The Pi4J Project now includes support for BananaPi and BananaPro!
This support has just been added and only cursory tests performed, so lets call it experimental for now, but I welcome you guys to try it out and let me know if you run into any trouble. You must use the Pi4J v1.1-SNAPSHOT builds until v1.1 gets released. You can manually download the JARs in ZIP or the installable .DEB package from this page:
http://pi4j.com/download.html
Support includes Java programatic access and control of GPIO inputs/outputs, PWM, I2C, SPI, and UART (serial).
There is no documentation yet specifically for the Banana platforms, but apart from a few subtle differences in configuring a platform and pin/bus addressing, its basically the same. Perhaps better than documentation ... there are a number of examples (sample code) included in the build and available in the GitHub repo specific to each Banana platform:
BananaPi Examples:
https://github.com/Pi4J/pi4j/tree/develop/pi4j-example/src/main/java/bananapi
BananaPro Examples:
https://github.com/Pi4J/pi4j/tree/develop/pi4j-example/src/main/java/bananapro