Spring Boot Project Structure🌱 Beginner

A freshly generated Spring Boot project follows a highly predictable, standardized layout. This uniformity means an experienced Spring developer can jump into any project and instantly know where things belong.

What is the Layout?

Spring Boot projects are divided into src/main/java for logic and src/main/resources for configuration and static assets.

my-app/
├─ src/main/java/com/example/demo/
│  ├─ DemoApplication.java     # The application entry point
│  ├─ controller/              # The web layer (handles HTTP requests)
│  ├─ service/                 # The business logic layer
│  └─ repository/              # The database access layer
├─ src/main/resources/
│  ├─ application.properties   # Core configuration settings
│  └─ static/ , templates/     # Static files and server-rendered views
├─ src/test/java/...           # Unit and integration tests
├─ pom.xml                     # Maven build configuration
└─ mvnw                        # The Maven wrapper script

How the Entry Point Works

Every Spring Boot application starts from a class annotated with @SpringBootApplication. This class contains a standard Java main method that delegates to SpringApplication.run().

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

Why is @SpringBootApplication Important?

This single annotation is a powerful shortcut that actually bundles three crucial configurations together:

• @Configuration: Flags the class as a source of bean definitions.
• @EnableAutoConfiguration: Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings.
• @ComponentScan: Instructs Spring to look for other components, configurations, and services in the current package, allowing it to find the controllers.