檢查PDF文檔在C＃中是否爲空

Question

我們有一個C＃應用程序，它將讀取條形碼的pdf文檔，如果找到條形碼，它會將文檔上傳到IBM FileNet P8中的文件。

如果未找到條形碼，它將被移動到不同的文件夾。

現在我們還有一個來自客戶端的請求。檢查PDF是否爲空白。從某種意義上說，如果用戶掃描一個白頁並通過電子郵件發送PDF。

我需要檢查它是否爲空，如果是這樣通知用戶。

我正在使用iTextSharp。

感謝

Answer 1

com.itextpdf.text.pdf.parser.PdfContentReaderTool

http://www.java2s.com/Open-Source/CSharp/PDF/iTextSharp/iTextSharp/text/pdf/parser/PdfContentReaderTool.cs.htm

看來這將返回 'outp.WriteLine（+頁次 「無正文頁上」）;' 所有頁面或0/1 :)

我認爲這可以幫助你...希望。

CODE 
namespace iTextSharp.text.pdf.parser{ 

    /** 
    * Tool that parses the content of a PDF document. 
    * @since 2.1.4 
    */ 
    public class PdfContentReaderTool { 

     /** 
     * Shows the detail of a dictionary. 
     * This is similar to the PdfLister functionality. 
     * @param dic the dictionary of which you want the detail 
     * @return a String representation of the dictionary 
     */ 
     public static String GetDictionaryDetail(PdfDictionary dic){ 
      return GetDictionaryDetail(dic, 0); 
     } 

     /** 
     * Shows the detail of a dictionary. 
     * @param dic the dictionary of which you want the detail 
     * @param depth the depth of the current dictionary (for nested dictionaries) 
     * @return a String representation of the dictionary 
     */ 
     public static String GetDictionaryDetail(PdfDictionary dic, int depth){ 
      StringBuilder builder = new StringBuilder(); 
      builder.Append('('); 
      IList<PdfName> subDictionaries = new List<PdfName>(); 
      foreach (PdfName key in dic.Keys) { 
       PdfObject val = dic.GetDirectObject(key); 
       if (val.IsDictionary()) 
        subDictionaries.Add(key); 
       builder.Append(key); 
       builder.Append('='); 
       builder.Append(val); 
       builder.Append(", "); 
      } 
      builder.Length = builder.Length-2; 
      builder.Append(')'); 
      foreach (PdfName pdfSubDictionaryName in subDictionaries) { 
       builder.Append('\n'); 
       for (int i = 0; i < depth+1; i++){ 
        builder.Append('\t'); 
       } 
       builder.Append("Subdictionary "); 
       builder.Append(pdfSubDictionaryName); 
       builder.Append(" = "); 
       builder.Append(GetDictionaryDetail(dic.GetAsDict(pdfSubDictionaryName), depth+1)); 
      } 
      return builder.ToString(); 
     } 

     /** 
     * Displays a summary of the entries in the XObject dictionary for the stream 
     * @param resourceDic the resource dictionary for the stream 
     * @return a string with the summary of the entries 
     * @throws IOException 
     * @since 5.0.2 
     */ 
     public static String GetXObjectDetail(PdfDictionary resourceDic) { 
      StringBuilder sb = new StringBuilder(); 

      PdfDictionary xobjects = resourceDic.GetAsDict(PdfName.XOBJECT); 
      if (xobjects == null) 
       return "No XObjects"; 
      foreach (PdfName entryName in xobjects.Keys) { 
       PdfStream xobjectStream = xobjects.GetAsStream(entryName); 

       sb.Append("------ " + entryName + " - subtype = " + xobjectStream.Get(PdfName.SUBTYPE) + " = " + xobjectStream.GetAsNumber(PdfName.LENGTH) + " bytes ------\n"); 

       if (!xobjectStream.Get(PdfName.SUBTYPE).Equals(PdfName.IMAGE)){ 

        byte[] contentBytes = ContentByteUtils.GetContentBytesFromContentObject(xobjectStream); 

        foreach (byte b in contentBytes) { 
         sb.Append((char)b); 
        } 

        sb.Append("------ " + entryName + " - subtype = " + xobjectStream.Get(PdfName.SUBTYPE) + "End of Content" + "------\n"); 
       } 
      } 

