Simple Event-Driven System for Android

Inspired by the event-driven architecture of JavaScript, this project is aimed to facilitate the comprehension of EDA.

Usage Preview

A set of API is implemented quite similar to Event, EventTarget and EventListener in JavaScript.

Create an Event

// Create a custom event
Event event = new Event();
event.type = /* type string */;
event.args = /* any object */;
// then dispatch this event somewhere.

Add an Event Listener

// Create and instantiate an event target.
EventTarget target = new EventTarget() {};
// Create and implement an event listener.
EventListener listener = new EventListener() {
  @Override
  public void on(Event event) {
      switch(event.type) {
        case "event_type":
          // TODO: handle event typed of "event_type".
          break;
        default:
          break;
      }
  }
};
// Add event listeners
target.addEventListener("event_type", listener);
// Dispatch an event
target.dispatch(event);

Remove an Event Listener

// Remove a specific event listener
target.removeEventListener("event_type", listener);
// Remove all listeners of a specific event
target.removeEventListener("event_type");
// Remove all listeners
target.removeEventListener();

Implementation Preview

You can implement an event target from EventTarget or an event listener from EventListener.

Implement an Event Target

public class SampleEventTarget extends EventTarget {
  // TODO: dispatch an event somewhere.
  @Override
  public void dispatch(Event event) {
      // TODO: dispatch event.
  }
}

Implement an Event Listener

public class SampleEventListener extends EventListener {
  @Override
  public void on(event) {
      switch (event.type) {
        case "event_type":
          // TODO: handle event typed of "event_type".
          break;
        default:
          break;
      }
  }
}

Wrapper Preview

You can implement an event target wrapper from IEventTarget or an event listener wrapper from IEventHandler.

An Event Target Wrapper Implementing `IEventTarget`

public class SampleEventTargetWrapper implements IEventTarget {
  private EventTarget mEventTarget = new EventTarget {
  };

  @Override
  public void addEventListener(String type, IEventHandler listener) {
    mEventTarget.addEventListener(type, listener);
  }

  @Override
  public void removeEventListener(String type, IEventHandler listener) {
    mEventTarget.removeEventListener(type, listener)
  }

  @Override
  public void removeEventListener(String type) {
    mEventTarget.removeEventListener(type);
  }

  @Override
  public void dispatch(Event event) {
    mEventTarget.dispatch(event);
  }
}

An Event Listener Wrapper Implementing `IEventHandler`

public class SampleEventListenerWrapper implements IEventHandler {
  private EventListener mEventListener = new EventListener() {
    @Override
    public void on(Eevnt event) {
      switch (event.type) {
        case "event_type":
          // TODO: handle event typed of "event_type".
          break;
        default:
          break;
      }
    }
  };

  @Override
  public void invoke(Event event) {
    mEventListener.invoke(event);
  }

  @Override
  public void on(Event event) {
    mEventListener.on(event);
  }
}

License

MIT.

jingkecn/EventDrivenSystem