Understanding Spring Boot MVC

In the previous blog, we got an overview of a Basic Spring Boot Application. Now, let's dive deeper and understand how the core components work together in an MVC structure.

Before Starting, We Should Know:

1. Model

The Model represents the data and business logic of the application. It defines the structure of the data we are working with.

Example:

public class User {
    private Long id;
    private String name;
    private String email;

    // Getters and Setters
}

2. Repository

The Repository layer interacts with the database. It is responsible for data storage, retrieval, and query execution.

Example:

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

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

3. Service

The Service layer contains business logic. It processes data before sending it to the Controller.

Example:

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

@Service
public class UserService {
    private final UserRepository userRepository;

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

    public List<User> getAllUsers() {
        return userRepository.findAll();
    }
}

4. Controller

The Controller handles user requests, interacts with the Service layer, and returns responses.

Example:

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

@RestController
@RequestMapping("/users")
public class UserController {
    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping
    public List<User> getUsers() {
        return userService.getAllUsers();
    }
}

5. Exception Handling

Exception handling is important to manage errors gracefully. Spring Boot provides @ControllerAdvice for centralized exception handling.

Example:

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

@RestControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(Exception.class)
    public String handleException(Exception e) {
        return "Error: " + e.getMessage();
    }
}

How Everything Works Together

1. The Controller receives a request (e.g., /users).
2. It calls the Service layer to process data.
3. The Service interacts with the Repository to fetch or save data.
4. The Repository retrieves data from the database.
5. The Service returns the data to the Controller.
6. The Controller sends a response to the client.
7. If an error occurs, the Exception Handling mechanism takes care of it.

This is how Spring Boot MVC works in a structured way!

In the upcoming Blog, we will learn about Annotations in Spring Boot.
Keep learning, keep growing! 🚀