Chapter 11: Understanding @SpringBootApplication Annotation | Spring Boot Course

Ramesh Fadatare

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Apr 23, 2025

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In this chapter, we will learn everything about the @SpringBootApplication Annotation with examples.

If you’ve ever started a Spring Boot project, you’ve probably seen this line at the top of your main class:

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

But what does @SpringBootApplication actually do? And why is it important?

Let’s break it down in simple terms.

What Is @SpringBootApplication?

@SpringBootApplication is a special annotation that tells Spring Boot to:

• Set up the basic configuration
• Scan for components (like @Controller, @Service, etc.)
• Enable auto-configuration so your app is ready to run

In short: It bootstraps your entire Spring Boot app.

What Is It Made Of?

@SpringBootApplication is actually a combination of three annotations:

@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan

Let’s understand each one.

1. @SpringBootConfiguration

This is a specialized form of @Configuration, which tells Spring:

“This class contains bean definitions.”

It allows you to define beans using @Bean methods if needed.

2. @EnableAutoConfiguration

This is the magic that makes Spring Boot awesome!

It tells Spring Boot:

“Try to guess and configure things based on what’s on the classpath.”

For example:

• If you have spring-boot-starter-web, it configures Spring MVC and an embedded Tomcat server.
• If you add Spring Data JPA, it configures Hibernate and…