//事件:用于封裝事件源及一些與事件相關(guān)的參數(shù).
class CurrentEvent extends EventObject {
  private Object source;//事件源

  public CurrentEvent(Object source) {
    super(source);
    this.source = source;
  }

  public Object getSource() {
    return source;
  }

  public void setSource(Object source) {
    this.source = source;
  }
}
//事件源：
class EventSource {
  private String name;
  //監(jiān)聽(tīng)器容器
  private List<CurrentEventListener> listeners;

  public EventSource() {
    this.listeners = new ArrayList<>();
    this.name = "默認(rèn)";
  }
  //給事件源注冊(cè)監(jiān)聽(tīng)器
  public void addEventListener(CurrentEventListener eventListener) {
    listeners.add(eventListener);
  }

  public String getName() {
    return name;
  }
  //模擬事件觸發(fā)器，當(dāng)成員變量的值發(fā)生變化時(shí)，觸發(fā)事件
  public void setName(String name) {
    if(!this.name.equals(name)) {
      this.name = name;
      notifies();
    }
  }
  //當(dāng)事件發(fā)生時(shí),通知注冊(cè)在該事件源上的所有監(jiān)聽(tīng)器做出相應(yīng)的反應(yīng)（調(diào)用回調(diào)方法）
  private void notifies(){
    CurrentEventListener eventListener = null;
    Iterator<CurrentEventListener> iterator = this.listeners.iterator();
    while(iterator.hasNext()){
      eventListener = iterator.next();
      eventListener.handleEvent(new CurrentEvent(this));
    }
  }
}
//事件監(jiān)聽(tīng)器：實(shí)現(xiàn)java.util.EventListener接口。
// 定義事件處理方法,事件源發(fā)生相應(yīng)的事件時(shí)會(huì)調(diào)用這個(gè)方法。
class CurrentEventListener implements EventListener {
  //事件發(fā)生后的回調(diào)方法
  public void handleEvent(CurrentEvent e){
    EventSource Object = (EventSource)e.getSource();
    System.out.println("注意！默認(rèn)名稱被改變了");
    System.out.println("新名字叫 \""+Object.getName()+"\"");
  }
}

public class EventMechanism {
  public static void main(String[] args) {
    EventSource eventSource = new EventSource();
    //注冊(cè)監(jiān)聽(tīng)器
    eventSource.addEventListener(new CurrentEventListener());
    //觸發(fā)事件
    eventSource.setName("測(cè)試");
  }
}