C# Pdf添加页码（iTextSharp）

通过Nuget添加iTextSharp引用，具体代码如下

        /// <summary>
        /// 添加页码
        /// </summary>
        /// <param name="pdfPath">pdf文件</param>
        /// <param name="outPath">输出文件位置</param>
        public static void PdfAddPageNumber(string pdfPath, string outPath)
        {
            //读取pdf
            iTextSharp.text.pdf.PdfReader reader = new iTextSharp.text.pdf.PdfReader(pdfPath);
            //创建新pdf
            System.IO.Stream outStream = new System.IO.FileStream(outPath, System.IO.FileMode.Create, System.IO.FileAccess.Write, System.IO.FileShare.None);
            iTextSharp.text.pdf.PdfStamper stamper = new iTextSharp.text.pdf.PdfStamper(reader, outStream); ;
            int pdfTotalPage = reader.NumberOfPages;//总页数
            //第一页pdf尺寸
            iTextSharp.text.Rectangle psize = reader.GetPageSize(1);
            float width = psize.Width;
            float height = psize.Height;
            iTextSharp.text.pdf.PdfContentByte content;
            //【C:\WINDOWS\Fonts】系统字体存放位置
            iTextSharp.text.pdf.BaseFont font = iTextSharp.text.pdf.BaseFont.CreateFont(@"C:\WINDOWS\Fonts\SIMFANG.TTF", iTextSharp.text.pdf.BaseFont.IDENTITY_H, iTextSharp.text.pdf.BaseFont.EMBEDDED);
            iTextSharp.text.pdf.PdfGState gs = new iTextSharp.text.pdf.PdfGState();
            ///添加页码
            for (int i = 1; i <= pdfTotalPage; i++)
            {
                content = stamper.GetOverContent(i);//添加在内容上层，GetUnderContent内容下层
                gs.FillOpacity = 0.8f;//设置透明度
                content.SetGState(gs);
                content.BeginText();
                content.SetColorFill(iTextSharp.text.BaseColor.BLACK);//设置字体颜色
                content.SetFontAndSize(font, 12);//设置字体大小
                content.ShowTextAligned(iTextSharp.text.Element.ALIGN_CENTER, $"第{i}页，共{pdfTotalPage}页", width / 2 - 5, 35, 0);//设置字体添加位置
                content.EndText();
            }
            stamper.Close();
            reader.Close();
            System.Diagnostics.Process.Start(outPath);
        }

效果如下图所示