Persistenz und JSON APIs

// GreetingService (already defined in hello.service bundle)
public interface GreetingService {
  /** Returns a list of all available greetings. */
  Collection getGreetings() throws Exception;
  /** Adds a new greeting. */
  void sayHello(final String greeting) throws Exception;
}
// JPA Implementation of {@link GreetingService} 
public class JpaGreetingServiceImpl implements GreetingService {
  private final EntityManagerFactory emf;
  public JpaGreetingServiceImpl(EntityManagerFactory emf) {
    this. emf = emf;
  }
  public Collection getGreetings() throws Exception {
    final EntityManager em = emf.createEntityManager();
    final TypedQuery q = em.createQuery(
      "SELECT g FROM GreetingEntity g ORDER BY g.created desc", GreetingEntity.class);
    final List results = q.getResultList();
    final List greetings = new ArrayList(results.size());
    for (final GreetingEntity entity : results) {
      greetings.add(entity.getText());
    }
    em.close();
    return Collections.unmodifiableList(greetings);
  }
  public void sayHello(final String greeting) throws Exception {
    final EntityManager em = emf.createEntityManager();
    final GreetingEntity entity = new GreetingEntity();
    entity.setCreated(System.currentTimeMillis());
    entity.setText(greeting.getText());
    em.getTransaction().begin();
    em.persist(entity);
    em.getTransaction().commit();
    em.close();
  }
}

OSGI-INF/jpa-greeting-service.xml:


JpaGreetingServiceComponent.java:
public class JpaGreetingServiceComponent implements GreetingService {
  private GreetingService service;
  public void activate(final ComponentContext context) {
    final EntityManagerFactoryBuilder emfBuilder = (EntityManagerFactoryBuilder) context.locateService("EntityManagerFactoryBuilder");;
    // disable Gemini JPA/EclipseLink data source handling for NoSQL
    final Map props = new HashMap(2);
    props.put("javax.persistence.nonJtaDataSource", "");
    props.put("gemini.jpa.providerConnectedDataSource", Boolean.TRUE);
    // configure MongoDB connection
    props.put("eclipselink.target-database", "org.eclipse.persistence.nosql.adapters.mongo.MongoPlatform");
    props.put("eclipselink.nosql.connection-spec", "org.eclipse.persistence.nosql.adapters.mongo.MongoConnectionSpec");
    props.put("eclipselink.nosql.property.mongo.host", "localhost");
    props.put("eclipselink.nosql.property.mongo.db", "jpamongodb");
    // create EntityManagerFactory and service
    emf = emfBuilder.createEntityManagerFactory(props);
    service = new JpaGreetingServiceImpl(emf);
  }
  public void deactivate(final ComponentContext context) {
    emf.close(); emf = null; // close EMF
    service = null; // dispose real service
  }
  public Collection getGreetings() throws Exception {
    return getService().getGreetings();
  }
  public GreetingService getService() {
    final GreetingService greetingService = service;
    if (greetingService == null)
      throw new IllegalStateException("inactive");
    return greetingService;
  }
  public void sayHello(final String greeting) throws Exception {
    getService().sayHello(greeting);
  }
}

META-INF/MANIFEST.MF:
Manifest-Version: 1.0
Bundle-SymbolicName: hello.jpa
...
Service-Component: OSGI-INF/jpa-greeting-service.xml
Bundle-ActivationPolicy: lazy

build.properties:
bin.includes = META-INF/,
               .,
               OSGI-INF/
...