POJO's are becoming even more prevalent with the appearance of EJB 3 and the Java Persistence API -- TSS Asks: POJO as Lingua Franca for persistence?. In this blog entry, Debu Panda discusses Oracle’s extension for managed POJOs and describes how to use dependency injection such as @Resource or @PersistenceContext with regular POJOs
Java EE 5 greatly simplifies using resources and EJBs by using dependency injection. However this support limits only to managed classes such as EJBs, Interceptors, Servlets, etc. Many applications use helper classes those are regular POJOs. However Java EE 5 / EJB 3 does not require support of dependency injection with regular POJOs or injecting POJOs into managed classes... This example has a session bean named EmployeeFacade that injects a regular POJO named EmployeeHelper. The EmployeeHelper POJO uses @PersistenceContext to inject an instance of EntityManager.
Read the complete post : Injecting POJOs and using resource injection in POJOs