

 protected void btnExport_Click(object sender, EventArgs e)
    {
        String DownloadFile = String.Format("{0}Targetkeywordsofdt-{1}", ddlproject.SelectedItem.Text, txtEndDate.Text.ToString() + ".pdf");
        Response.AddHeader("content-disposition", "attachment;filename=" + DownloadFile);
        Response.ContentType = "application/pdf";
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        StringWriter sw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(sw);
        PdfReport.RenderControl(hw);

        StringReader sr = new StringReader(sw.ToString());
        Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 100f, 0f);

        HTMLWorker htmlparser = new HTMLWorker(pdfDoc);

        PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
        string strpath = Server.MapPath("~") + "/Temp/" + ddlproject.SelectedItem.Text.Trim() + ".pdf";
        PdfWriter writer = PdfWriter.GetInstance(pdfDoc, new FileStream(strpath, FileMode.Create));

        pdfDoc.Open();
        htmlparser.Parse(sr);
        pdfDoc.Close();
        pdfDoc.Dispose();
        Response.Write(pdfDoc);
        Response.End();
    }