mvc 将展示内容以Pdf格式下载下来

之前有写过根据文件地址下载的例子，今天碰上没有文件地址，直接把文件内容存到数据库中的情况，同时需要提供下载功能，并且是pdf的；首先需要引用itextsharp.dll，里面有封装好的pdf类和字体类；直接上代码：

  private static readonly string 标楷体Path = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Fonts),
   "KAIU.TTF");//标楷体

 public ActionResult met_word_automation(string al_id)
        {
            ClassicCaseService.zkdz_classic_case _zkdz_classic_case = ws.IGetModel(al_id);
           string htmlText = "<div style='text-align:center;'><h2>" + _zkdz_classic_case.Title + "</h2></div>";
            htmlText += "<div style='float:right'>" + _zkdz_classic_case.CaseNo + "</div>";
            htmlText += _zkdz_classic_case.Content;

            if (string.IsNullOrEmpty(htmlText))
            {
                return null;
            }
            //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
            htmlText = "<p>" + htmlText + "</p>";

            MemoryStream outputStream = new MemoryStream();//要把PDF写到哪个串流
            byte[] data = Encoding.UTF8.GetBytes(htmlText);//字串转成byte[]
            MemoryStream msInput = new MemoryStream(data);
            Document doc = new Document();//要写PDF的文件，建构子没填的话预设直式A4
            PdfWriter writer = PdfWriter.GetInstance(doc, outputStream);
            //指定文件预设开档时的缩放为100%
            PdfDestination pdfDest = new PdfDestination(PdfDestination.XYZ, 0, doc.PageSize.Height, 1f);
            //水印字体
            BaseFont bf = BaseFont.CreateFont(标楷体Path, BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
            //生成水印
            writer.PageEvent = new PdfEventHanler("真快电子送达科技服务有限公司", bf);//_zkdz_classic_case.TrialCourt  谭亮修改为公司名
            //开启Document文件 
            doc.Open();
            //使用XMLWorkerHelper把Html parse到PDF档里
            XMLWorkerHelper.GetInstance().ParseXHtml(writer, doc, msInput, null, Encoding.UTF8, new UnicodeFontFactory());
            //将pdfDest设定的资料写到PDF档
            PdfAction action = PdfAction.GotoLocalPage(1, pdfDest, writer);
            writer.SetOpenAction(action);
            doc.Close();
            msInput.Close();
            outputStream.Close();
            return File(outputStream.ToArray(), "application/pdf", _zkdz_classic_case.CaseNo + ".pdf");

        }