Java Device I/O library that is portable across Single Board Computers and microcontrollers. Tested with Raspberry Pi, Odroid C2, BeagleBone Black, Next Thing CHIP, Asus Tinker Board and Arduinos / Pico. Supports GPIO, I2C, SPI as well as Serial communication. Also known to work with Udoo Quad.
The parallel configuration is pretty bunk (I haven't run it for extended period of time, like hours), so this is probably not really all that good an idea.
This can be a little difficult to set up, so cribbed the configuration setups from the sampleapps since they (obviously) were intended to work.