How is data integrity ensured when using transactions in Spring together with Hibernate?

In Spring, together with Hibernate, data integrity when using transactions is ensured through transaction management at the Spring level and Hibernate's transaction mechanism.

Spring provides an abstraction of transactions via PlatformTransactionManager, which allows starting, committing, or rolling back a transaction. Hibernate, in turn, works with database transactions through a session (Session).

When a method is annotated with @Transactional, Spring automatically opens a transaction before executing the method and commits it after successful completion. If an exception occurs during execution, the transaction is rolled back, preventing partial data saving and maintaining integrity.

Example:

@Service
public class UserService {

    @Transactional
    public void createUser(User user) {
        entityManager.persist(user);
        // If an exception occurs here, the transaction will be rolled back
    }
}

Thus, transactions guarantee that all operations within the method are either fully executed or not applied at all, ensuring data consistency.