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Spring Boot
Spring Boot with JPA & Hibernate

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Spring Boot provides seamless integration with JPA (Java Persistence API) and Hibernate for handling database operations.

What is JPA & Hibernate?

  • JPA (Java Persistence API): A specification for object-relational mapping (ORM) in Java.
  • Hibernate: A popular JPA implementation used to interact with relational databases.

Spring Boot uses Spring Data JPA, which simplifies database interactions with less boilerplate code.

Setting Up Spring Boot with JPA & Hibernate

Step 1: Add Dependencies (pom.xml)

<dependencies>
<!-- Spring Boot Starter JPA -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<!-- MySQL Driver -->
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<version>9.1.0</version>
</dependency>

<!-- Spring Boot Starter Web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>

</dependencies>

Step 2: Configure application.properties

# ✅ Database Configuration
spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=

# ✅ Hibernate Configuration
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.database-platform=org.hibernate.dialect.MySQL8Dialect

✅ spring.jpa.hibernate.ddl-auto=update

  • create: Creates tables every time (deletes old data).
  • update: Updates schema (recommended).
  • none: No automatic changes.

Step 3: Create Entity Class (User.java)

import jakarta.persistence.*;

@Entity
@Table(name = "users") // Table name in MySQL
public class User {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY) // Auto-increment ID
private Long id;

@Column(nullable = false)
private String name;

@Column(unique = true, nullable = false)
private String email;

// Constructors
public User() {}

public User(String name, String email) {
this.name = name;
this.email = email;
}

// Getters & 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; }

public String getEmail() { return email; }
public void setEmail(String email) { this.email = email; }
}

Step 4: Create Repository (UserRepository.java)

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

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
// Custom queries can be added here
}

✅ Spring Data JPA automatically provides CRUD operations!

  • findAll(), findById(id), save(entity), deleteById(id).

Step 5: Create Service Layer (UserService.java)

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.Optional;

@Service
public class UserService {

@Autowired
private UserRepository userRepository;

// Get all users
public List<User> getAllUsers() {
return userRepository.findAll();
}

// Get user by ID
public Optional<User> getUserById(Long id) {
return userRepository.findById(id);
}

// Save user
public User saveUser(User user) {
return userRepository.save(user);
}

// Update user
public void updateUser(User user) {
userRepository.save(user);
}

// Delete user
public void deleteUser(Long id) {
userRepository.deleteById(id);
}
}

Step 6: Create REST Controller (UserController.java)

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Optional;

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

@Autowired
private UserService userService;

// ✅ Get all users
@GetMapping
public List<User> getAllUsers() {
return userService.getAllUsers();
}

// ✅ Get user by ID
@GetMapping("/{id}")
public Optional<User> getUserById(@PathVariable Long id) {
return userService.getUserById(id);
}

// ✅ Create user
@PostMapping
public User createUser(@RequestBody User user) {
return userService.saveUser(user);
}

// ✅ Update user
@PutMapping("/{id}")
public String updateUser(@RequestBody User user) {
userService.updateUser(user);
return "User updated with ID: " + user.getId();
}

// ✅ Delete user
@DeleteMapping("/{id}")
public String deleteUser(@PathVariable Long id) {
userService.deleteUser(id);
return "User deleted with ID: " + id;
}
}

Running the Spring Boot Application

Run the application using your IDE or with the following Maven command:

mvn spring-boot:run

Spring Boot starts an embedded Tomcat server (default: http://localhost:8080).

Testing the REST API with Postman:

Once the application is running, test the endpoints:


Get All Users

Create a New User

Get a Single User by ID

Update a User

Delete a User


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