使用iTextSharp提取文本会引发InvalidCastException

我目前正在使用iTextSharp从PDF文件中提取文本 .

有几十个PDF可以正常工作，但是其中2个PDF会在[1]处抛出一个无效的强制转换Stacktrace .

抛出此异常的代码如下（GetTextFromPage抛出的异常）：

PdfReader reader = new PdfReader(byteArray);
        PdfTextExtractor.GetTextFromPage(reader, 1, new SimpleTextExtractionStrategy());

一些额外的说明：

• Adobe Acrobat中的预检语法检查未发现任何错误 .

• 生成此错误的示例PDF位于：http://resources.mpi-inf.mpg.de/DisparityModel（论文（Adobe Acrobat PDF，6.69 MB） . ）

• 我已经尝试了LocationTextExtractionStrategy - 同样的错误 .

在Preflight旁边，如何检查PDF文件是否已损坏？或者这个错误来自哪里？

[1]

System.InvalidCastException was unhandled
  HResult=-2147467262
  Message=Unable to cast object of type 'iTextSharp.text.pdf.PdfLiteral' to type 'iTextSharp.text.pdf.PdfString'.
  Source=itextsharp
  StackTrace:
       at iTextSharp.text.pdf.DocumentFont.FillMetrics(Byte[] touni, IntHashtable widths, Int32 dw)
       at iTextSharp.text.pdf.DocumentFont.ProcessType0(PdfDictionary font)
       at iTextSharp.text.pdf.DocumentFont.Init()
       at iTextSharp.text.pdf.DocumentFont..ctor(PRIndirectReference refFont)
       at iTextSharp.text.pdf.CMapAwareDocumentFont..ctor(PRIndirectReference refFont)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.GetFont(PRIndirectReference ind)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.SetTextFont.Invoke(PdfContentStreamProcessor processor, PdfLiteral oper, List`1 operands)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.InvokeOperator(PdfLiteral oper, List`1 operands)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.ProcessContent(Byte[] contentBytes, PdfDictionary resources)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.FormXObjectDoHandler.HandleXObject(PdfContentStreamProcessor processor, PdfStream stream, PdfIndirectReference refi)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.DisplayXObject(PdfName xobjectName)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.Do.Invoke(PdfContentStreamProcessor processor, PdfLiteral oper, List`1 operands)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.InvokeOperator(PdfLiteral oper, List`1 operands)
       at iTextSharp.text.pdf.parser.PdfContentStreamProcessor.ProcessContent(Byte[] contentBytes, PdfDictionary resources)
       at iTextSharp.text.pdf.parser.PdfReaderContentParser.ProcessContent[E](Int32 pageNumber, E renderListener)
       at iTextSharp.text.pdf.parser.PdfTextExtractor.GetTextFromPage(PdfReader reader, Int32 pageNumber, ITextExtractionStrategy strategy)
       at ConsoleApplication1.Program.Main(String[] args) in e:\foobar\projects\AnalyzePDF\ConsoleApplication1\ConsoleApplication1\Program.cs:line 24
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: