How does Spring Boot load its modules and components?

Spring Boot uses an auto-configuration mechanism based on annotations and conditional checks to automatically load and configure necessary modules and components. When starting a Spring Boot application, it scans the classpath, looks for classes with annotations such as @Configuration, @Component, @Service, and @Repository, and creates corresponding beans in the application context.

A key role is played by the @EnableAutoConfiguration annotation, which activates auto-configuration using spring.factories files, where configuration classes for various modules are listed. These configurations are conditionally applied, for example, if a certain library is present in the classpath or if custom configuration is absent.

Example:

@SpringBootApplication // includes @EnableAutoConfiguration, @ComponentScan, and @Configuration
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Thus, Spring Boot automatically loads and configures components, minimizing the need for manual configuration.