[JAVA] 여러 PDF 합치기

EX)

List pdfs = new ArrayList<InputStream>();
pdfs.add(new FileInputStream(orgFilePath));
output = new FileOutputStream(pdfPath);
Common.concatPDFs(pdfs, output, true);


import com.itextpdf.text.Document;
import com.itextpdf.text.Image;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.BaseFont;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfImportedPage;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfWriter;
import com.itextpdf.text.pdf.RandomAccessFileOrArray;
import com.itextpdf.text.pdf.codec.TiffImage;

	/**
	 * @param streamOfPDFFiles List형 PDF목록 
	 * @param outputStream 합치고난 후 PDF
	 * @param paginate
	 */
	public static void concatPDFs(List<InputStream> streamOfPDFFiles,
		OutputStream outputStream, boolean paginate) {

		Document document = new Document();
		PdfWriter writer = null;
		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
			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();
			writer.close();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (document.isOpen())
				document.close();
			try {
				if (outputStream != null)
					outputStream.close();
			} catch (IOException ioe) {
				ioe.printStackTrace();
			}
			
		}
	}