如何使用 iText 7 将 PDF 写入 HttpResponseMessage

Question

我正在尝试生成 PDF 并使用 iText 7 和 iText7.pdfHtml 库将其写入 HTTP 响应。

PDF 的 HTML 内容存储在 StringBuilder 对象中。

不确定这样做的正确过程是什么，因为一旦我使用 HtmlConverter.ConvertToPdf，MemoryStream 就会关闭，我无法访问字节。我收到以下异常：

System.ObjectDisposedException: Cannot access a closed Stream.

HttpResponseMessage httpResponseMessage = new HttpResponseMessage();
StringBuilder htmlText = new StringBuilder();
htmlText.Append("<html><body><h1>Hello World!</h1></body></html>");
using (MemoryStream memoryStream = new MemoryStream())
{
    using (PdfWriter pdfWriter = new PdfWriter(memoryStream))
    {
        PdfDocument pdfDocument = new PdfDocument(pdfWriter);
        Document document = new Document(pdfDocument);

        string headerText = "my header";
        string footerText = "my footer";

        pdfDocument.AddEventHandler(PdfDocumentEvent.END_PAGE, new HeaderFooterEventHandler(document, headerText, footerText));

        HtmlConverter.ConvertToPdf(htmlText.ToString(), pdfWriter);

        memoryStream.Flush();
        memoryStream.Seek(0, SeekOrigin.Begin);

        byte[] bytes = new byte[memoryStream.Length];
        memoryStream.Read(bytes, 0, (int)memoryStream.Length);

        Stream stream = new MemoryStream(bytes);
        httpResponseMessage.Content = new StreamContent(stream);

        httpResponseMessage.Content.Headers.ContentType = MediaTypeHeaderValue.Parse("application/pdf");
        httpResponseMessage.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
        {
            FileName = "sample.pdf"
        };
        httpResponseMessage.StatusCode = HttpStatusCode.OK;
    }//end using pdfwriter
}//end using memory stream

编辑添加了 PdfDocument 和 Document 对象来操作 header/footer 和新页面。

Answer 1

利用你有一个 MemoryStream 并替换

    memoryStream.Flush();
    memoryStream.Seek(0, SeekOrigin.Begin);

    byte[] bytes = new byte[memoryStream.Length];
    memoryStream.Read(bytes, 0, (int)memoryStream.Length);

来自

byte[] bytes = memoryStream.ToArray();

该方法被记录为也适用于封闭的内存流。

如何使用 iText 7 将 PDF 写入 HttpResponseMessage

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