Following the great failure of Java EE 1.4 Enterprise JavaBean 2.x Entity Bean (Bean-Managed Persistence & Container-Managed Persistence) (now deprecated). Please, read Expert One-on-One J2EE Development without EJB to understand why EJB 1.x and 2.x has hurt so much Java EE reputation. Also watch Rod Johnson - Lessons Learned from Java EE to understand the dangers of design by committee.
I do not use any ORM tool in my Java projects as they create more problems than they try to solve. Hibernate vs JPA vs JDO - pros and cons of each?
Object-Relational mapping is the Vietnam of Computer Science
ORM is an anti-pattern
Using an ORM or plain SQL?
If you insist on using an ORM, here are two strong free implementations of the Java EE Java Persistence API (Java Persistence/What is JPA?) to choose from:
What Java ORM do you prefer, and why?
JPA Implementations - Which one is the best to use?