Building Your First Spring Boot App: A Complete Guide to MVC Architecture and REST Controllers

Learn how to build your first Spring Boot application using the MVC architecture and REST controllers. This guide covers the essential Spring concepts such as Inversion of Control (IoC), Dependency Injection, and annotations like @RestController and @SpringBootApplication. Whether you're a beginner or an experienced developer, this guide will help you build scalable applications with Spring Boot. Watch our detailed session on YouTube TechEazy Consulting and sign up for the full course at TechEazy Consulting to start mastering Spring Boot today.

Building your first Spring Boot application is an exciting step in mastering Java development. In this blog, we will guide you through the core concepts of Spring Boot, including how to build your first application using MVC architecture, REST controllers, and basic CRUD operations. By the end of this guide, you will have a working Spring Boot application ready to deploy.

Key Topics Covered

1. Revisiting Core Spring Concepts

Before jumping into the code, it’s essential to revise some of the foundational Spring concepts:

• Inversion of Control (IoC): Shifting the control of object creation to the Spring framework.

• Dependency Injection (DI): Injecting required dependencies into classes automatically using @Autowired.

• Spring Annotations: Understanding key Spring Boot annotations such as @SpringBootApplication, @RestController, @Service, and @Repository.

These concepts help you build clean, maintainable, and scalable applications.

2. Building Your First Spring Boot Application

Creating a Spring Boot project is simple. Using Spring Initializr at start.spring.io, you can generate a new Spring Boot project with the necessary dependencies such as Spring Web and Spring Data JPA.

Sample Code:

@SpringBootApplication
public class FirstApp {
    public static void main(String[] args) {
        SpringApplication.run(FirstApp.class, args);
    }
}

@RestController
@RequestMapping("/api/orders")
public class OrderController {

    @GetMapping("/{id}")
    public ResponseEntity<Order> getOrder(@PathVariable Long id) {
        Order order = orderService.findById(id);
        return new ResponseEntity<>(order, HttpStatus.OK);
    }

    @PostMapping
    public ResponseEntity<String> createOrder(@RequestBody Order order) {
        orderService.save(order);
        return new ResponseEntity<>("Order created successfully!", HttpStatus.CREATED);
    }
}

In this example, we use @SpringBootApplication to configure the application and @RestController to handle HTTP requests for orders. You can define CRUD operations using Spring Data JPA and manage requests through the controller.

3. MVC Architecture in Spring Boot

Spring Boot follows the Model-View-Controller (MVC) design pattern. The layers are as follows:

• Model: Represents the data and business logic of the application (e.g., Order class).

• View: The user interface layer.

• Controller: Handles HTTP requests and communicates between the View and Model layers.

Spring’s MVC architecture ensures a clear separation of concerns, making applications easier to maintain and scale.

4. REST Controllers in Spring Boot

Spring Boot allows you to easily create RESTful web services with @RestController. These controllers expose APIs to the frontend, mobile applications, or other services.

Key Features:

• @GetMapping, @PostMapping, @PutMapping, @DeleteMapping: Map HTTP methods to specific operations.

• @RequestBody: Bind request data to method parameters for POST/PUT requests.

• @PathVariable: Extract variables from the URL for dynamic endpoints.

5. Use Case: Last Mile Delivery System

A practical example discussed in this session is a Last Mile Delivery System. This system allows clients to upload order details, track parcels, manage users, and generate reports.

Key Components:

• Entities: Client, Order, Parcel, Message, Report.

• CRUD Operations: Create, Read, Update, Delete resources for entities.

• Security: Role-based access control (RBAC) for different users such as clients, supervisors, and admins.

By implementing this use case, you will get hands-on experience with building full-stack applications using Spring Boot.

Next Steps

Spring Boot simplifies building Java applications by providing robust tools and architecture to create scalable applications. To dive deeper, watch our full video tutorial on our YouTube channel TechEazy Consulting, and for a comprehensive learning experience, register for our full course at TechEazy Consulting.