Java：iText庫PDF合併，pdf總是在頁面底部

Question

我正在使用iText庫合併個別pdf。但個人pdf總是在頁面的底部。任何指針，我可以如何使它顯示在中間或頂部。我已經調整了我的代碼http://viralpatel.net/blogs/itext-tutorial-merge-split-pdf-files-using-itext-jar/

public static void concatPDFs(OutputStream outputStream, boolean paginate) { 

     Document document = new Document(); 
     try { 
      List<InputStream> pdfs = listPdf; 
      List<PdfReader> readers = new ArrayList<PdfReader>(); 
      int totalPages = 0; 
      Iterator<InputStream> iteratorPDFs = pdfs.iterator(); 

      // Create Readers for the pdfs. 
      while (iteratorPDFs.hasNext()) { 
       InputStream pdf = iteratorPDFs.next(); 
       PdfReader pdfReader = new PdfReader(pdf); 
       readers.add(pdfReader); 
       totalPages += pdfReader.getNumberOfPages(); 
      } 
      // Create a writer for the outputstream 
      PdfWriter writer = PdfWriter.getInstance(document, outputStream); 

      document.open(); 
      BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA, 
        BaseFont.CP1252, BaseFont.NOT_EMBEDDED); 
      PdfContentByte cb = writer.getDirectContent(); // Holds the PDF 
      // data 

      PdfImportedPage page; 
      int currentPageNumber = 0; 
      int pageOfCurrentReaderPDF = 0; 
      Iterator<PdfReader> iteratorPDFReader = readers.iterator(); 

      // Loop through the PDF files and add to the output. 
      while (iteratorPDFReader.hasNext()) { 
       PdfReader pdfReader = iteratorPDFReader.next(); 

       // Create a new page in the target for each source page. 
       while (pageOfCurrentReaderPDF < pdfReader.getNumberOfPages()) { 
        document.newPage(); 
        pageOfCurrentReaderPDF++; 
        currentPageNumber++; 
        page = writer.getImportedPage(pdfReader, 
          pageOfCurrentReaderPDF); 
        cb.addTemplate(page, 0, 0); 

        // Code for pagination. 
        if (paginate) { 
         cb.beginText(); 
         cb.setFontAndSize(bf, 9); 
         cb.showTextAligned(PdfContentByte.ALIGN_CENTER, "" 
           + currentPageNumber + " of " + totalPages, 520, 
           5, 0); 
         cb.endText(); 
        } 
       } 
       pageOfCurrentReaderPDF = 0; 
      } 
      outputStream.flush(); 
      document.close(); 
      outputStream.close(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } finally { 
      if (document.isOpen()) 
       document.close(); 
      try { 
       if (outputStream != null) 
        outputStream.close(); 
      } catch (IOException ioe) { 
       ioe.printStackTrace(); 
      } 
     } 
    } 

Answer 1

首先明確了關於座標系。 PDF座標系（0，0）代表PDF頁面的左下角。

你可以計算出新的「Y」位置插入頁面模板是這樣的：

Y =新的文檔HEIGH - 導入的頁面高度

，然後你可以改變你的代碼：

cb.addTemplate(page, 0, y); 

Answer 2

合併PDF文件所能做的最好的事情是遵循iText開發者的使用說明..

https://stackoverflow.com/a/24359217/2865036

就像他說的那樣，PDF文件的格式不會改變