Users of this module and the Java FFI, on desktop computers, must define three environment variables:
JAVA_HOME points to the installation folder of the target Java VM.
This folder should contain the JNI header file include/jni.h.
e.g. /usr/lib/jvm/default-java on Debian Jessie.JNI_LIB_PATH points to the folder with libjvm.so.
e.g. /usr/lib/jvm/default-java/jre/lib/amd64/server/ on Debian Jessie.LD_LIBRARY_PATH has the path to the folder with libjvm.so.
It's the same value as JNI_LIB_PATH but LD_LIBRARY_PATH is a colon separated list
which may contain other paths.See: http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/jniTOC.html