Integrating H2 Database with Spring Data JPA

October 13, 2025

#1

This guide shows how to integrate H2 database with Spring Data JPA in a Spring Boot project for quick development and testing.

1. Add Dependencies

In pom.xml:

<dependency>
  <groupId>com.h2database</groupId>
  <artifactId>h2</artifactId>
  <scope>runtime</scope>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

2. Configure H2

In application.properties:

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=update
spring.h2.console.enabled=true
spring.h2.console.path=/h2-console

3. Create Entity

import jakarta.persistence.*;

@Entity
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String role;
}

4. Repository

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

public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}

5. Service Layer (Optional)

import org.springframework.stereotype.Service;
import java.util.List;

@Service
public class EmployeeService {
    private final EmployeeRepository repo;

    public EmployeeService(EmployeeRepository repo) {
        this.repo = repo;
    }

    public List<Employee> getAll() {
        return repo.findAll();
    }

    public Employee save(Employee e) {
        return repo.save(e);
    }
}

6. Controller

import org.springframework.web.bind.annotation.*;
import java.util.List;

@RestController
@RequestMapping("/employees")
public class EmployeeController {
    private final EmployeeService service;

    public EmployeeController(EmployeeService service) {
        this.service = service;
    }

    @GetMapping
    public List<Employee> all() {
        return service.getAll();
    }

    @PostMapping
    public Employee add(@RequestBody Employee e) {
        return service.save(e);
    }
}

7. Run and Test

Start the app:

mvn spring-boot:run

• Visit /h2-console to inspect data.
• JDBC URL: jdbc:h2:mem:testdb.
• Use REST endpoints to add and fetch employees.