準備工作，建立html模板，在需要動態顯示的地方使用佔位符，以便後臺隨時替換。

在Controller裡面，獲取html模板。並替換佔位符。

var result = new SingleRecordResult<string>();
            try
            {
                new GeneratePDFHelper().DeleteOldFile();
                //獲取模板路徑
                var url = Directory.GetCurrentDirectory() + "/Template/DeliveryTemplate.html
 
";
                //讀取html裡面的程式碼
                var HtmlTemplate = new GeneratePDFHelper().getUrltoHtml(url);

                generatePDFView.tripName = _serviceClient.GetTripDetail(generatePDFView.tripId)?.TripName;
                generatePDFView.customerName = _serviceClient.GetCustomerDetail(generatePDFView.customer)?.TradingName;
                generatePDFView.carrierName 
 
= _serviceClient.GetCarrierDetail(generatePDFView.carrier)?.CarrierName;
                generatePDFView.fisheryName = generatePDFView.fishery == 0 ? "" : _serviceClient.GetFisheryDetail(generatePDFView.fishery)?.FisheryName;
                generatePDFView.portName = generatePDFView.port == 0 ? "" : _serviceClient.GetPortDetail(generatePDFView.port)?.PortName;
                //將實體代入方法，替換佔位符
                
 
var HtmlCode = new GeneratePDFHelper().ConvertHtmlofModel(HtmlTemplate, generatePDFView);
                //開始生成PDF
                result.Data =  new GeneratePDFHelper().Generate(HtmlCode, "/OutPut");
            }
            catch (Exception ex)
            {
                result.Status = -1;
                result.Message = ex.Message;
                _logger.LogError(ex, string.Concat(ex.Message));
            }
            return result;

生成PDF的核心程式碼：

    public class GeneratePDFHelper
    {
        public string Generate(string htmlText,string savePath)
        {
            string path = Directory.GetCurrentDirectory() + savePath;
            if (!Directory.Exists(path))
                Directory.CreateDirectory(path);
            //將要生成的PDF名字和路徑
            string filePath = "/Report_" + DateTime.Now.ToString("yyyyMMddHHmmsss") + ".pdf";

            this.ConvertHtmlTextToPDF(htmlText, path + filePath);

            return savePath + filePath;
        }

        public void ConvertHtmlTextToPDF(string htmlText,string filePath)
        {
            if (string.IsNullOrEmpty(htmlText))
            {
                return;
            }
            var fs = new FileStream(filePath, FileMode.Create);
            var doc = new Document(PageSize.A4);
            var pdfWriter = PdfWriter.GetInstance(doc, fs); 
            //重寫PageEventHelper， 輸入PDF頁尾的頁碼

　　　　　　　PageEventHelper pageEventHelper = new PageEventHelper(); 
　　　　　　　pdfWriter.PageEvent = pageEventHelper; 

            doc.Open();

             //插入LOGO 
            if (!string.IsNullOrEmpty(Directory.GetCurrentDirectory() + "/Img/logo.png"))
            {
                Image img = Image.GetInstance(Directory.GetCurrentDirectory() + "/Img/logo.png");
                img.SetAbsolutePosition(20, (doc.PageSize.Height - 130) - 20);
                img.ScaleAbsolute(100, 130);
                doc.Add(img);
            }

            var css = new StreamReader(Directory.GetCurrentDirectory() + "/Template/Report.css").ReadToEnd();
            using (var msCss = new MemoryStream(Encoding.UTF8.GetBytes(css)))
            {
                using (var msHtml = new MemoryStream(Encoding.UTF8.GetBytes(htmlText)))
                {
                    XMLWorkerHelper.GetInstance().ParseXHtml(pdfWriter, doc, msHtml, null, Encoding.UTF8);
                }
            }

            doc.Close();
            fs.Close();
            pdfWriter.Close();


        }
        public string getUrltoHtml(string url)
        {
            string html = "";
            try
            {
                using (StreamReader reader = new StreamReader(url))
                {
                    html = reader.ReadToEnd();
                }
                return html;

            }
            catch
            {
            }
            return "";
        }

        public string ConvertHtmlofModel(string html, GeneratePDFViewModel generatePDF)
        {return html.Replace("{{PrintData}}", DateTime.Now.ToString("dd MMM yyyy HH:mm"))
                       .Replace("{{TripNumber}}", generatePDF.tripName)
                       .Replace("{{Customer}}", generatePDF.customerName)
                       .Replace("{{Address}}", generatePDF.address)
                       .Replace("{{Carrier}}", generatePDF.carrierName)
                       .Replace("{{TrailerNumber}}", generatePDF.trailer)
                       .Replace("{{Consignment}}", generatePDF.consignment)
                       .Replace("{{CarrierContact}}", generatePDF.carrierContact)
                       .Replace("{{CarrierPhone}}", generatePDF.carrierPhone)
                       .Replace("{{TrackingURL}}", generatePDF.trackingurl)
                       .Replace("{{Fishery}}", generatePDF.fisheryName)
                       .Replace("{{Port}}", generatePDF.portName)
                       .Replace("{{PalletCount}}", generatePDF.pallets)
                       .Replace("{{ContainerCount}}", generatePDF.boxes != 0 ? generatePDF.boxes.ToString() : "")
                       .Replace("{{BagCount}}", generatePDF.bags != 0 ? generatePDF.bags.ToString() : "")
                       .Replace("{{ETADate}}", generatePDF.etadate)
                       .Replace("{{ETATime}}", generatePDF.etatime)
                       .Replace("{{Temps}}", temperatureHtml)
                       .Replace("{{Comments}}", generatePDF.Additional)
                       .Replace("{{SpeciesDetail}}", reviewOrder);
        }

        public void DeleteOldFile()
        {
            try
            {
                var temp = Directory.GetCurrentDirectory() + "/OutPut";
                System.IO.DirectoryInfo directoryInfo = new System.IO.DirectoryInfo(temp);
                System.IO.FileInfo[] files = directoryInfo.GetFiles("*.*");
                for (int i = 0; i < files.Length; i++)
                {
                    if (files[i].CreationTime.AddDays(1) < DateTime.Now)
                    {
                        System.IO.File.Delete(files[i].FullName.Trim());
                    }
                }
            }
            catch { 
            }
        }
    }

自定義頁碼的輔助類：

    public class PageEventHelper: PdfPageEventHelper
    {
        PdfContentByte cb;
        PdfTemplate template;
        BaseFont font = BaseFont.CreateFont(@"C:\WINDOWS\Fonts\Arial.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);

        public override void OnOpenDocument(PdfWriter writer, Document document)
        {
            cb = writer.DirectContent;
            template = cb.CreateTemplate(50, 50);
        }

        public override void OnEndPage(PdfWriter writer, Document document)
        {
            base.OnEndPage(writer, document);

            int pageN = writer.PageNumber;
            String text = "Page " + pageN.ToString() + " of ";

            iTextSharp.text.Rectangle pageSize = document.PageSize;

            cb.BeginText();
            cb.SetFontAndSize(font, 12);
            cb.SetTextMatrix(document.LeftMargin, pageSize.GetBottom(document.BottomMargin));
            cb.ShowText(text);

            cb.EndText();

            cb.AddTemplate(template, document.LeftMargin + 60, pageSize.GetBottom(document.BottomMargin));
        }

        public override void OnCloseDocument(PdfWriter writer, Document document)
        {
            base.OnCloseDocument(writer, document);

            template.BeginText();
            template.SetFontAndSize(font, 12);
            template.SetTextMatrix(0, 0);
            template.ShowText("" + (writer.PageNumber));
            template.EndText();

        }
    }