How does Spring Boot Application achieve auto configuration internally, explain the use of @EnableAutoConfiguration?

Spring Boot's auto-configuration feature is one of its key strengths, enabling developers to rapidly build and deploy applications with minimal configuration. Let me explain how it achieves this and the role of @EnableAutoConfiguration:

Internally, Spring Boot auto-configuration works by scanning the classpath for specific libraries and dependencies commonly used in Spring applications. It then automatically configures beans and components based on the presence of these libraries and the current environment.

The @EnableAutoConfiguration annotation plays a central role in this process. When we include this annotation in our application, Spring Boot automatically configures the beans required to set up a functional application context.

Here's an example to illustrate how @EnableAutoConfiguration works:

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

In this example, we have a Spring Boot application class annotated with @SpringBootApplication and @EnableAutoConfiguration. When the application starts, Spring Boot scans the classpath and automatically configures beans for common components like data sources, JPA, security, etc., based on the libraries detected in the classpath.

For instance, if Spring Boot detects Hibernate on the classpath, it automatically configures a DataSource, EntityManagerFactory, and TransactionManager for JPA persistence. Similarly, if Spring Security is present, it configures security-related beans like AuthenticationManager and FilterChainProxy.

By leveraging @EnableAutoConfiguration, Spring Boot simplifies application setup and eliminates the need for manual configuration, allowing developers to focus more on writing business logic rather than boilerplate configuration.