Hibernate Session API

Session = Hibernate EntityManager

Hibernate's own API predates JPA. Session extends EntityManager, so every JPA method works on it, plus some extras. In Spring you can get it from the EntityManager:

Session session = entityManager.unwrap(Session.class);

session.persist(product);                       // same as JPA
Product p = session.get(Product.class, 42L);    // like find()
session.merge(product);
session.remove(product);

// Hibernate-only extras
session.setJdbcBatchSize(50);
List<Product> many = session.byMultipleIds(Product.class).multiLoad(1L, 2L, 3L);
Product bySku = session.bySimpleNaturalId(Product.class).load("SKU-BOAT-450"); // needs @NaturalId

Deprecated Methods You Will See in Old Code

Old Hibernate 5 method	Hibernate 6 replacement
`session.save(p)`	`session.persist(p)`
`session.update(p)`	`session.merge(p)`
`session.saveOrUpdate(p)`	`persist` for new, `merge` for existing
`session.delete(p)`	`session.remove(p)`
`session.load(Product.class, id)`	`session.getReference(Product.class, id)`
`session.createCriteria(...)`	JPA Criteria API (`CriteriaBuilder`)

Tip: In interviews, mention that save/update/saveOrUpdate were deprecated in Hibernate 6.0 in favour of the JPA methods.

Plain Hibernate Bootstrapping

SessionFactory sessionFactory = new Configuration()
        .configure()                         // reads hibernate.cfg.xml
        .addAnnotatedClass(Product.class)
        .buildSessionFactory();

sessionFactory.inTransaction(session -> {    // Hibernate 6: begins, commits or rolls back for you
    session.persist(new Product("SKU-USB-C", "USB-C Cable", new BigDecimal("199.00"), 500, "Accessories"));
});

Product p = sessionFactory.fromTransaction(session -> session.get(Product.class, 1L));

<!DOCTYPE hibernate-configuration PUBLIC
  "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
  "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.connection.url">jdbc:h2:mem:shopease</property>
    <property name="hibernate.connection.username">sa</property>
    <property name="hibernate.hbm2ddl.auto">create</property>
    <property name="hibernate.show_sql">true</property>
  </session-factory>
</hibernate-configuration>