Convert images to PDF file using PDFBox

Question

I want to convert some images to PDDocument object, and not save to hardware. How to get input stream from this PDDocument object?

I wrote as below, got "Create InputStream called without data being written before to stream." error.

The part of source is:

public ByteArrayOutputStream imagesToPdf(final List<ImageEntity> images) throws IOException {
    final PDDocument doc = new PDDocument();
    
    final int count = images.size();
    InputStream in = null;
    PDPageContentStream contentStream = null;
    final ByteArrayOutputStream baos = new ByteArrayOutputStream();
    try {
        for (int i = 0; i < count; i ++) {
            final ImageEntity image = images.get(i);
            byte[] byteCode = image.getByteCode();

            in = new ByteArrayInputStream(byteCode);
            BufferedImage bi = ImageIO.read(in);

            float width = bi.getWidth();
            float height = bi.getHeight();
            PDPage page = new PDPage(new PDRectangle(width, height));
            doc.addPage(page); 

            PDImageXObject pdImage = PDImageXObject.createFromByteArray(doc, byteCode, null);
            contentStream = new PDPageContentStream(doc, page, AppendMode.APPEND, true, true);
            
            float scale = 1f;
            contentStream.drawImage(pdImage, 0, 0, pdImage.getWidth()*scale, pdImage.getHeight()*scale);
            
            IOUtils.closeQuietly(contentStream);
            IOUtils.closeQuietly(in);
        }

        PDStream ps = new PDStream(doc);
        is = ps.createInputStream();
        IOUtils.copy(is, baos);

        return baos;
    } finally {
        IOUtils.closeQuietly(contentStream);
        IOUtils.closeQuietly(in);
    }
}

Answer 1

new PDStream(doc)

does not create an object from which the doc can be retrieved in serialized form as you assume. What it actually does is create a PDF stream object belonging to the document doc.

What you want to do is simply

doc.save(baos);