examples/injection-of-entitymanager/README.adoc - tomee - Git at Google

 = Injection Of Entitymanager
 :index-group: JPA
 :jbake-type: page
 :jbake-status: published

 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.

 [source,java]
 ----
 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;
     }
 }
 ----

 == 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.

 [source,xml]
 ----
 <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.

 [source,java]
 ----
 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 link:../../jpa-concepts.html[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.

 [source,java]
 ----
 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.

 [source,console]
 ----
 -------------------------------------------------------
  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
 ----
	= Injection Of Entitymanager
	:index-group: JPA
	:jbake-type: page
	:jbake-status: published

	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.

	[source,java]
	----
	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;
	}
	}
	----

	== 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.

	[source,xml]
	----
	<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.

	[source,java]
	----
	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 link:../../jpa-concepts.html[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.

	[source,java]
	----
	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.

	[source,console]
	----
	-------------------------------------------------------
	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
	----