因个人需求，需要将html格式转换成PDF并加上水印图片。于是乎第一次接触这种需求的小菜鸟博主我，在某度搜索引擎上不断地查阅关键字资料、踩坑，终于有了一个相应的解决方案。以下是解决步骤，记录下来方便以后的回顾，以及各位大神们的品鉴。
1、在 NuGet 搜索 itextsharp 关键字 下载以下截图圈中的两个包，一般下载完后项目会自动引用。
2、在项目文件中引入以下命名空间（建议下面提及的代码封装成类库，方便项目间调用，个人取舍）
3、Html字符串转pdf文件流，加水印图片以及未加水印重载 精简帮助类（由博主踩坑整理，仅完成个人业务需求）
1 /// <summary> 2 /// Html字符串转PDF输出帮助类 3 /// </summary> 4 public class HtmlToPdfHelper 5 { 6 #region HtmlToPDF 7 8 /// <summary> 9 /// 判断是否有乱码10 /// </summary>11 /// <param name="txt"></param>12 /// <returns></returns>13 private static bool IsMessyCode(string txt)14 {15 var bytes = Encoding.UTF8.GetBytes(txt);16 for (var i = 0; i < bytes.Length; i++)17 {18 if (i < bytes.Length - 3)19 if (bytes[i] == 239 && bytes[i + 1] == 191 && bytes[i + 2] == 189)20 {21 return true;22 }23 }24 return false;25 }26 27 /// <summary>28 /// 将Html字符串 输出到PDF档里29 /// </summary>30 /// <param name="htmlText"></param>31 /// <returns></returns>32 public static byte[] ConvertHtmlTextToPdf(string htmlText)33 {34 return ConvertHtmlTextToPdf(htmlText, "", 0, 0, 0, 0);35 }36 37 /// <summary>38 /// 将Html字符串 输出到PDF档里,并添加水印39 /// </summary>40 /// <param name="htmlText">网页代码</param>41 /// <param name="picPath">水印路径</param>42 /// <param name="left">距离左边距离</param>43 /// <param name="top">距顶部距离</param>44 /// <param name="width">水印宽度</param>45 /// <param name="height">水印高度</param>46 /// <returns></returns>47 public static byte[] ConvertHtmlTextToPdf(string htmlText, string picPath, int left, int top, int width, int height)48 {49 if (string.IsNullOrEmpty(htmlText))50 {51 return null;52 }53 //避免当htmlText无任何html tag标签的纯文字时，转PDF时会挂掉，所以一律加上<p>标签54 htmlText = "<p>" + htmlText + "</p>";55 MemoryStream outputStream = new MemoryStream();//要把PDF写到哪个串流56 byte[] data = Encoding.UTF8.GetBytes(htmlText);//字串转成byte[]57 MemoryStream msInput = new MemoryStream(data);58 Document doc = new Document();//要写PDF的文件，建构子没填的话预设直式A459 PdfWriter writer = PdfWriter.GetInstance(doc, outputStream);60 //指定文件预设开档时的缩放为100%61 PdfDestination pdfDest = new PdfDestination(PdfDestination.XYZ, 0, doc.PageSize.Height, 1f);62 //开启Document文件 63 doc.Open();64 65 //写入水印图片66 if (!string.IsNullOrEmpty(picPath))67 {68 Image img = Image.GetInstance(picPath);69 //设置图片的位置70 img.SetAbsolutePosition(width + left, (doc.PageSize.Height - height) - top);71 //设置图片的大小72 img.ScaleAbsolute(width, height);73 doc.Add(img);74 }75 try76 {77 //使用XMLWorkerHelper把Html parse到PDF档里79 XMLWorkerHelper.GetInstance().ParseXHtml(writer, doc, msInput, null, Encoding.UTF8);80 //将pdfDest设定的资料写到PDF档81 PdfAction action = PdfAction.GotoLocalPage(1, pdfDest, writer);82 writer.SetOpenAction(action);83 }84 catch (Exception)85 {86 return null;87 }88 doc.Close();89 msInput.Close();90 outputStream.Close();91 //回传PDF档案 92 return outputStream.ToArray();94 }95 96 #endregion97 98 }
4、获取网页字符串的方法
1 /// <summary> 2 /// 获取网站内容，包含了 HTML+CSS+JS 3 /// </summary> 4 /// <returns>String返回网页信息</returns> 5 public static string GetWebContent(string inpath) 6 { 7 try 8 { 9 WebClient myWebClient = new WebClient();10 //获取或设置用于向Internet资源的请求进行身份验证的网络凭据11 myWebClient.Credentials = CredentialCache.DefaultCredentials;12 //从指定网站下载数据13 Byte[] pageData = myWebClient.DownloadData(inpath);14 //如果获取网站页面采用的是GB2312，则使用这句15 string pageHtml = Encoding.UTF8.GetString(pageData);16 bool isBool = IsMessyCode(pageHtml);//判断使用哪种编码 读取网页信息17 if (!isBool)18 {19 string pageHtml1 = Encoding.UTF8.GetString(pageData);20 pageHtml = pageHtml1;21 }22 else23 {24 string pageHtml2 = Encoding.Default.GetString(pageData);25 pageHtml = pageHtml2;26 }27 return pageHtml;28 }29 catch (WebException webEx)30 {31 return webEx.Message;32 }33 }
5、MVC设计模式下获取控制器视图Html方法，很XX的一个问题就是只能获取调用此方法的控制器下所有视图，不能跨控制器获取视图，有待优化
