Database Integrations in Spring Boot

Here are minimal examples of different Database Integrations in Spring Boot that you could choose from in your applications.

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1. JdbcTemplate (Plain JDBC)

JdbcTemplate is a lower-level approach that directly executes SQL queries.

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

@Repository
public class UserJdbcRepository {

    private final JdbcTemplate jdbcTemplate;

    public UserJdbcRepository(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    public List<User> findAll() {
        return jdbcTemplate.query("SELECT id, name FROM users", new RowMapper<User>() {
            @Override
            public User mapRow(ResultSet rs, int rowNum) throws SQLException {
                return new User(rs.getLong("id"), rs.getString("name"));
            }
        });
    }
}

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2. JPA with EntityManager

JPA with EntityManager is a standard way to work with entities in a more flexible manner.

import jakarta.persistence.EntityManager;
import jakarta.persistence.PersistenceContext;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public class UserJpaRepository {

    @PersistenceContext
    private EntityManager entityManager;

    public List<User> findAll() {
        return entityManager.createQuery("SELECT u FROM User u", User.class).getResultList();
    }
}

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3. Hibernate with SessionFactory

Hibernate SessionFactory provides more control over transactions and caching.

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public class UserHibernateRepository {


    @PersistenceContext
    private EntityManager entityManager;

    private Session getSession() {
        Session session = null;
        if (entityManager == null
            || (session = entityManager.unwrap(Session.class)) == null) {

            throw new NullPointerException();
        }
        return session;
    }

    public List<User> findAll() {
        return getSession().createQuery("from Platform", Platform.class).list();
    }
}

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4. Spring Data JPA Repository (Recommended)

This is the easiest and most common approach, using Spring’s CrudRepository or JpaRepository.

Implementation:

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
}

Usage:

import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/users")
public class UserController {

    private final UserRepository userRepository;

    public UserController(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @GetMapping
    public List<User> getUsers() {
        return userRepository.findAll();
    }
}

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Summary:

Approach	Pros	Cons
JdbcTemplate	Fine-grained control, better performance	More boilerplate code
JPA (EntityManager)	Standard API, more flexibility	Requires configuration
Hibernate Sessions	Powerful ORM features, caching	Requires managing sessions manually
Spring Data JPA	Easiest to use, built-in methods	Less fine-grained control

For most applications, Spring Data JPA (Repositories) is the best choice due to its simplicity. I use it primarily in my Spring Boot Apps