Hibernate ORM 6 introduces several changes to its API compared to previous versions, especially in how SessionFactory and Session are used due to compliance with Jakarta EE and its updated imports (jakarta.persistence.*).
Here’s a simple guide to using SessionFactory and Session in Hibernate 6:

1. Add Hibernate Dependencies

Make sure to include the Hibernate 6 dependencies in your project. If you’re using Maven, the dependency would look like this:

<dependency>
    <groupId>org.hibernate.orm</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>6.4.4.Final</version>
</dependency>

2. Configure Hibernate

Use or Properties for configuration:hibernate.cfg.xml

Example: hibernate.cfg.xml

<hibernate-configuration>
    <session-factory>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/your_database</property>
        <property name="hibernate.connection.username">your_username</property>
        <property name="hibernate.connection.password">your_password</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">update</property>
    </session-factory>
</hibernate-configuration>

Alternatively, use Java configuration with Properties:

Properties properties = new Properties();
properties.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
properties.put("hibernate.connection.driver_class", "org.postgresql.Driver");
properties.put("hibernate.connection.url", "jdbc:postgresql://localhost:5432/your_database");
properties.put("hibernate.connection.username", "your_username");
properties.put("hibernate.connection.password", "your_password");
properties.put("hibernate.show_sql", "true");
properties.put("hibernate.hbm2ddl.auto", "update");

3. Create a SessionFactory

Starting with Hibernate 6, the SessionFactory should be built using the StandardServiceRegistryBuilder and MetadataSources.

Here’s an example:

Using hibernate.cfg.xml:

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;

public class HibernateUtil {

    private static SessionFactory sessionFactory;

    static {
        // Build the ServiceRegistry using hibernate.cfg.xml
        StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                .configure("hibernate.cfg.xml") // Loads hibernate.cfg.xml by default
                .build();

        try {
            // Build SessionFactory
            sessionFactory = new MetadataSources(registry).buildMetadata().buildSessionFactory();
        } catch (Exception e) {
            StandardServiceRegistryBuilder.destroy(registry);
            throw new ExceptionInInitializerError("SessionFactory build failed: " + e.getMessage());
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void shutdown() {
        getSessionFactory().close();
    }
}

Using Java configuration with Properties:

package org.kodejava.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;

import java.util.Properties;

public class HibernateUtil {

    private static SessionFactory sessionFactory;

    static {
        // Create Hibernate properties
        Properties properties = new Properties();
        properties.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
        properties.put("hibernate.connection.driver_class", "org.postgresql.Driver");
        properties.put("hibernate.connection.url", "jdbc:postgresql://localhost:5432/your_database");
        properties.put("hibernate.connection.username", "your_username");
        properties.put("hibernate.connection.password", "your_password");
        properties.put("hibernate.show_sql", "true");
        properties.put("hibernate.hbm2ddl.auto", "update");

        // Build the ServiceRegistry
        StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                .applySettings(properties)
                .build();

        try {
            // Build SessionFactory
            sessionFactory = new MetadataSources(registry).buildMetadata().buildSessionFactory();
        } catch (Exception e) {
            StandardServiceRegistryBuilder.destroy(registry);
            throw new ExceptionInInitializerError("SessionFactory build failed: " + e.getMessage());
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void shutdown() {
        getSessionFactory().close();
    }
}

4. Use SessionFactory to Get a Session

A Session represents a single unit of work with the database. In Hibernate 6, the usage involves a similar pattern to previous versions.

package org.kodejava.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

public class App {
    public static void main(String[] args) {
        SessionFactory sessionFactory = HibernateUtil.getSessionFactory();

        // Obtain a session
        try (Session session = sessionFactory.openSession()) {
            // Begin transaction
            session.beginTransaction();

            // Perform operations (e.g., save entities)
            MyEntity entity = new MyEntity();
            entity.setName("Example");
            session.persist(entity);

            // Commit the transaction
            session.getTransaction().commit();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // Shutdown the session factory
            HibernateUtil.shutdown();
        }
    }
}

5. Entity Example

Ensure your entity classes are annotated correctly with Jakarta Persistence annotations (jakarta.persistence.*).

package org.kodejava.hibernate;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;

@Entity
public class MyEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    // Getters and Setters
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

Key Updates in Hibernate 6

1. Jakarta Imports: Hibernate moved from javax.persistence.* to jakarta.persistence.*.
2. Default Configuration: The APIs are adaptive, but the configuration process is largely unchanged.
3. Session Persistence: The Session.persist(Object) method is preferred over deprecated methods like save(Object).

By following these steps, you can effectively use SessionFactory and Session in Hibernate 6 for your application.