[java] Is the buildSessionFactory() Configuration method deprecated in Hibernate

TL;DR

Yes, it is. There are better ways to bootstrap Hibernate, like the following ones.

Hibernate-native bootstrap

The legacy Configuration object is less powerful than using the BootstrapServiceRegistryBuilder, introduced since Hibernate 4:

final BootstrapServiceRegistryBuilder bsrb = new BootstrapServiceRegistryBuilder()
    .enableAutoClose();

Integrator integrator = integrator();
if (integrator != null) {
    bsrb.applyIntegrator( integrator );
}

final BootstrapServiceRegistry bsr = bsrb.build();

final StandardServiceRegistry serviceRegistry = 
    new StandardServiceRegistryBuilder(bsr)
        .applySettings(properties())
        .build();

final MetadataSources metadataSources = new MetadataSources(serviceRegistry);

for (Class annotatedClass : entities()) {
    metadataSources.addAnnotatedClass(annotatedClass);
}

String[] packages = packages();
if (packages != null) {
    for (String annotatedPackage : packages) {
        metadataSources.addPackage(annotatedPackage);
    }
}

String[] resources = resources();
if (resources != null) {
    for (String resource : resources) {
        metadataSources.addResource(resource);
    }
}

final MetadataBuilder metadataBuilder = metadataSources.getMetadataBuilder()
    .enableNewIdentifierGeneratorSupport(true)
    .applyImplicitNamingStrategy(ImplicitNamingStrategyLegacyJpaImpl.INSTANCE);

final List<Type> additionalTypes = additionalTypes();
if (additionalTypes != null) {
    additionalTypes.stream().forEach(type -> {
        metadataBuilder.applyTypes((typeContributions, sr) -> {
            if(type instanceof BasicType) {
                typeContributions.contributeType((BasicType) type);
            } else if (type instanceof UserType ){
                typeContributions.contributeType((UserType) type);
            } else if (type instanceof CompositeUserType) {
                typeContributions.contributeType((CompositeUserType) type);
            }
        });
    });
}

additionalMetadata(metadataBuilder);

MetadataImplementor metadata = (MetadataImplementor) metadataBuilder.build();

final SessionFactoryBuilder sfb = metadata.getSessionFactoryBuilder();
Interceptor interceptor = interceptor();
if(interceptor != null) {
    sfb.applyInterceptor(interceptor);
}

SessionFactory sessionFactory = sfb.build();

JPA bootstrap

You can also bootstrap Hibernate using JPA:

PersistenceUnitInfo persistenceUnitInfo = persistenceUnitInfo(getClass().getSimpleName());
Map configuration = properties();

Interceptor interceptor = interceptor();
if (interceptor != null) {
    configuration.put(AvailableSettings.INTERCEPTOR, interceptor);
}

Integrator integrator = integrator();
if (integrator != null) {
    configuration.put(
        "hibernate.integrator_provider", 
        (IntegratorProvider) () -> Collections.singletonList(integrator));
}

EntityManagerFactoryBuilderImpl entityManagerFactoryBuilder = 
    new EntityManagerFactoryBuilderImpl(
        new PersistenceUnitInfoDescriptor(persistenceUnitInfo), 
        configuration
);
EntityManagerFactory entityManagerFactory = entityManagerFactoryBuilder.build();

This way, you are building the EntityManagerFactory instead of a SessionFactory. However, the SessionFactory extends the EntityManagerFactory, so the actual object that's built is aSessionFactoryImpl` too.

Conclusion

These two bootstrapping methods affect Hibernate behavior. When using the native bootstrap, Hibernate behaves in the legacy mode, which predates JPA.

When bootstrapping using JPA, Hibernate will behave according to the JPA specification.

There are several differences between these two modes:

• How the AUTO flush mode works in regards to native SQL queries
• How the entity Proxy is built. Traditionally, Hibernate did not hit the DB when building a Proxy, but JPA requires throwing an EntityNotFoundException, therefore demanding a DB check.
• whether you can delete a non-managed entity

For more details about these differences, check out the JpaCompliance class.