The easiest way to combine (on the server side) a collection of PDF documents into one large PDF document in JAVA

Question

I have 3 PDF documents that are generated on the fly by the heritage library that we use and burn to disk. The easiest way for my JAVA server code to capture these 3 documents and turn them into one long PDF document, where there are only all pages from document # 1, followed by all pages from document # 2, etc.

Ideally, I would like this to happen in memory, so I can return it as a stream to the client, but also write it to disk.

Answer 1

@JD OConal, thanks for the help, the article you sent me was very outdated, but it pointed me to iText. I found this page that explains how to do exactly what I need: http://java-x.blogspot.com/2006/11/merge-pdf-files-with-itext.html

Thanks for the other answers, but I really do not want to start other processes if I can avoid this and our project already has itext.jar, so I am not adding any external dependencies

Here is the code I wrote:

public class PdfMergeHelper { /** * Merges the passed in PDFs, in the order that they are listed in the java.util.List. * Writes the resulting PDF out to the OutputStream provided. * * Sample Usage: * List<InputStream> pdfs = new ArrayList<InputStream>(); * pdfs.add(new FileInputStream("/location/of/pdf/OQS_FRSv1.5.pdf")); * pdfs.add(new FileInputStream("/location/of/pdf/PPFP-Contract_Genericv0.5.pdf")); * pdfs.add(new FileInputStream("/location/of/pdf/PPFP-Quotev0.6.pdf")); * FileOutputStream output = new FileOutputStream("/location/to/write/to/merge.pdf"); * PdfMergeHelper.concatPDFs(pdfs, output, true); * * @param streamOfPDFFiles the list of files to merge, in the order that they should be merged * @param outputStream the output stream to write the merged PDF to * @param paginate true if you want page numbers to appear at the bottom of each page, false otherwise */ public static void concatPDFs(List<InputStream> streamOfPDFFiles, OutputStream outputStream, boolean paginate) { Document document = new Document(); try { List<InputStream> pdfs = streamOfPDFFiles; 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 2

I used pdftk for a great effect. This is an external application that you will need to run from your java application.

Answer 3

iText seems to have changed and now has commercial licensing requirements, as well as not very good help (Want documentation? Buy our book!).

We ended the search for PDFSharp http://www.pdfsharp.net/ and with the help of this. The sample to combine multiple PDFs together is simple and easy to use: http://www.pdfsharp.net/wiki/ConcatenateDocuments-sample.ashx

Enjoy Random

Answer 4

Take a look at this list of Java open source PDF libraries .

Also check out this article .

[Edit: There is always Ghostscript that is easy to use, but who wants more dependencies?]

Answer 5

iText PdfCopy

Answer 6

PDFBox is by far the easiest way to achieve this, the code has a utility called PDFMerger that makes things very easy, all I needed was a loop cycle and 2 lines of code in it and everything was done :)