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;
}
}
Injection Of Entitymanager
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.
Creating the JPA Entity
The entity itself is simply a pojo annotated with @Entity
. We create one called Movie
which we can use to hold movie records.
Configure the EntityManager via a persistence.xml file
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.
Injection via @PersistenceContext
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.
MoviesTest
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());
}
}
Running
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