How to Build a Simple REST API with Spring Boot: A Step-by-Step Guide

Spring Boot is a java framework , that makes developers life easy by simplifying the process of creating and running java application especially web applications. It provides preconfigured dependencies , auto configuration and other features that reduces complexity and time to develop the application.

Today we will learn to build a simple REST API with spring boot and will test it. So let’s get started without further ado.

Step 0: Create a Spring Boot project using Spring Initializr.

To start building a Spring Boot project, go to Spring Initializr, select Maven as the project type, and use Spring Boot version 3.4.5. Set the project metadata with the group as com.example, artifact as myfirstproject, and other details. Add dependencies like Spring Web and optionally Lombok. Download the project as a Zip file, unzip it, and import it into your Java IDE as a Maven project. Wait for the IDE to set up the project, and you're ready to begin.

Step 1: Create a Model class.

public class Book {
    private Long id;
    private String title;
    private String author;

    //Create Constructors and Getter and Setter (If you didnt add Lombok dependency)

    // Constructors
    public Book() {}
    public Book(Long id, String title, String author) {
        this.id = id;
        this.title = title;
        this.author = author;
    }

    // Getters and setters
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getTitle() { return title; }
    public void setTitle(String title) { this.title = title; }
    public String getAuthor() { return author; }
    public void setAuthor(String author) { this.author = author; }
}

Step 2 : Create Rest Controller

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

@RestController
@RequestMapping("/books")
public class BookController {

    private List<Book> books = new ArrayList<>();

    @GetMapping
    public List<Book> getAllBooks() {
        return books;
    }

    @PostMapping
    public Book addBook(@RequestBody Book book) {
        books.add(book);
        return book;
    }
}

Step 3: Run Your Application
Run the main class annotated with @SpringBootApplication. Your application will start at port http://localhost:8080.

Step 4: Use Postman to test your applocation.
Get All Books : GET http://localhost:8080/books
Add a new book : POST http://localhost:8080/books

Body (JSON):

{
  "id": 1,
  "title": "Clean Code",
  "author": "Robert C. Martin"
}

Conclusion:

You just created a basic REST API using Spring Boot! Next, you can extend this by adding database support, validation, or security.

Hope this article help you to create your first spring boot application .
Thank You. See you next time . Happy Learning !!!