iTextSharp PDF 一口气合并和添加页码

Question

我使用此代码合并文档并将页码添加到文档：

            Using stream As FileStream = New FileStream(targetPDF, FileMode.Create)
            Dim myDoc As Document
            If (ExportOption.Orientation = Global.GenerateReport.GenerateReport.Orientation.Portrait) Then
                myDoc = New Document(New iTextSharp.text.Rectangle(PAGE_WIDTH, PAGE_HEIGHT), MARGIN_LEFT, MARGIN_RIGHT, MARGIN_TOP, MARGIN_BOTTOM)
                myDoc.SetPageSize(PageSize.A4)
            Else
                myDoc = New Document(New iTextSharp.text.Rectangle(PAGE_WIDTH, PAGE_HEIGHT), MARGIN_LEFT, MARGIN_RIGHT, MARGIN_TOP, MARGIN_BOTTOM)
                myDoc.SetPageSize(PageSize.A4.Rotate())
            End If
            Dim pdfCopy As PdfCopy = New PdfCopy(myDoc, stream)
            myDoc.Open()

            Dim files() As String = Directory.GetFiles(sourceDir)
            For Each pdffile As String In files
                Dim reader As PdfReader = New PdfReader(pdffile)
                pdfCopy.AddDocument(reader)
                reader.Close()
            Next

            If (Not myDoc Is Nothing) Then
                myDoc.Close()
                pdfCopy.Close()
            End If
        End Using

        Dim bytes As Byte() = File.ReadAllBytes(targetPDF)
        Dim blackFont As iTextSharp.text.Font = FontFactory.GetFont("HELVETICA", 8, iTextSharp.text.Font.NORMAL, BaseColor.BLACK)
        Using stream As New MemoryStream()
            Dim reader As New PdfReader(bytes)
            Using stamper As New PdfStamper(reader, stream)

                Dim bottom As Single = 10.0F
                Dim left As Single = 550.0F

                Dim pages As Integer = reader.NumberOfPages
                For i As Integer = 1 To pages
                    ColumnText.ShowTextAligned(stamper.GetUnderContent(i), Element.ALIGN_RIGHT, New Phrase("Page " & i.ToString() & " of " & reader.NumberOfPages, blackFont), left, bottom, 0)
                Next
            End Using
            bytes = stream.ToArray()
        End Using
        File.WriteAllBytes(targetPDF, bytes)

如何一次完成？

关于我的情况的更多细节：我需要创建一个大文件，以正常方式代码运行几天并抛出内存不足异常，所以我将它拆分为较小的文件，它有效很好，但是页码都错了，那我就到这部分了。

Answer 1

要合并文档并同时在文档上标记内容，您可以使用 PdfCopy.PageStamp。 "iText in Action - 2nd Edition" 书中的示例 ConcatenateStamp.cs (corresponding to the java sample ConcatenateStamp.java 演示了 PdfCopy.PageStamp:

的用法

using (Document document = new Document()) {
    using (PdfCopy copy = new PdfCopy(document, OUTPUT_STREAM)) {
        document.Open();
        // reader for document 1
        PdfReader reader1 = new PdfReader(r1);
        int n1 = reader1.NumberOfPages;
        // reader for document 2
        PdfReader reader2 = new PdfReader(r2);
        int n2 = reader2.NumberOfPages;
        // initializations
        PdfImportedPage page;
        PdfCopy.PageStamp stamp;
        // Loop over the pages of document 1
        for (int i = 0; i < n1; ) {
            page = copy.GetImportedPage(reader1, ++i);
            stamp = copy.CreatePageStamp(page);
            // add page numbers
            ColumnText.ShowTextAligned(
              stamp.GetUnderContent(), Element.ALIGN_CENTER,
              new Phrase(string.Format("page {0} of {1}", i, n1 + n2)),
              297.5f, 28, 0
            );
            stamp.AlterContents();
            copy.AddPage(page);
        }

        // Loop over the pages of document 2
        for (int i = 0; i < n2; ) {
            page = copy.GetImportedPage(reader2, ++i);
            stamp = copy.CreatePageStamp(page);
            // add page numbers
            ColumnText.ShowTextAligned(
              stamp.GetUnderContent(), Element.ALIGN_CENTER,
              new Phrase(string.Format("page {0} of {1}", n1 + i, n1 + n2)),
              297.5f, 28, 0
            );
            stamp.AlterContents();
            copy.AddPage(page);
        }   
    }   
}

（示例是在 C# 中，而不是 VB 但它应该可以提供一个想法...）

Answer 2

请注意，当您没有正确处理东西时，通常会触发 iTextSharp 的 OOM，并不总是意味着您正在处理太大的文件。运行时间会将 "memory" 从 RAM 转移到磁盘，这会减慢速度但不会崩溃（当然，除非你运行磁盘 space 不足） .

对于您的第一个块，我鼓励您尽可能使用 using 模式来自动为您处理。我没有通过 VS 运行这段代码，所以它可能不是 100% 正确，但应该非常准确。

Using stream As New FileStream(targetPDF, FileMode.Create)
    Using myDoc As New Document(New iTextSharp.text.Rectangle(PAGE_WIDTH, PAGE_HEIGHT), MARGIN_LEFT, MARGIN_RIGHT, MARGIN_TOP, MARGIN_BOTTOM)

        If (ExportOption.Orientation = Global.GenerateReport.GenerateReport.Orientation.Portrait) Then
            myDoc.SetPageSize(PageSize.A4)
        Else
            myDoc.SetPageSize(PageSize.A4.Rotate())
        End If

        Using pdfCopy New PdfCopy(myDoc, stream)

            myDoc.Open()

            Dim files() As String = Directory.GetFiles(sourceDir)
            For Each pdffile As String In files
                Using reader As PdfReader = New PdfReader(pdffile)
                    pdfCopy.AddDocument(reader)
                End Using
            Next

            myDoc.Close()

        End Using
    End Using
End Using

@mkl 的解决方案向您展示了如何一次完成，这正是您所要求的，我只是想确保您知道什么时候以及如何 Dispose 事情。

iTextSharp PDF 一口气合并和添加页码

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