Pattern to seprate DAO layer from Service layer

I am working on a project where we are currently using hibernate. I want to find a way to code the project so as we can easily remove the hibernate and replace it with something else (e.g. jdbc) in future.

I found bits and pieces about a using a mapper but did not completely grasp the foundation . Does anyone know of a good example implementing a design pattern(to show my boss) that does something like this currently.

We are currently coding in java so a java example would be amazing.