1 /// <summary> 2 /// 获取MVC视图Html 3 /// </summary> 4 /// <param name="context">控制器上下文</param> 5 /// <param name="viewName">视图名称</param> 6 /// <param name="param"></param> 7 /// <returns></returns> 8 public static string GetViewHtml(ControllerContext context, string viewName) 9 {10 if (string.IsNullOrEmpty(viewName))11 viewName = context.RouteData.GetRequiredString("action");12 using (var sw = new StringWriter())13 {14 ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(context, viewName);15 var viewContext = new ViewContext(context, viewResult.View, context.Controller.ViewData, context.Controller.TempData, sw);16 try17 {18 viewResult.View.Render(viewContext, sw);19 }20 catch (Exception ex)21 {22 throw;23 }24 25 return sw.GetStringBuilder().ToString();26 }27 }
6、将pdf流输出至客户浏览器下载方法
1 /// <summary> 2 /// 将pdf文件流输出至浏览器下载 3 /// </summary> 4 /// <param name="pdfFile">PDF文件流</param> 5 public static void PdfDownload(byte[] pdfFile) 6 { 7 byte[] buffer = pdfFile; 8 Stream iStream = new MemoryStream(buffer); 9 try10 {11 int length;12 long dataToRead;13 string filename = DateTime.Now.ToString("yyyyMMddHHmmss") + ".pdf";//保存的文件名称14 dataToRead = iStream.Length;15 HttpContext.Current.Response.Clear();16 HttpContext.Current.Response.ClearHeaders();17 HttpContext.Current.Response.ClearContent();18 HttpContext.Current.Response.ContentType = "application/pdf"; //文件类型 19 HttpContext.Current.Response.AddHeader("Content-Length", dataToRead.ToString());//添加文件长度，进而显示进度 20 HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, Encoding.UTF8));21 while (dataToRead > 0)22 {23 if (HttpContext.Current.Response.IsClientConnected)24 {25 length = buffer.Length;26 HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);27 HttpContext.Current.Response.Flush();28 buffer = new Byte[length];29 dataToRead = dataToRead - length;30 }31 else32 {33 dataToRead = -1;34 }35 }36 }37 catch (Exception ex)38 {39 HttpContext.Current.Response.Write("文件下载时出现错误!");40 }41 finally42 {43 if (iStream != null)44 {45 iStream.Close();46 }47 //结束响应，否则将导致网页内容被输出到文件，进而文件无法打开 48 HttpContext.Current.Response.Flush();49 HttpContext.Current.Response.End();50 51 }52 }
7、MVC控制器下调用Demo（步骤4、6 方法封装至帮助类）
1 public class HomeController : Controller 2 { 3 // 4 // GET: /Home/ 5 6 public ActionResult Index() 7 { 8 //从网址下载Html字符串(方法一) 9 string inpath = System.Web.HttpContext.Current.Server.MapPath("~/PDFTemplate/test.html");10 string htmlText = HtmlToPdfHelper.GetWebContent(inpath);//此处调用步骤4方法11 12 //获取MVC视图Html字符串(方法二)13 //string htmlText = GetViewHtml(ControllerContext, "Test");//此处调用步骤5方法14 15 //水印图片路径16 string picPath = Server.MapPath("~/PDFTemplate/TemplateImg/authentication-iocn.png");17 //html转pdf并加上水印18 byte[] pdfFile = HtmlToPdfHelper.ConvertHtmlTextToPdf(htmlText, picPath, 100, 200, 100, 100);19 //输出至客户端20 HtmlToPdfHelper.PdfDownload(pdfFile);//此处调用步骤6方法21 22 return View();23 }24 25 public ActionResult Test()26 {27 return View();28 }29 30 /// <summary>31 /// 获取MVC视图Html32 /// </summary>33 /// <param name="context"></param>34 /// <param name="viewName">视图名称</param>35 /// <returns></returns>36 public static string GetViewHtml(ControllerContext context, string viewName)37 {38 if (string.IsNullOrEmpty(viewName))39 viewName = context.RouteData.GetRequiredString("action");40 using (var sw = new StringWriter())41 {42 ViewEngineResult viewResult = ViewEngines.Engines.FindPartialView(context, viewName);43 var viewContext = new ViewContext(context, viewResult.View, context.Controller.ViewData,44 context.Controller.TempData, sw);45 try46 {47 viewResult.View.Render(viewContext, sw);48 }49 catch (Exception ex)50 {51 throw;52 }53 54 return sw.GetStringBuilder().ToString();55 }56 }57 }
总结：我理解的解决思路是将html读取转换成字符串，之后再通过 itextsharp 转换成 pdf 比特币 传输至客户端或直接保存至服务器生成链接供用户下载。（新手上路，不妥之处，欢迎各位大神指教）
以上代码仅满足个人业务逻辑需求，谢谢浏览。
