After reading some of the posts in this website related to exactly the same issue I\'ve got, I found that none of them were giving me a successful result:
How to run a j
This is not a straight answer, but if calling java from Php does not work under any circumstances, you can also run jar files from Python scripts. I mean Php --> Python --> jar.
Calling Python scripts from Php always works for me.
This post helped me in the past:
Python: How can I execute a jar file through a python script