Getting Started with Spring Boot 3: A Beginner’s Guide

If you’re new to backend development with Java, or looking to modernize your stack, Spring Boot 3 is the best place to start. It combines the power of the Spring Framework with simplified configuration, embedded servers, and production-ready tools — all optimized for Java 17+.

In this guide, you’ll learn how to get started with Spring Boot 3, build your first API, and understand the project structure step by step. Whether you’re launching a new project or transitioning from an older Spring version, this is your one-stop beginner’s guide.

🧠 What is Spring Boot?

Spring Boot is a framework built on top of the Spring ecosystem. It reduces boilerplate code and simplifies the configuration of Spring-based applications.

🔑 Key Features:

Embedded Tomcat/Jetty server — no WAR deployment needed
Auto-configuration based on dependencies
Starter dependencies for rapid development
Health checks, metrics, and externalized configuration
Built-in support for REST APIs, security, data access, and more

⚙️ Prerequisites

Before starting, make sure you have:

Java 17 or higher installed
A Java IDE like IntelliJ IDEA, VS Code, or Spring Tool Suite
Maven or Gradle for dependency management
Internet access to download dependencies

🚀 Step 1: Create Your Project with Spring Initializr

Head over to start.spring.io and configure your project:

Project: Maven or Gradle
Language: Java
Spring Boot version: 3.x
Group: com.example
Artifact: demo
Dependencies:
- Spring Web
- Spring Boot DevTools

Click Generate, unzip the downloaded file, and open it in your IDE.

📁 Step 2: Explore the Project Structure

Your generated project will look like this:

src/
├── main/
│   ├── java/
│   │   └── com/example/demo/
│   │       ├── DemoApplication.java
│   │       └── controller/
│   └── resources/
│       ├── application.properties
│       └── static/
└── test/

Key files:

DemoApplication.java — main entry point
application.properties — configuration file
controller/ — where we’ll create our REST API

🛠️ Step 3: Create a Simple REST Controller

Create a new file HelloController.java inside com.example.demo.controller:

package com.example.demo.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @GetMapping("/api/hello")
    public String sayHello() {
        return "Hello from Spring Boot 3!";
    }
}

▶️ Step 4: Run the Application

In your IDE, run the DemoApplication.java class, or use the terminal:

./mvnw spring-boot:run

Now visit: http://localhost:8080/api/hello

You should see:

Hello from Spring Boot 3!

⚙️ Step 5: Customize Configuration

Edit src/main/resources/application.properties:

server.port=8081
spring.application.name=demo-app

You’ve just changed the port and given your app a custom name.

🧱 Optional: Add a Service Layer

Let’s refactor with a service for better separation of concerns:

HelloService.java

package com.example.demo.service;

import org.springframework.stereotype.Service;

@Service
public class HelloService {
    public String getGreeting() {
        return "Hello from the service layer!";
    }
}

HelloController.java

@Autowired
private HelloService helloService;

@GetMapping("/api/service-hello")
public String getHelloFromService() {
    return helloService.getGreeting();
}

This structure scales better for real-world applications.

🔎 Spring Boot 3 Highlights

Spring Boot 3 introduced several modern enhancements:

✅ Requires Java 17+
✅ Supports GraalVM native images for faster startup
✅ Improved AOT (Ahead-of-Time) compilation
✅ Better Observability & Micrometer support
✅ Cleaned up deprecated APIs and more modular structure

🧠 Final Thoughts

Spring Boot 3 is an excellent starting point for building modern, secure, and scalable Java applications. With built-in support for REST APIs, auto-configuration, and easy project setup, it drastically simplifies backend development — whether you’re building a microservice or a full SaaS platform.

Now that your basic app is working, consider adding:

✅ CRUD endpoints with Spring Data JPA
✅ Authentication with Spring Security
✅ Integration with PostgreSQL or MySQL
✅ Unit and integration tests
✅ Docker support for deployment