- iText; nowadays iText is a commercial library, the latest version is not for free anymore (a fork of an older version remains under MIT license: OpenPDF)
- FOP; I worked a lot with FOP. It’s fairly resource intensive (Java > XML > XSLT > PDF) and complex PDFs become a nightmare ( may result in XSLTs with 20k+ LoC)
- PDFBox; it seems to be the best alternative although I did not work with it in large projects
- Did not check Flying Saucer yet
To conclude, I’d give PDFBox a try. Depending on your bar code requirements you may need to inline your barcode (font) into the PDF or distribute the font to your clients – take care of those issues.