Bean and DTO are terms of classes used in Spring Boot. But they are different from each other like purposes and usages within the Spring Boot application. This topic will help use to explore the difference between Bean and DTO, their annotations, how they’re used in real-world applications, and when to choose one over the other.
Bean in Spring Boot
A Spring Bean class’s object is managed by the Spring container.
Example:
@Service
public class EmailService {
public void sendEmail(String to, String body) {
System.out.println("Email sent to " + to);
}
}DTO
This is a class. It is using for sending or receiving data.
Example:
public class UserDTO {
private String name;
private String email;
public UserDTO() {}
public UserDTO(String name, String email) {
this.name = name;
this.email = email;
}
// Getters and Setters
}Key Difference Between Bean and DTO
| Feature | Spring Bean | DTO |
| Purpose | Handles logic, service, or configuration | Transfers data across layers or systems |
| Managed by Spring | Yes | No |
| Annotations | Use annotations such as @Component, @Service, etc. | None |
| Includes Business Logic? | Yes | No |
| Used In | Service layer, config classes, data access | API request/response, inter-layer communication |
| Dependency Injection? | Yes (@Autowired) | No (manually instantiated or mapped) |
| Framework Dependency | Spring Framework | Framework-agnostic |
When to Use Bean vs DTO
Use Bean When
- We are creating a service, repository, or config component.
- We want Spring to inject it into other components.
- We need logic execution or task handling.
Use DTO When
- We are defining a REST API request or response format.
- We need to transfer structured data between layers.
- We want to filter or reshape data from entities or beans.
Real-World Example in a Spring Boot App
DTO:
public class ProductDTO {
private String name;
private double price;
// Constructors, Getters, Setters
}Bean:
@Service
public class ProductService {
public double applyDiscount(double price) {
return price * 0.9;
}
}Controller using both:
@RestController
@RequestMapping("/products")
public class ProductController {
@Autowired
private ProductService productService;
@PostMapping("/discount")
public double calculateDiscount(@RequestBody ProductDTO productDTO) {
return productService.applyDiscount(productDTO.getPrice());
}
}Conclusion
In Spring Boot:
- A Bean is a Spring-managed object responsible for executing logic, providing services, or managing configuration.
- A DTO is a data carrier, used to structure and transfer data across layers or APIs.