How to run Platform 1.9.9 with Java 8?

Hello All, Is it possible that I can run openMRS V1.9.9 (all-in-one standalone or enterprise war) in Java 8. When I tried to run all-in-one standalone V1.9.9, I got error & it said it was compiled in Java6 environment. If it is possible, how do I achieve running V1.9.9 in Java 8. Would recompiling the source in Java 8 environment work? If it does, where can I look for the source? I can only find the enterprise WAR & standalone pre-compiled module for V1.9.9. Thanks in advance.