Java EE 6 Web Profile Without the App Server. Part 3.

beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://java.sun.com/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/beans_1_0.xsd">
   <interceptors>
      <class>com.lifeasageek.goodstuffexample.cdi.TransactionInterceptor</class>
      <class>com.lifeasageek.goodstuffexample.cdi.GoodInterceptor</class>
   </interceptors>
</beans>

Deed.java

@Entity
public class Deed implements Serializable
{
   @Id
   @GeneratedValue(strategy = GenerationType.AUTO)
   private Integer id;
   @Column
   private String altruist;
   @Column
   private String recipient;

   public Deed()
   {
   }

   public Deed(String altruist, String recipient)
   {
      this.altruist = altruist;
      this.recipient = recipient;
   }

   // Getters and setters...
}

EntityManagerProducer.java

@ApplicationScoped
public class EntityManagerProducer
{
   private static EntityManagerFactory emf;
   
   private static ThreadLocal<Stack<EntityManager>> threadEntityManagers = new ThreadLocal<>();
   
   public void register(boolean requireNew)
   {
      if (emf == null)
      {
         emf = Persistence.createEntityManagerFactory("goodstuff");
      }
      if (threadEntityManagers.get() == null)
      {
         threadEntityManagers.set(new Stack<EntityManager>());
      }
      Stack<EntityManager> emStack = threadEntityManagers.get();
      if (emStack.isEmpty())
      {
         emStack.push(emf.createEntityManager());
      }
      else
      {
         EntityManager em = emStack.peek();
         EntityTransaction tx = em.getTransaction();
         if (tx.isActive() && requireNew)
         {
            emStack.push(emf.createEntityManager());
         }
      }
   }
   
   public EntityManager get()
   {
      Stack<EntityManager> emStack = threadEntityManagers.get();
      if (emStack == null || emStack.isEmpty())
      {
         register(false);
         emStack = threadEntityManagers.get();
      }
      EntityManager em = emStack.peek();
      return em;
   }
   
   public void unregister(EntityManager em)
   {
      Stack<EntityManager> emStack = threadEntityManagers.get();
      emStack.remove(em);
   }    
}

EntityManagerWrapper.java

public class EntityManagerWrapper implements EntityManager
{
   @Inject
   private EntityManagerProducer emp;

   @Override
   public void persist(Object entity)
   {
      emp.get().persist(entity);
   }

   // All methods wrapped.
}

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
  <persistence-unit name="goodstuff" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:goodstuff"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.show_sql" value="false"/>
    </properties>
  </persistence-unit>
</persistence>

pom.xml

<dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-entitymanager</artifactId>
   <version>4.0.0.Final</version>
</dependency>
<dependency>
   <groupId>com.h2database</groupId>
   <artifactId>h2</artifactId>
   <version>1.3.160</version>
</dependency>

Transactional.java

@InterceptorBinding
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Transactional
{
}

TransactionInterceptor.java

@Transactional
@Interceptor
public class TransactionInterceptor
{
   @Inject
   private EntityManagerProducer emp;
   private boolean owner = false;
   private EntityTransaction tx;
   
   @AroundInvoke 
   public Object manageTransaction(InvocationContext ctx) throws Exception
   {
      emp.register(false);
      EntityManager em = emp.get();
      em.setFlushMode(FlushModeType.COMMIT);
      tx = em.getTransaction();
      try
      {
         if (!tx.isActive())
         {
            tx.begin();
            owner = true;
         }
         Object result = ctx.proceed();
         if (tx.isActive() && owner)
         {
            tx.commit();
         }
         return result;
      }
      catch (Exception ex)
      {
         if (tx.isActive() && !owner)
         {
            tx.setRollbackOnly();
         }
         if (tx.isActive() && owner)
         {
            tx.rollback();
         }
         throw ex;
      }
      finally
      {
         try
         {
            if (tx.isActive() && tx.getRollbackOnly() && owner)
            {
                tx.rollback();
            }
         }
         catch (Exception ex)
         {
             // Something is horribly wrong!
             ex.printStackTrace();
         }
         finally
         {
            if (owner)
            {
                emp.unregister(em);
                em.close();
            }
         }
      }
   }
}