将Pdf拆分为页面时iText7上的PDFEException

Question

下一段代码应该将一个多页pdf文件拆分为每页一个文件。它适用于第一页，但当关闭第二页的目标pdfDocument时，它会抛出iText。内核PDFEException:“文档没有页面。”尝试使用不同的源文件，结果相同。还尝试先获取页面数，然后打开每个页面的读卡器，得到相同的结果

Shared Function splitFileIntoPages(sourceFilename As String) As Boolean
    If System.IO.File.Exists(sourceFilename) Then

        Using reader As New PdfReader(sourceFilename)
            Using pdfSource As New PdfDocument(reader)
                For iPage = 1 To pdfSource.GetNumberOfPages
                    Dim destFilename = sourceFilename.Replace(".pdf", String.Format(".Page {0}.pdf", iPage))
                    Using writer As New PdfWriter(destFilename)
                        Using pdfDest As New PdfDocument(writer)
                            pdfSource.CopyPagesTo(iPage, 1, pdfDest)
                        End Using
                    End Using
                Next
            End Using
        End Using

    End If
    Return True
End Function

Answer 1

关键是从PdfSplitter继承并重载方法GetNextPdfWriter，以便为结果文件提供自定义文件名：

Class CustomSplitter
    Inherits PdfSplitter

    Private _pageIdx As Integer
    Private ReadOnly _sourceFilename As String

    Shared Function splitFileIntoPages(sourceFilename As String) As Boolean
        If System.IO.File.Exists(sourceFilename) Then
            Dim destinationFolder = System.IO.Path.GetDirectoryName(sourceFilename)
            Using pdfSource As New PdfDocument(New PdfReader(sourceFilename))
                Dim oSplitter = New CustomSplitter(pdfSource, sourceFilename)
                Dim oSplittedDocs = oSplitter.SplitByPageCount(1)

                For Each oSplittedDoc In oSplittedDocs
                    oSplittedDoc.Close()
                Next
            End Using
        End If
        Return True
    End Function

    Public Sub New(ByVal pdfDocument As PdfDocument, ByVal sourceFilename As String)
        MyBase.New(pdfDocument)
        _sourceFilename = sourceFilename
        _pageIdx = 0
    End Sub

    Protected Overrides Function GetNextPdfWriter(ByVal documentPageRange As PageRange) As PdfWriter
        _pageIdx += 1
        Dim filename = _sourceFilename.Replace(".pdf", String.Format(".Page {0}.pdf", _pageIdx))
        Return New PdfWriter(filename)
    End Function
End Class

用法：

CustomSplitter.splitFileIntoPages("mysourcefile.pdf")