Sample java code to convert files to QR Codes and display them, also sample code to read QR Codes in sequence and convert back to a file.
See a write up at http://volumeLabs.net/air-gap/
Some code copied from https://github.com/zxing/zxing. Uses libraries from https://github.com/zxing/zxing