Event Bus 设计模式学习笔记

/**
 * interface describing a generic event, and it's associated meta data, it's this what's going to
 * get sent in the bus to be dispatched to intrested Subscribers
 */
public interface Event<T> {

  /**
   * @returns the stored data associated with the event
   */
  T getData();
}

import java.util.Set;

/**
 * Description of a generic subscriber
 */
public interface Subscribable {

  /**
   * Consume the events dispatched by the bus, events passed as parameter are can only be of type
   * declared by the supports() Set
   */
  void handle(Event<?> event);

  /**
   * describes the set of classes the subscribable object intends to handle
   */
  Set<Class<?>> supports();
}

import java.util.List;

/**
 * Description of the contract of a generic EventBus implementation, the library contains two main
 * version, Sync and Async event bus implementations, if you want to provide your own implementation
 * and stay compliant with the components of the library just implement this contract
 */
public interface EventBus {

  /**
   * registers a new subscribable to this EventBus instance
   */
  void register(Subscribable subscribable);

  /**
   * send the given event in this EventBus implementation to be consumed by interested subscribers
   */
  void dispatch(Event<?> event);

  /**
   * get the list of all the subscribers associated with this EventBus instance
   */
  List<Subscribable> getSubscribers();
}