Enterprise JavaBeans, 3.0

5.1. Entities Are POJOs Entities, in the Java Persistence specification, are plain old Java objects (POJOs). You allocate them with the new( ) operator just as you would any other plain Java object. Instances of an entity bean class do not...

5.2. Managed Versus Unmanaged Entities Before we can go any deeper into the entity manager service, we need to delve more deeply into the life cycle of entity object instances. An entity bean instance is either managed (a.k.a. attached)...

5.3. Packaging a Persistence Unit An EntityManager maps a fixed set of classes to a particular database. This set of classes is called a persistence unit . Before you can even thin...

5.4. Obtaining an EntityManager Now that you have packaged and deployed your persistence units, you need to obtain access to an EntityManager so that you can persist, update, remove, and query your entity beans within your databases. In Ja...

5.5. Interacting with an EntityManager Now that you have learned how to deploy and obtain a reference to an entity manager, you are ready to learn the semantics of interacting with it. The EntityManager API has methods to insert and remove enti...