📦 Spring Boot IoC Container

🧠 What is IoC Container?

The IoC (Inversion of Control) Container is the core part of Spring that:

• ✅ Creates your objects (beans)
• ✅ Manages them
• ✅ Injects their dependencies
• ✅ Controls their lifecycle

You don’t manually create or connect objects — Spring does it for you.

🔁 Inversion of Control?

Normal (manual) object creation:

MyService service = new MyService();

Spring Boot style (IoC-managed):

@Component
public class MyService { }

@Autowired
MyService service;  // Spring injects this

This is Inversion of Control — you give up control to the container.

📦 In Spring Boot

Spring Boot automatically starts the IoC container when your application runs:

@SpringBootApplication
public class MyApp {
    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args); // starts IoC container
    }
}

Under the hood, this creates an ApplicationContext, which is the Spring IoC container.

✅ What IoC Container Does

Task	Example
Finds beans	@Component, @Service, etc.
Creates beans	Using constructors
Injects dependencies	@Autowired, constructor injection
Manages lifecycle	@PostConstruct, @PreDestroy

📌 One Line Summary

The IoC Container in Spring Boot is the system that automatically finds, creates, connects, and manages your objects (beans).

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