This example shows use of @PersistenceContext
to have an EntityManager
with an
EXTENDED
persistence context injected into a @Stateful bean
. A JPA
@Entity
bean is used with the EntityManager
to create, persist and merge
data to a database.
The entity itself is simply a pojo annotated with @Entity
. We create one called Movie
which we can use to hold movie records.
package org.superbiz.injection.jpa; import javax.persistence.Entity; @Entity public class Movie { @Id @GeneratedValue private long id; private String director; private String title; private int year; public Movie() { } public long getId() { return id; } public void setId(long id) { this.id = id; } public Movie(String director, String title, int year) { this.director = director; this.title = title; this.year = year; } public String getDirector() { return director; } public void setDirector(String director) { this.director = director; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public int getYear() { return year; } public void setYear(int year) { this.year = year; } }
The above Movie
entity can be created, removed, updated or deleted via an EntityManager
object. The EntityManager
itself is
configured via a META-INF/persistence.xml
file that is placed in the same jar as the Movie
entity.
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0"> <persistence-unit name="movie-unit"> <jta-data-source>movieDatabase</jta-data-source> <non-jta-data-source>movieDatabaseUnmanaged</non-jta-data-source> <class>org.superbiz.injection.jpa.Movie</class> <properties> <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)"/> </properties> </persistence-unit> </persistence>
Notice that the Movie
entity is listed via a <class>
element. This is not required, but can help when testing or when the
Movie
class is located in a different jar than the jar containing the persistence.xml
file.
The EntityManager
itself is created by the container using the information in the persistence.xml
, so to use it at
runtime, we simply need to request it be injected into one of our components. We do this via @PersistenceContext
The @PersistenceContext
annotation can be used on any CDI bean, EJB, Servlet, Servlet Listener, Servlet Filter, or JSF ManagedBean. If you don’t use an EJB you will need to use a UserTransaction
begin and commit transactions manually. A transaction is required for any of the create, update or delete methods of the EntityManager to work.
package org.superbiz.injection.jpa; import javax.ejb.Stateful; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.PersistenceContextType; import javax.persistence.Query; import java.util.List; @Stateful public class Movies { @PersistenceContext(unitName = "movie-unit", type = PersistenceContextType.EXTENDED) private EntityManager entityManager; public void addMovie(Movie movie) throws Exception { entityManager.persist(movie); } public void deleteMovie(Movie movie) throws Exception { entityManager.remove(movie); } public List<Movie> getMovies() throws Exception { Query query = entityManager.createQuery("SELECT m from Movie as m"); return query.getResultList(); } }
This particular EntityManager
is injected as an EXTENDED
persistence context, which simply means that the EntityManager
is created when the @Stateful
bean is created and destroyed when the @Stateful
bean is destroyed. Simply put, the
data in the EntityManager
is cached for the lifetime of the @Stateful
bean.
The use of EXTENDED
persistence contexts is only available to @Stateful
beans. See the JPA Concepts page for an high level explanation of what a "persistence context" really is and how it is significant to JPA.
Testing JPA is quite easy, we can simply use the EJBContainer
API to create a container in our test case.
package org.superbiz.injection.jpa; import junit.framework.TestCase; import javax.ejb.embeddable.EJBContainer; import javax.naming.Context; import java.util.List; import java.util.Properties; //START SNIPPET: code public class MoviesTest extends TestCase { public void test() throws Exception { final Properties p = new Properties(); p.put("movieDatabase", "new://Resource?type=DataSource"); p.put("movieDatabase.JdbcDriver", "org.hsqldb.jdbcDriver"); p.put("movieDatabase.JdbcUrl", "jdbc:hsqldb:mem:moviedb"); final Context context = EJBContainer.createEJBContainer(p).getContext(); Movies movies = (Movies) context.lookup("java:global/injection-of-entitymanager/Movies"); movies.addMovie(new Movie("Quentin Tarantino", "Reservoir Dogs", 1992)); movies.addMovie(new Movie("Joel Coen", "Fargo", 1996)); movies.addMovie(new Movie("Joel Coen", "The Big Lebowski", 1998)); List<Movie> list = movies.getMovies(); assertEquals("List.size()", 3, list.size()); for (Movie movie : list) { movies.deleteMovie(movie); } assertEquals("Movies.getMovies()", 0, movies.getMovies().size()); } }
When we run our test case we should see output similar to the following.
