Creating Your First REST API with Spring Boot

 Spring Boot makes it incredibly easy to create RESTful web services with minimal setup. As a Java developer, building your first REST API using Spring Boot can be a great way to understand the power and simplicity of the framework. In this blog, we’ll walk through the steps to build a basic REST API that performs simple operations like retrieving and adding data.

What is a REST API?

REST (Representational State Transfer) is an architectural style used for designing web services that communicate over HTTP. A REST API allows clients to interact with the server using standard HTTP methods like GET, POST, PUT, and DELETE.

Step 1: Set Up the Project

Use Spring Initializr to generate a new Spring Boot project:

Project Type: Maven

Language: Java

Dependencies: Spring Web

Download and unzip the project, then open it in your IDE (e.g., IntelliJ IDEA or Eclipse).

Step 2: Create a Model Class

Create a simple User class to represent data.

public class User {

    private Long id;

    private String name;

    // Constructors, getters, and setters

}

Step 3: Create a REST Controller

Create a controller class to handle API requests.

@RestController

@RequestMapping("/api/users")

public class UserController {

    private List<User> users = new ArrayList<>();

    @GetMapping

    public List<User> getAllUsers() {

        return users;

    }

    @PostMapping

    public User addUser(@RequestBody User user) {

        users.add(user);

        return user;

    }

}

@RestController makes the class a REST controller.

@RequestMapping defines the base URL.

@GetMapping and @PostMapping handle HTTP GET and POST requests respectively.

@RequestBody maps incoming JSON to a Java object.

Step 4: Run the Application

Run the application using:

./mvnw spring-boot:run

Or simply run the main method in the Application class. Once the server starts, you can access your API:

GET http://localhost:8080/api/users – Retrieves all users

POST http://localhost:8080/api/users – Adds a new user (with JSON body)

Step 5: Test Your API

Use tools like Postman or cURL to test your endpoints. Send a JSON body like:


{

  "id": 1,

  "name": "Alice"

}

Conclusion

Spring Boot simplifies REST API development by handling configuration and boilerplate code for you. With just a few lines of code, you can build and run a working API. As you grow more comfortable, you can add features like validation, database integration, and exception handling to make your APIs production-ready.

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