iText 7.1.15 'SymbolEncoding' 不是受支持的编码名称

如何解决iText 7.1.15 'SymbolEncoding' 不是受支持的编码名称

从 iTextSharp 5.5.13.2 迁移到 iText 7.1.15 后，我正在测试我的应用程序，并在从特定机构的 PDF 文档中提取文本时遇到异常。这些文件包含>；但是，iTextSharp 能够成功地从这些 PDF 文档中提取所有文本。我也在 iText 7.1.14 中重现了这个异常。

比较 itext7 和 iTextSharp 之间的 PdfEncodings 类后，似乎符号编码在那里。

由于在从同一个 PDF 中提取文本时，此异常仅发生在 iText7 上，而不发生在 iTextSharp 上，因此我认为这是一个错误。

有什么想法吗？

这是个例外：

'SymbolEncoding' is not a supported encoding name.
For information on defining a custom encoding,see the documentation for the Encoding.RegisterProvider method.
Parameter name: name ArgumentException
at System.Globalization.EncodingTable.internalGetCodePageFromName(String name)
at System.Globalization.EncodingTable.GetCodePageFromName(String name)
at iText.IO.Util.IanaEncodings.GetEncodingEncoding(String name)
at iText.IO.Util.EncodingUtil.ConvertToBytes(Char[] chars,String encoding)
at iText.IO.Font.PdfEncodings.ConvertToBytes(String text,String encoding)
at iText.IO.Font.FontEncoding.FillNamedEncoding()
at iText.IO.Font.FontEncoding.CreateFontEncoding(String baseEncoding)
at iText.Kernel.Font.PdfType1Font..ctor(PdfDictionary fontDictionary)
at iText.Kernel.Font.PdfFontFactory.CreateFont(PdfDictionary fontDictionary)
at iText.Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor.GetFont(PdfDictionary fontDict)
at iText.Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor.SetTextFontOperator.Invoke(PdfCanvasProcessor processor,PdfLiteral operator,IList`1 operands)
at iText.Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor.InvokeOperator(PdfLiteral operator,IList`1 operands)
at iText.Kernel.Pdf.Canvas.Parser.PdfCanvasProcessor.ProcessContent(Byte[] contentBytes,PdfResources resources)
at PDFKeeper.WindowsApplication.PdfFileInfo.GetText()
at PDFKeeper.WindowsApplication.UploadService.UploadStagedPdfsAndSupplementalData()
at PDFKeeper.WindowsApplication.UploadService.ExecuteUploadCycle()
at System.Threading.Tasks.Task.Execute()

这是我使用 iText7 的应用程序的功能：

Public Function GetText() As String
    Using reader = New PdfReader(fileInfo.FullName)
        Dim textString As New StringBuilder
        Using pdfDoc As New PdfDocument(reader)
            For page As Integer = 1 To pdfDoc.GetNumberOfPages
                Dim strategy As ITextExtractionStrategy = New LocationTextExtractionStrategy
                Dim pageText As String = PdfTextExtractor.GetTextFromPage(pdfDoc.GetPage(page),strategy)
                Dim lines As String() = pageText.Split(ControlChars.Lf)
                For Each line In lines
                    textString.AppendLine(line)
                Next
            Next
        End Using
        Return textString.ToString
    End Using
End Function

这与使用 iTextSharp 时的功能相同：

Public Function GetText() As String
    Using reader = New PdfReader(fileInfo.FullName)
        Dim textString As New StringBuilder
        For page As Integer = 1 To reader.NumberOfPages
            Try
                Dim strategy As ITextExtractionStrategy = New LocationTextExtractionStrategy
                Dim pageText As String = PdfTextExtractor.GetTextFromPage(reader,page,strategy)
                Dim lines As String() = pageText.Split(ControlChars.Lf)
                For Each line In lines
                    textString.AppendLine(line)
                Next
            Catch ex As InlineImageParseException
            End Try
        Next
        Return textString.ToString
    End Using
End Function