public class MyEventObject extends EventObject {

 private String eventName ;
 
 public MyEventObject (Object source, String eventName) {
  
  super(source);
  this.setEventName(eventName);
 }

 public String getEventName() {
  return eventName;
 }

 public void setEventName(String eventName) {
  this.eventName = eventName;
 }

 private static final long serialVersionUID = 8374250957018011175L;
}

public interface MyEventListener extends EventListener {

 public void myEvent(MyEventObject eventObject);
}

public class MyEventListenerImpl implements MyEventListener {

 @Override
 public void myEvent(MyEventObject eventObject) {

  System.out.println("MyEventListenerImpl --- " + eventObject.getEventName());
 }
}

public class MyEventSource {

 private Set<MyEventListener> myEventListeners = new HashSet<>();
 
 public void addListener(MyEventListener listener){
  
  this.myEventListeners.add(listener);
 }
 
 public void removeListener(MyEventListener listener){
  
  this.myEventListeners.remove(listener);
 }
 
 public void pushEvent(){
  //dosomething
  //發(fā)布push event消息
  notifyListener(new MyEventObject(this, "push event"));
 }
 
 private void notifyListener(MyEventObject eventObject){
  
  for (MyEventListener myEventListener : myEventListeners) {
   myEventListener.myEvent(eventObject);
  }
 }
}

public static void main(String[] args) {
 
 MyEventSource myEventSource = new MyEventSource();
 
 MyEventListenerImpl myEventListenerImpl = new MyEventListenerImpl();
 
 myEventSource.addListener(myEventListenerImpl);
 
 myEventSource.pushEvent();
}

public final class LifecycleEvent extends EventObject {

 //......

 public LifecycleEvent(Lifecycle lifecycle, String type, Object data) {

  super(lifecycle);
  this.type = type;
  this.data = data;
 }

 //......
}

public interface Lifecycle {
 /**
  * The LifecycleEvent type for the "component after init" event.
  */
 public static final String BEFORE_INIT_EVENT = "before_init";

 /**
  * The LifecycleEvent type for the "component after init" event.
  */
 public static final String AFTER_INIT_EVENT = "after_init";

 /**
  * The LifecycleEvent type for the "component start" event.
  */
 public static final String START_EVENT = "start";

 //......
}

public interface LifecycleListener {

 public void lifecycleEvent(LifecycleEvent event);
}

public class ContextConfig implements LifecycleListener {
 
 //......
 @Override
 public void lifecycleEvent(LifecycleEvent event) {

  // Identify the context we are associated with
  try {
   context = (Context) event.getLifecycle();
  } catch (ClassCastException e) {
   log.error(sm.getString("contextConfig.cce", event.getLifecycle()), e);
   return;
  }

  // Process the event that has occurred
  if (event.getType().equals(Lifecycle.CONFIGURE_START_EVENT)) {
   configureStart();
  } else if (event.getType().equals(Lifecycle.BEFORE_START_EVENT)) {
   beforeStart();
  } else if (event.getType().equals(Lifecycle.AFTER_START_EVENT)) {
   // Restore docBase for management tools
   if (originalDocBase != null) {
    context.setDocBase(originalDocBase);
   }
  } else if (event.getType().equals(Lifecycle.CONFIGURE_STOP_EVENT)) {
   configureStop();
  } else if (event.getType().equals(Lifecycle.AFTER_INIT_EVENT)) {
   init();
  } else if (event.getType().equals(Lifecycle.AFTER_DESTROY_EVENT)) {
   destroy();
  }
 }

 //......
}

public final class LifecycleSupport {

 //......

