How to Create a REST API using Java Spring Boot

Creating a REST API using Spring Boot allows developers to build scalable and production-ready web services with minimal configuration. It simplifies RESTful service development by providing built-in support for HTTP methods, dependency injection, and auto-configuration.

• Offers embedded servers (Tomcat/Jetty) to run applications without external deployment
• Supports API testing using tools like Postman or Swagger UI
• Allows easy configuration via application.properties or application.yml

Why Spring Boot?

Spring Boot makes it easy to create production-ready apps:

• Built on top of Spring Framework
• Reduces boilerplate code with auto-configurations
• Quick setup for REST APIs
• Beginner-friendly

Steps to Implements a REST API in Spring Boot

Follow the below steps to create and run a REST API in Spring Boot.

Step 1: Create the Spring Boot Project

Using Spring Initializr (Recommended)

1. Open Spring Initializr in your browser.
2. Fill in the project details:

• Project: Maven
• Language: Java
• Spring Boot version: (latest stable, e.g., 3.1.x)
• Group: com. example
• Artifact: demo
• Name: demo
• Packaging: Jar
• Java version: 17+

3. Click Add Dependencies-> Select Spring Web.
4. Click Generate-> It will download a .zip file.
5. Extract the zip-> Open it in your IDE (IntelliJ / Eclipse / VS Code).

Step 2: Define the Employee Entity

Create a simple Employee class inside com.example.demo:

Step 3: Create a Storage Class

Create a class to hold a list of employees.

Step 4: Create the DAO Class

The DAO class will handle adding and retrieving employees.

Step 5: Create the Controller

The controller contains the REST API endpoints.

Step 6: Run the Application

Open DemoApplication.java (already generated by Spring Boot) and run it:

Step 7: Testing the API

Now we can test the API using tools like Postman or a web browser.

GET Request: Fetch all employees

URL: http://localhost:8080/employees/

Response:

POST Request: Add a new employee

Response:

Again hitting the GET request after performing the POST request:

This concludes creating a REST API using Spring Boot. Now we have a fully functioning API to manage employees.