------------------------------------------------------- T E S T S ------------------------------------------------------- Running org.superbiz.injection.jpa.MoviesTest Apache OpenEJB 4.0.0-beta-1 build: 20111002-04:06 http://tomee.apache.org/ INFO - openejb.home = /Users/dblevins/examples/injection-of-entitymanager INFO - openejb.base = /Users/dblevins/examples/injection-of-entitymanager INFO - Using 'javax.ejb.embeddable.EJBContainer=true' INFO - Configuring Service(id=Default Security Service, type=SecurityService, provider-id=Default Security Service) INFO - Configuring Service(id=Default Transaction Manager, type=TransactionManager, provider-id=Default Transaction Manager) INFO - Configuring Service(id=movieDatabase, type=Resource, provider-id=Default JDBC Database) INFO - Found EjbModule in classpath: /Users/dblevins/examples/injection-of-entitymanager/target/classes INFO - Beginning load: /Users/dblevins/examples/injection-of-entitymanager/target/classes INFO - Configuring enterprise application: /Users/dblevins/examples/injection-of-entitymanager INFO - Configuring Service(id=Default Stateful Container, type=Container, provider-id=Default Stateful Container) INFO - Auto-creating a container for bean Movies: Container(type=STATEFUL, id=Default Stateful Container) INFO - Configuring Service(id=Default Managed Container, type=Container, provider-id=Default Managed Container) INFO - Auto-creating a container for bean org.superbiz.injection.jpa.MoviesTest: Container(type=MANAGED, id=Default Managed Container) INFO - Configuring PersistenceUnit(name=movie-unit) INFO - Auto-creating a Resource with id 'movieDatabaseNonJta' of type 'DataSource for 'movie-unit'. INFO - Configuring Service(id=movieDatabaseNonJta, type=Resource, provider-id=movieDatabase) INFO - Adjusting PersistenceUnit movie-unit <non-jta-data-source> to Resource ID 'movieDatabaseNonJta' from 'movieDatabaseUnmanaged' INFO - Enterprise application "/Users/dblevins/examples/injection-of-entitymanager" loaded. INFO - Assembling app: /Users/dblevins/examples/injection-of-entitymanager INFO - PersistenceUnit(name=movie-unit, provider=org.apache.openjpa.persistence.PersistenceProviderImpl) - provider time 462ms INFO - Jndi(name="java:global/injection-of-entitymanager/Movies!org.superbiz.injection.jpa.Movies") INFO - Jndi(name="java:global/injection-of-entitymanager/Movies") INFO - Jndi(name="java:global/EjbModule1461341140/org.superbiz.injection.jpa.MoviesTest!org.superbiz.injection.jpa.MoviesTest") INFO - Jndi(name="java:global/EjbModule1461341140/org.superbiz.injection.jpa.MoviesTest") INFO - Created Ejb(deployment-id=Movies, ejb-name=Movies, container=Default Stateful Container) INFO - Created Ejb(deployment-id=org.superbiz.injection.jpa.MoviesTest, ejb-name=org.superbiz.injection.jpa.MoviesTest, container=Default Managed Container) INFO - Started Ejb(deployment-id=Movies, ejb-name=Movies, container=Default Stateful Container) INFO - Started Ejb(deployment-id=org.superbiz.injection.jpa.MoviesTest, ejb-name=org.superbiz.injection.jpa.MoviesTest, container=Default Managed Container) INFO - Deployed Application(path=/Users/dblevins/examples/injection-of-entitymanager) Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.301 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0