associating a file with a specific version of java when i have multiple versions

I am trying to associate a jnlp file with a specific version of java when i have multiple on my Mac Pro. I need all versions due to other applications only working with certain versions. Every time I try to launch this specific jnlp file it always tries to launch using an older version of java (7) which it is not capable of running on. I am trying to associate it with the newest version (8). please help.