使用IText 2.1.7合并大型PDF

我就是这样做的:

private byte[] mergePDFs(List<byte[]> pdfBytesList) throws DocumentException, IOException {
    Document document = new Document();
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    PdfCopy copy = new PdfCopy(document, outputStream);
    document.open();

    for (byte[] pdfByteArray : pdfBytesList) {
        ByteArrayInputStream readerStream = new ByteArrayInputStream(pdfByteArray);
        PdfReader reader = new PdfReader(readerStream);

        for (int i = 0; i < reader.getNumberOfPages(); ) {
            copy.addPage(copy.getImportedPage(reader, ++i));
        }

        copy.freeReader(reader);
        reader.close();
    }

    document.close();

    return outputStream.toByteArray();
}