Intro to Spring Boot

Spring Framework is massive. It handles dependency injection, security, database access, and more. But it was hard to set up.

Spring Boot makes it easy. It is an opinionated framework that allows you to create stand-alone, production-grade Spring based Applications that you can "just run".

Why Spring Boot?

• Auto Configuration: It automatically configures Spring based on the jar dependencies you added.
• Standalone: It creates stand-alone applications that run on their own embedded web server (Tomcat, Jetty). No need to deploy WAR files!
• Opinionated: It provides "starter" dependencies to simplify build configuration.

Dependency Injection (IoC)

At the heart is the Inversion of Control (IoC) container. instead of creating objects (new Service()), you ask Spring to give you an instance.

@Service
public class UserService { ... }

@RestController
public class UserController {
    @Autowired // Spring injects the service here automatically
    private UserService userService;
}

Annotations

Spring relies heavily on annotations.

• @SpringBootApplication: Main entry point.
• @Component: A generic Spring managed component.
• @Service: Business logic.
• @Repository: Database access.
• @Controller: Web Request handling.

Interactive Code

Simulate Dependency Injection concept!

Quiz

Next Steps

Let's build something real. An API.