JAVAでPDFドキュメントのコレクションを（サーバー側で）1つの大きなPDFドキュメントにマージする最も簡単な方法は何ですか

@JD OConal、ヒントをありがとう、私に送った記事は非常に古くなりましたが、それは私をiTextに向かわせました。私が必要とするものを正確に行う方法を説明するこのページを見つけました：http : //java-x.blogspot.com/2006/11/merge-pdf-files-with-itext.html

他の回答に感謝しますが、回避できる場合は他のプロセスを生成する必要はありません。プロジェクトにはすでにitext.jarがあるため、外部依存関係を追加しません。

これが私が書いたコードです：

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();
            }
        }
    }
}