What is the use of EntityManager in JPA?
JPA EntityManager is used to access a database in a particular application. It is used to manage persistent entity instances, to find entities by their primary key identity, and to query over all entities.Click to see full answer. Just so, how does EntityManager work in JPA?EntityManager is the primary JPA interface used by applications. Each…
JPA EntityManager is used to access a database in a particular application. It is used to manage persistent entity instances, to find entities by their primary key identity, and to query over all entities.Click to see full answer. Just so, how does EntityManager work in JPA?EntityManager is the primary JPA interface used by applications. Each EntityManager manages a set of persistent objects, and has APIs to insert new objects and delete existing ones. When used outside the container, there is a one-to-one relationship between an EntityManager and an EntityTransaction .Also, what is the use of @PersistenceContext? You can use the @PersistenceContext annotation to inject an EntityManager in an EJB 3.0 client (such as a stateful or stateless session bean, message-driven bean, or servlet). You can use @PersistenceContext without specifying a unitName attribute to use the OC4J default persistence unit, as Example 29-12 shows. Also Know, what is an EntityManager? Entity manager. The EntityManager is an API that manages the lifecycle of entity instances. An EntityManager object manages a set of entities that are defined by a persistence unit. Each EntityManager instance is associated with a persistence context.What is the use of entity manager?The EntityManager API is used to create and remove persistent entity instances, to find entities by their primary key, and to query over entities. The set of entities that can be managed by a given EntityManager instance is defined by a persistence unit.
