For some time now, our Java application has came pre bundled with a JRE on Windows. We have a little launcher app written in C that make the application use our pre bundled
Here is a step-by-step guide from Oracle themselves on how to bundle a JRE for distributing on Apple:
http://docs.oracle.com/javase/7/docs/technotes/guides/jweb/packagingAppsForMac.html