Spring Bean Creation & Lifecycle

The Lifecycle of a Spring Bean

Every Spring Bean passes through well-defined stages:

1. 1. Instantiation: Spring runs new MyBean() behind the scenes.
2. 2. Populate Properties: Spring injects all dependencies into the constructor or fields.
3. 3. Post-Construct (@PostConstruct): Spring executes your custom initialization method.
4. 4. Bean Ready: The bean is active and serving requests in your application.
5. 5. Pre-Destroy (@PreDestroy): When app shuts down, Spring calls clean-up methods (close DB connections, release files).

@Component
public class DatabaseConnectionBean {

    @PostConstruct
    public void init() {
        System.out.println("Step 3: Bean initialized! Connecting to DB...");
    }

    @PreDestroy
    public void cleanup() {
        System.out.println("Step 5: App stopping! Closing DB connections gracefully...");
    }
}