使用c＃替换服务器文件夹asp.net中的pdf文件的选项？

Question

如何使用带有c＃的asp.net替换服务器文件夹中的pdf文件？ 当我们生成Pdf时，时间不是问题，但pdf更新是一个无法解决的问题，我们在发送邮件附件时遇到了这个问题。 你可以帮我吗。我试过这个吗？

string fileloc = Server.MapPath("~/InvoiceFolder/" + lblprintinvoiceno_nmail.Text + ".pdf");
string newFile = Server.MapPath("~/InvoiceFolder/" + lblprintinvoiceno_nmail.Text + ".pdf");
if (System.IO.File.Exists(fileloc))
{
    System.IO.File.Delete(newFile);
}

iTextSharp.text.Table table = new iTextSharp.text.Table(GridView222.Columns.Count);
table.Cellpadding = 5;

//Set the column widths of the table
int[] widths = new int[GridView222.Columns.Count];
for (int x = 0; x < GridView222.Columns.Count; x++)
{
    widths[x] = (int)GridView222.Columns[x].ItemStyle.Width.Value;
    string cellText = Server.HtmlDecode(GridView222.HeaderRow.Cells[x].Text);
    iTextSharp.text.Cell cell = new iTextSharp.text.Cell(cellText);
    cell.BackgroundColor = new Color(System.Drawing.ColorTranslator.FromHtml("#DEDEE1"));
    table.AddCell(cell);
}
table.SetWidths(widths);

//getting rows from GridView to table
string GridText = "";
for (int i = 0; i < GridView222.Rows.Count; i++)
{
    if (GridView222.Rows[i].RowType == DataControlRowType.DataRow)
    {
        for (int j = 0; j < GridView222.Columns.Count; j++)
        {
            if (j == 0)
            {
                int slno = i + 1;
                GridText = slno.ToString();
            }
            else
            {
                GridText = Server.HtmlDecode(GridView222.Rows[i].Cells[j].Text);
            }
            iTextSharp.text.Cell cell = new iTextSharp.text.Cell(GridText);
            table.AddCell(cell);
        }
    }
}

//Start Create PDF
Document Doc = new Document(PageSize.A2, 7f, 7f, 7f, 0f);
StringWriter sw = new StringWriter();
HtmlTextWriter hw = new HtmlTextWriter(sw);
pnlconvert1.RenderControl(hw);
StringReader sr = new StringReader(sw.ToString());
PdfWriter.GetInstance(Doc, new FileStream(fileloc, FileMode.Create));
HTMLWorker htmlparser = new HTMLWorker(Doc);
Doc.Open();
htmlparser.Parse(sr);
Doc.Add(table);
StringWriter sw1 = new StringWriter();
HtmlTextWriter hw1 = new HtmlTextWriter(sw1);
pnlconvert3.RenderControl(hw1);
StringReader sr1 = new StringReader(sw1.ToString());
htmlparser.Parse(sr1);
Doc.Close();
//End Create PDF

//Send Mail
System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient();
smtp.Host = "smtp.live.com";
smtp.EnableSsl = true;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Credentials = new System.Net.NetworkCredential("user", "ped");
System.Net.Mail.MailMessage oMsg = new System.Net.Mail.MailMessage();
//MailAddress @add = new MailAddress("poobal@foresightgroup.in");
MailAddress @add = new MailAddress(txtinvoicemail.Text);
oMsg.CC.Add(new MailAddress("mail"));
oMsg.From = new MailAddress("mail");
oMsg.To.Add(@add);
oMsg.Subject = "Quotation";
oMsg.Attachments.Add(new Attachment(fileloc));
oMsg.Body = "Sir ," + "<br/>" + "kindly see the attached Invoice for your ready reference.";
oMsg.IsBodyHtml = true;
smtp.Send(oMsg);
oMsg.Attachments.Clear();

txtinvoicemail.Text = "";