11 | Query Parameters in JPA getCountryByName(EntityManager em, String name) { TypedQuery<Country> query = em.createQuery ... Country getCountryByName(EntityManager em, String name) { TypedQuery<Country> query = em ... without parameters: public Country getCountryByName(EntityManager em, String name) { TypedQuery |
9 | SELECT clause (JPQL / Criteria API)The ability to retrieve managed entity objects is a major advantage of JPQL. For example, the following query returns Country objects that become managed by the EntityManager em: TypedQuery ... are not associated with an EntityManager and changes to them when a transaction is active are not |
9 | ObjectDB Object Database Features connections and timeout. Caching L1 entity object cache (per EntityManager). L2 shared entity data ... query on an EntityManager/PersistenceManager. Supports automatic download of created backups from |
9 | Entity Management Settings the persistence context of the EntityManager (which serves as a first level cache). The valid values ... all its EntityManager instances. The level 2 cache is disabled by specifying 0 or 0mb. The <fetch> element |
9 | JPA Metamodel API by the EntityManager's getMetamodel method (both methods are equivalent). For example, given an EntityManager, em, a Metamodel instance can be obtained by: Metamodel metamodel = em.getMetamodel |
6 | JPA Query API with an EntityManager (represented by em in the following code snippets), which serves as a factory |
2 | Step 3: Define an EJB Session Bean; import java.util.List; import javax.ejb.Stateless; import javax.persistence.EntityManager; import ... class GuestDao { // Injected database connection: @PersistenceContext private EntityManager ... ). Prepares an EntityManager automatically and injects it into the em field (because it is annotated |
2 | Step 3: Define an EJB Session Bean.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.TypedQuery ... : @PersistenceContext private EntityManager em; // Stores a new guest: public void persist(Guest guest ... shown in the next step). Prepares an EntityManager automatically and injects it into the em field |
1 | Step 4: Add a Servlet Class = (EntityManagerFactory)getServletContext().getAttribute("emf"); EntityManager em ... the application scope attribute, and then an EntityManager (representing a database connection |
1 | Step 4: Add a Servlet Class().getAttribute("emf"); EntityManager em = emf.createEntityManager(); try ... : The EntityManagerFactory is retrieved from the application scope attribute, and then an EntityManager |
