最近在做关于PDF文档添加水印的功能，折腾了好久，终于好了。以下做个记录：

首先会用到iTextSharp组件，大家可以去官网下载，同时我也会在本文中附加进来。

代码中添加引用为：

 

usingSystem;
usingSystem.Collections.Generic;
usingSystem.Linq; usingSystem.Text; usingiTextSharp.text.pdf; usingSystem.IO; usingiTextSharp.text;

创建一个显示指定图片的pdf

/// <summary>/// 创建一个显示指定图片的pdf/// </summary>/// <param name="picPdfPath"></param>/// <param name="picPath"></param>/// <returns></returns>public static bool CreatePDFByPic(string picPdfPath,string picPath){//新建一个文档Document doc = new Document();try{//建立一个书写器(Writer)与document对象关联PdfWriter.GetInstance(doc, new FileStream(picPdfPath, FileMode.Create, FileAccess.ReadWrite));//打开一个文档doc.Open();//向文档中添加内容Image img = Image.GetInstance(picPath);//img.SetAbsolutePosition();doc.Add(img);return true;}catch (Exception ex){return false;throw ex;}finally{if (doc != null){doc.Close();}}}

为PDF文档添加图片水印

/// <summary>/// 加图片水印/// </summary>/// <param name="inputfilepath"></param>/// <param name="outputfilepath"></param>/// <param name="ModelPicName"></param>/// <param name="top"></param>/// <param name="left"></param>/// <returns></returns>public static bool PDFWatermark(string inputfilepath, string outputfilepath, string ModelPicName, float top, float left){//throw new NotImplementedException();PdfReader pdfReader = null;PdfStamper pdfStamper = null;try{pdfReader = new PdfReader(inputfilepath);int numberOfPages = pdfReader.NumberOfPages;iTextSharp.text.Rectangle psize = pdfReader.GetPageSize(1);float width = psize.Width;float height = psize.Height;pdfStamper = new PdfStamper(pdfReader, new FileStream(outputfilepath, FileMode.Create));PdfContentByte waterMarkContent;iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(ModelPicName);image.GrayFill = 20;//透明度，灰色填充//image.Rotation//旋转//image.RotationDegrees//旋转角度//水印的位置 if (left < 0){left = width/2 - image.Width + left;}//image.SetAbsolutePosition(left, (height - image.Height) - top);image.SetAbsolutePosition(left, (height/2 - image.Height) - top);//每一页加水印,也可以设置某一页加水印 for (int i = 1; i <= numberOfPages; i++){//waterMarkContent = pdfStamper.GetUnderContent(i);//内容下层加水印waterMarkContent = pdfStamper.GetOverContent(i);//内容上层加水印waterMarkContent.AddImage(image);}//strMsg = "success";return true;}catch (Exception ex){throw ex;}finally{if (pdfStamper != null)pdfStamper.Close();if (pdfReader != null)pdfReader.Close();}}

添加普通偏转角度文字水印

/// <summary>/// 添加普通偏转角度文字水印/// </summary>/// <param name="inputfilepath"></param>/// <param name="outputfilepath"></param>/// <param name="waterMarkName"></param>/// <param name="permission"></param>public static void setWatermark(string inputfilepath, string outputfilepath,string waterMarkName){PdfReader pdfReader = null;PdfStamper pdfStamper = null;            //获取所用权PdfReader.unethicalreading = true;try{pdfReader = new PdfReader(inputfilepath);pdfStamper = new PdfStamper(pdfReader, new FileStream(outputfilepath, FileMode.Create));int total = pdfReader.NumberOfPages + 1;iTextSharp.text.Rectangle psize = pdfReader.GetPageSize(1);float width = psize.Width;float height = psize.Height;PdfContentByte content;BaseFont font = BaseFont.CreateFont(@"C:\WINDOWS\Fonts\SIMFANG.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);PdfGState gs = new PdfGState();for (int i = 1; i < total; i++) {content = pdfStamper.GetOverContent(i);//在内容上方加水印//content = pdfStamper.GetUnderContent(i);//在内容下方加水印//透明度gs.FillOpacity = 0.3f;content.SetGState(gs);//content.SetGrayFill(0.3f);//开始写入文本content.BeginText();content.SetColorFill(BaseColor.LIGHT_GRAY);content.SetFontAndSize(font, 100);content.SetTextMatrix(0, 0);content.ShowTextAligned(Element.ALIGN_CENTER, waterMarkName, width / 2 - 50,height / 2 - 50, 55);//content.SetColorFill(BaseColor.BLACK);//content.SetFontAndSize(font, 8);//content.ShowTextAligned(Element.ALIGN_CENTER, waterMarkName, 0, 0, 0);content.EndText();}}catch (Exception ex){throw ex;}finally{if (pdfStamper != null)pdfStamper.Close();if (pdfReader != null)pdfReader.Close();}}

添加倾斜水印

/// <summary>/// 添加倾斜水印/// </summary>/// <param name="inputfilepath"></param>/// <param name="outputfilepath"></param>/// <param name="waterMarkName"></param>/// <param name="userPassWord"></param>/// <param name="ownerPassWord"></param>/// <param name="permission"></param>public static void setWatermark(string inputfilepath, string outputfilepath, string waterMarkName, string userPassWord, string ownerPassWord, int permission){PdfReader pdfReader = null;PdfStamper pdfStamper = null;try{pdfReader = new PdfReader(inputfilepath);pdfStamper = new PdfStamper(pdfReader, new FileStream(outputfilepath, FileMode.Create));// 设置密码   //pdfStamper.SetEncryption(false,userPassWord, ownerPassWord, permission); int total = pdfReader.NumberOfPages + 1;PdfContentByte content;BaseFont font = BaseFont.CreateFont(@"C:\WINDOWS\Fonts\SIMFANG.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);PdfGState gs = new PdfGState();gs.FillOpacity = 0.2f;//透明度int j = waterMarkName.Length;char c;int rise = 0;for (int i = 1; i < total; i++){rise = 500;content = pdfStamper.GetOverContent(i);//在内容上方加水印//content = pdfStamper.GetUnderContent(i);//在内容下方加水印content.BeginText();content.SetColorFill(BaseColor.DARK_GRAY);content.SetFontAndSize(font, 50);// 设置水印文字字体倾斜 开始 if (j >= 15){content.SetTextMatrix(200, 120);for (int k = 0; k < j; k++){content.SetTextRise(rise);c = waterMarkName[k];content.ShowText(c + "");rise -= 20;}}else{content.SetTextMatrix(180, 100);for (int k = 0; k < j; k++){content.SetTextRise(rise);c = waterMarkName[k];content.ShowText(c + "");rise -= 18;}}// 字体设置结束 content.EndText();// 画一个圆 //content.Ellipse(250, 450, 350, 550);//content.SetLineWidth(1f);//content.Stroke(); } }catch (Exception ex){throw ex;}finally{if (pdfStamper != null)pdfStamper.Close();if (pdfReader != null)pdfReader.Close();}}

调用方法的例子：

string path = "D://my.pdf";HtmlToPDFUtil.HtmlToPdf(Request.Url.AbsoluteUri, path);//HtmlToPDFUtil.HtmlToPdf(sbUrlList.ToString(), path);PDFSetWaterMark.PDFWatermark(path, "D://my.pdf", Server.MapPath("/HtmlToPdf/Tools/sy.bmp"), 0, 0);PDFSetWaterMark.setWatermark("D://my.pdf", "D://my2.pdf", "TEST");//PDFSetWaterMark.setWatermark("D://my.pdf", "D://my2.pdf", "TEST", "", "", 1);