Hibernate with Spring Boot

What Spring Boot Provides

Adding spring-boot-starter-data-jpa brings in Hibernate, Spring Data JPA, and transaction support. Spring Boot manages the Hibernate version. Spring Boot 3 uses Hibernate 6, and Spring Boot 4 uses Hibernate 7, so the project doesn't declare a Hibernate version.

Boot creates the EntityManagerFactory and the connection pool from the properties file. The hibernate.cfg.xml file is not needed.

spring.datasource.url=jdbc:postgresql://localhost:5432/appdb
spring.datasource.username=app
spring.datasource.password=secret
spring.jpa.hibernate.ddl-auto=validate
spring.jpa.show-sql=true

public interface StudentRepository extends JpaRepository<Student, Long> {
    List<Student> findByStatus(Status status);
}

@Service
public class StudentService {
    private final StudentRepository repository;

    public StudentService(StudentRepository repository) {
        this.repository = repository;
    }

    @Transactional
    public Student create(Student student) {
        return repository.save(student);
    }
}

Code Explanation:

• The datasource properties configure the connection, and Boot uses HikariCP by default.
• spring.jpa.hibernate.ddl-auto maps to hibernate.hbm2ddl.auto.
• JpaRepository provides CRUD methods, and findByStatus becomes a query based on its name.
• @Transactional opens a transaction around the method and commits or rolls back automatically.
• repository.save() belongs to Spring Data. It is not the removed Hibernate Session.save().

If the native Hibernate API is needed, inject an EntityManager and call unwrap(Session.class).