      return sb.ToString(); 
     } 

     /** 
     * Writes information about a specific page from PdfReader to the specified output stream. 
     * @since 2.1.5 
     * @param reader the PdfReader to read the page content from 
     * @param pageNum the page number to read 
     * @param out  the output stream to send the content to 
     * @throws IOException 
     */ 
     public static void ListContentStreamForPage(PdfReader reader, int pageNum, TextWriter outp) { 
      outp.WriteLine("==============Page " + pageNum + "===================="); 
      outp.WriteLine("- - - - - Dictionary - - - - - -"); 
      PdfDictionary pageDictionary = reader.GetPageN(pageNum); 
      outp.WriteLine(GetDictionaryDetail(pageDictionary)); 

      outp.WriteLine("- - - - - XObject Summary - - - - - -"); 
      outp.WriteLine(GetXObjectDetail(pageDictionary.GetAsDict(PdfName.RESOURCES))); 

      outp.WriteLine("- - - - - Content Stream - - - - - -"); 
      RandomAccessFileOrArray f = reader.SafeFile; 

      byte[] contentBytes = reader.GetPageContent(pageNum, f); 
      f.Close(); 

      outp.Flush(); 

      foreach (byte b in contentBytes) { 
       outp.Write((char)b); 
      } 

      outp.Flush(); 

      outp.WriteLine("- - - - - Text Extraction - - - - - -"); 
      String extractedText = PdfTextExtractor.GetTextFromPage(reader, pageNum, new LocationTextExtractionStrategy()); 
      if (extractedText.Length != 0) 
       outp.WriteLine(extractedText); 
      else 
       outp.WriteLine("No text found on page " + pageNum); 

      outp.WriteLine(); 

     } 

     /** 
     * Writes information about each page in a PDF file to the specified output stream. 
     * @since 2.1.5 
     * @param pdfFile a File instance referring to a PDF file 
     * @param out  the output stream to send the content to 
     * @throws IOException 
     */ 
     public static void ListContentStream(string pdfFile, TextWriter outp) { 
      PdfReader reader = new PdfReader(pdfFile); 

      int maxPageNum = reader.NumberOfPages; 

      for (int pageNum = 1; pageNum <= maxPageNum; pageNum++){ 
       ListContentStreamForPage(reader, pageNum, outp); 
      } 

     } 

     /** 
     * Writes information about the specified page in a PDF file to the specified output stream. 
     * @since 2.1.5 
     * @param pdfFile a File instance referring to a PDF file 
     * @param pageNum the page number to read 
     * @param out  the output stream to send the content to 
     * @throws IOException 
     */ 
     public static void ListContentStream(string pdfFile, int pageNum, TextWriter outp) { 
      PdfReader reader = new PdfReader(pdfFile); 

      ListContentStreamForPage(reader, pageNum, outp); 
     } 

     /** 
     * Writes information about each page in a PDF file to the specified file, or System.out. 
     * @param args 
     */ 
     public static void Main(String[] args) { 
      try{ 
       if (args.Length < 1 || args.Length > 3){ 
        Console.WriteLine("Usage: PdfContentReaderTool <pdf file> [<output file>|stdout] [<page num>]"); 
        return; 
       } 

       TextWriter writer = Console.Out; 
       if (args.Length >= 2){ 
        if (!Util.EqualsIgnoreCase(args[1], "stdout")) { 
         Console.WriteLine("Writing PDF content to " + args[1]); 
         writer = new StreamWriter(args[1]); 
        } 
       } 

       int pageNum = -1; 
       if (args.Length >= 3){ 
        pageNum = int.Parse(args[2]); 
       } 

       if (pageNum == -1){ 
        ListContentStream(args[0], writer); 
       } else { 
        ListContentStream(args[0], pageNum, writer); 
       } 
       writer.Flush(); 

       if (args.Length >= 2){ 
        writer.Close(); 
        Console.WriteLine("Finished writing content to " + args[1]); 
       } 
      } catch (Exception e){ 
       Console.WriteLine(e.ToString()); 
      } 
     } 
    } 
} 
/CODE