Segregating the read-only and read-write in Spring/J2EE Apps

We using Spring, Spring-Data and JPA in our project.

For production servers, we would like to setup database cluster such that all read queries are directed to one server and all write queries are directed to another server.

This obviously will require some changes in the way the DAOs are built.

Does anyone know how to achieve this if one has, so far, been following cook-book style DAO creations using Spring-Data/JPA where a DAO implementation is responsible for both reads and writes? What kind of changes in architecture will be needed to segregate the two types of calls?