Portable Persistence Using the EJB 3.0 Java Persistence API

摘要

Experience has taught us that it's not enough to simply have a persistence standard as part of an enterprise specification. It must be a standard that can solve people's problems and be useful to most of the applications that want to use it. While earlier versions of Enterprise JavaBeans (EJB) persistence met some of the needs, they were primarily focused on the distributed problem domain. It is now known, and has been proven by successful commercial products like Oracle TopLink and Open Source projects like JBoss Hibernate, that the objects to be persisted don't have to be anything more than simple Java objects. The proof was in the popularity of these Object-Relational Mapping (ORM) tools; most developers have tended to pick up and use these tools rather than adopt the Java 2 Enterprise Edition (J2EE) entity bean programming standard.