How does the removal and release of resources occur for beans in the system?

In Java, especially in the context of the Spring Framework, the removal and release of resources from beans occur through lifecycle methods. When the Spring container destroys a bean (for example, when the application is shutting down or when a scope is removed), a method annotated with @PreDestroy or a method specified in the configuration as a destroy-method is called.

In this method, resources such as open database connections, streams, files, etc., are usually released. If the bean implements the DisposableBean interface, the destroy() method is called.

Example:

@Component
public class MyBean implements DisposableBean {

    @Override
    public void destroy() throws Exception {
        // release resources
        System.out.println("Resources released");
    }

    @PreDestroy
    public void cleanup() {
        // alternative way
        System.out.println("Cleanup before bean destruction");
    }
}

Thus, resource release occurs in methods that are called by the container upon bean destruction, ensuring proper shutdown and preventing memory or resource leaks.