 //監(jiān)聽(tīng)對(duì)象集合
 private LifecycleListener listeners[] = new LifecycleListener[0];
 
 private final Object listenersLock = new Object(); // Lock object for changes to listeners

 //添加監(jiān)聽(tīng)對(duì)象
 public void addLifecycleListener(LifecycleListener listener) {

  synchronized (listenersLock) {
   LifecycleListener results[] =
   new LifecycleListener[listeners.length + 1];
   for (int i = 0; i < listeners.length; i++)
    results[i] = listeners[i];
   results[listeners.length] = listener;
   listeners = results;
  }

 }

 //發(fā)布監(jiān)聽(tīng)對(duì)象
 public void fireLifecycleEvent(String type, Object data) {

  LifecycleEvent event = new LifecycleEvent(lifecycle, type, data);
  LifecycleListener interested[] = listeners;
  for (int i = 0; i < interested.length; i++)
   interested[i].lifecycleEvent(event);

 }

 //移除監(jiān)聽(tīng)對(duì)象
 public void removeLifecycleListener(LifecycleListener listener) {

  synchronized (listenersLock) {
   int n = -1;
   for (int i = 0; i < listeners.length; i++) {
    if (listeners[i] == listener) {
     n = i;
     break;
    }
   }
   if (n < 0)
    return;
   LifecycleListener results[] =
    new LifecycleListener[listeners.length - 1];
   int j = 0;
   for (int i = 0; i < listeners.length; i++) {
    if (i != n)
     results[j++] = listeners[i];
   }
   listeners = results;
  }
 }
}

public abstract class LifecycleBase implements Lifecycle{

 //......
 private LifecycleSupport lifecycle = new LifecycleSupport(this);

 @Override
 public void addLifecycleListener(LifecycleListener listener) {
  lifecycle.addLifecycleListener(listener);
 }

 @Override
 public void removeLifecycleListener(LifecycleListener listener) {
  lifecycle.removeLifecycleListener(listener);
 }

 protected void fireLifecycleEvent(String type, Object data) {
  lifecycle.fireLifecycleEvent(type, data);
 }
 //......
}

fireLifecycleEvent(Lifecycle.CONFIGURE_STOP_EVENT, null);

public abstract class ApplicationEvent extends EventObject {

 //......
 public ApplicationEvent(Object source) {
  super(source);
  this.timestamp = System.currentTimeMillis();
 }
 //......
}

public abstract class ApplicationContextEvent extends ApplicationEvent {
 public ApplicationContextEvent(ApplicationContext source) {
  super(source);
 }

 public final ApplicationContext getApplicationContext() {
  return (ApplicationContext)this.getSource();
 }
}

public class ContextStartedEvent extends ApplicationContextEvent {
 public ContextStartedEvent(ApplicationContext source) {
  super(source);
 }
}

public interface ApplicationListener<E extends ApplicationEvent> extends EventListener {

 void onApplicationEvent(E event);
}

public class MyApplicationListener implements ApplicationListener<ApplicationEvent> {

 @Override
 public void onApplicationEvent(ApplicationEvent applicationEvent) {

  if (applicationEvent instanceof ContextRefreshedEvent){

   System.out.println("context refresh!"); 
  }
 }
}

protected void finishRefresh() {
 
 //......
 // Publish the final event.
 publishEvent(new ContextRefreshedEvent(this));
}

protected void publishEvent(Object event, @Nullable ResolvableType eventType) {

 //......
 getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);
 //......
}

publishEvent方法通過(guò)調(diào)用一個(gè)默認(rèn)的多播器SimpleApplicationEventMulticaster的multicastEvent方法來(lái)發(fā)布各種事件：

SimpleApplicationEventMulticaster
public void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {
 ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));

 //通過(guò)getApplicationListeners獲取了所有監(jiān)聽(tīng)器，然后通過(guò)invokeListener方法循環(huán)發(fā)布事件
 for (final ApplicationListener<?> listener : getApplicationListeners(event, type)) {
  Executor executor = getTaskExecutor();
  if (executor != null) {
   executor.execute(() -> invokeListener(listener, event));
  }
  else {
   invokeListener(listener, event);
  }
 }
}

protected void invokeListener(ApplicationListener<?> listener, ApplicationEvent event) {
 //......
 doInvokeListener(listener, event);
}

private void doInvokeListener(ApplicationListener listener, ApplicationEvent event) {
 //......
 listener.onApplicationEvent(event);
}

applicationContext.publishEvent(new ApplicationEvent(new String("事件發(fā)布")) { });