再谈领域事件

/**
 * 领域事件
 * Created by jiangwenkang on 16-11-17.
 */
public interface DomainEvent extends Serializable {
    Date occurredTime();
}

/**
 * 领域事件发布器
 * Created by jiangwenkang on 16-11-17.
 */
public class DomainEventPublisher {
    private static ConcurrentHashMap<Class<? extends DomainEvent>, List<DomainEventSubscriber<? extends DomainEvent>>> subscriberMap
            = new ConcurrentHashMap<>();

    public synchronized static <T extends DomainEvent> void subscribe(Class<T> domainEventClazz, DomainEventSubscriber<T> subscriber) {
        List<DomainEventSubscriber<? extends DomainEvent>> domainEventSubscribers = subscriberMap.get(domainEventClazz);
        if (domainEventSubscribers == null) {
            domainEventSubscribers = Lists.newArrayList();
        }
        domainEventSubscribers.add(subscriber);
        subscriberMap.put(domainEventClazz, domainEventSubscribers);
    }

    @SuppressWarnings("unchecked")
    public static <T extends DomainEvent> void publish(final T domainEvent) {
        if (domainEvent == null) {
            throw new IllegalArgumentException("domain event is null");
        }
        List<DomainEventSubscriber<? extends DomainEvent>> subscribers = subscriberMap.get(domainEvent.getClass());
        if (subscribers != null && !subscribers.isEmpty()) {
            for (DomainEventSubscriber subscriber : subscribers) {
                subscriber.handle(domainEvent);
            }
        }
    }
}

/**
 * 领域事件订阅器
 * Created by jiangwenkang on 16-11-17.
 */
public interface DomainEventSubscriber<T extends DomainEvent> {

    /**
     * 订阅者处理事件
     *
     * @param event 领域事件
     */
    void handle(T event);
}