11 Must‑Know Spring Extension Points to Supercharge Your Java Backend

11. Custom Scope

Define a custom scope by implementing Scope (e.g., thread‑local scope) and register it via a BeanFactoryPostProcessor.

public class ThreadLocalScope implements Scope {
    private static final ThreadLocal<Object> THREAD_LOCAL_SCOPE = new ThreadLocal<>();
    @Override
    public Object get(String name, ObjectFactory<?> objectFactory) {
        Object value = THREAD_LOCAL_SCOPE.get();
        if (value != null) {
            return value;
        }
        Object object = objectFactory.getObject();
        THREAD_LOCAL_SCOPE.set(object);
        return object;
    }
    @Override
    public Object remove(String name) {
        THREAD_LOCAL_SCOPE.remove();
        return null;
    }
    @Override
    public void registerDestructionCallback(String name, Runnable callback) {}
    @Override
    public Object resolveContextualObject(String key) { return null; }
    @Override
    public String getConversationId() { return null; }
}

@Component
public class ThreadLocalBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        beanFactory.registerScope("threadLocalScope", new ThreadLocalScope());
    }
}

@Scope("threadLocalScope")
@Service
public class CService {
    public void add() {}
}