C# 将 PDF 文件附加到 MemoryStream - 无法访问已关闭的流答案

【问题标题】：C# Append PDF file to MemoryStream - Cannot access a closed StreamC# 将 PDF 文件附加到 MemoryStream - 无法访问已关闭的流
【发布时间】：2018-10-14 16:12:45
【问题描述】：

是否可以使用 iTextSharp 将现有 PDF 文件附加到动态创建的 PDF 中？我已经尝试按照下面的代码使用 PdfCopy，但我收到了 Cannot access a closed Stream 错误。

我见过将实际 PDF 文件合并在一起的示例，但我没有存储完成的 PDF，只是将 MemoryStream 输出到 FilestreamResult：

private readonly float _spacingBefore = 3f;

private readonly float _spacingAfter = 3f;

private readonly float _totalWidth = PageSize.A4.Width - 80;

public MemoryStream CreateMemoryStream()
{
    var document = new Document(PageSize.A4, 25, 25, 30, 30);

    var workStream = new MemoryStream();

    PdfWriter.GetInstance(document, workStream);

    var pdfCopy = new PdfCopy(document, workStream);

    document.Open();

    var pdfPTable = new PdfPTable(1)
    {
        TotalWidth = _totalWidth,
        LockedWidth = true,
        SpacingBefore = _spacingBefore,
        SpacingAfter = _spacingAfter
    };

    float[] widths = { 272f };

    pdfPTable.SetWidths(widths);

    var image = Image.GetInstance(HttpContext.Current.Server.MapPath("\\Images\\Logo.png"));
    image.ScaleToFit(125f, 125f);
    image.Alignment = Image.RIGHT_ALIGN;

    var pdfPCell = new PdfPCell(image)
    {
        Border = 0,
        HorizontalAlignment = Element.ALIGN_RIGHT
    };

    pdfPTable.AddCell(pdfPCell);

    document.Add(pdfPTable);

    pdfCopy.AddDocument(new PdfReader(HttpContext.Current.Server.MapPath("/Documents/Test.pdf")));

    if (document != null)
    {
        document.Close();
    }

    var file = workStream.ToArray();

    var memoryStream = new MemoryStream();
    memoryStream.Write(file, 0, file.Length);
    memoryStream.Position = 0;

    return memoryStream;
}

public FileStreamResult Pdf(int id)
{
    var memoryStream = CreateMemoryStream();

    HttpContext.Response.AddHeader("content-disposition", "inline; filename=" + id + ".pdf");

    return File(memoryStream, "application/pdf");
}

我也尝试了以下而不是pdfCopy.AddDocument(new PdfReader(HttpContext.Current.Server.MapPath("/Documents/Test.pdf")));

var pdfReader = new PdfReader(HttpContext.Current.Server.MapPath("/Documents/Test.pdf"));

var numberOfPages = pdfReader.NumberOfPages;

for (var i = 0; i < numberOfPages;)
{
    pdfCopy.AddPage(pdfCopy.GetImportedPage(pdfReader, ++i));
}

无论采用哪种方法，我仍然会收到 Cannot access a closed Stream 错误。

任何帮助将不胜感激:-)

【问题讨论】：

我的 git github.com/fals/codingfirst/blob/master/random/… 中有这段代码用于合并文件。我还注意到您对 PdfWriter.GetInstance(document, workStream); 使用相同的流实例；
我正在尝试在内存中创建一个 PDF，一旦创建了初始文档，我希望将一个实际的 PDF 附加到动态创建的 PDF 的末尾，然后将连接的结果呈现给浏览器。
是的，我注意到，我 github 上的代码所做的与您的相同，在内存中，所有内容，我创建多个文档，然后附加然后插入循环，您也可以这样做。跨度>
谢谢，我查看了你的代码，好消息是错误已经消失，我得到了一个 PDF，但它只是附加的 PDF，而不是动态的 PDF，然后是附加的。我也尝试过使用document.Add(pdfPTable); document.NewPage(); pdfCopy.AddDocument(new PdfReader(HttpContext.Current.Server.MapPath("/Documents/Test.pdf")));，但仍然没有乐趣。如果我注释掉pdfCopy.AddDocument(new PdfReader(HttpContext.Current.Server.MapPath("("/Documents/Test.pdf")));，我会收到错误The document has no pages。

标签： c# itext memorystream

【解决方案1】：

以下是我的问题的解决方案，我希望它对其他人有用：

public MemoryStream CreateMemoryStream()
{
    byte[] dynamicPdfBytes;

    using (var dynamicPDfMemoryStream = new MemoryStream())
    {
        using (var document = new Document(PageSize.A4, 25, 25, 30, 30))
        {
            PdfWriter.GetInstance(document, dynamicPDfMemoryStream);

            document.Open();

            var pdfPTable = new PdfPTable(1)
            {
                TotalWidth = _totalWidth,
                LockedWidth = true,
                SpacingBefore = _spacingBefore,
                SpacingAfter = _spacingAfter
            };

            float[] widths = { 272f };

            pdfPTable.SetWidths(widths);

            var image = Image.GetInstance(HttpContext.Current.Server.MapPath("/Images/logo.png"));
            image.ScaleToFit(125f, 125f);
            image.Alignment = Image.RIGHT_ALIGN;

            var pdfPCell = new PdfPCell(image)
            {
                Border = 0,
                HorizontalAlignment = Element.ALIGN_RIGHT
            };

            pdfPTable.AddCell(pdfPCell);

            document.Add(pdfPTable);
        }

        dynamicPdfBytes = dynamicPDfMemoryStream.ToArray();
    }

    byte[] pdfBytes;

    using (var pdfReader = new PdfReader(HttpContext.Current.Server.MapPath("/Documents/Test.pdf")))
    {
        using (var pdfMemoryStream = new MemoryStream())
        {
            var pdfStamper = new PdfStamper(pdfReader, pdfMemoryStream);

            var acroFields = pdfStamper.AcroFields;
            acroFields.SetField("TestField", "This is a test");
            pdfStamper.FormFlattening = true;
            pdfStamper.Close();

            pdfBytes = pdfMemoryStream.ToArray();
        }
    }

    var files = new List<byte[]> { dynamicPdfBytes, pdfBytes };

    byte[] array;

    using (var arrayMemoryStream = new MemoryStream())
    {
        var document = new Document(PageSize.A4, 25, 25, 30, 30);

        var pdfWriter = PdfWriter.GetInstance(document, arrayMemoryStream);

        document.Open();

        var directContent = pdfWriter.DirectContent;

        foreach (var bytes in files)
        {
            var pdfReader = new PdfReader(bytes);

            var numberOfPages = pdfReader.NumberOfPages;

            for (var i = 1; i <= numberOfPages; i++)
            {
                document.NewPage();

                var page = pdfWriter.GetImportedPage(pdfReader, i);

                directContent.AddTemplate(page, 0, 0);
            }
        }

        document.Close();

        array = arrayMemoryStream.ToArray();
    }

    var memoryStream = new MemoryStream();
    memoryStream.Write(array, 0, array.Length);
    memoryStream.Position = 0;

    return memoryStream;
}

【讨论】：