public class ScorpiosEvent extends ApplicationEvent {
	private String msg;
	public ScorpiosEvent(Object source,String message) {
		super(source);
		this.msg = message;
	}
	public String getMsg() {
		return msg;
	}
	public void setMsg(String msg) {
		this.msg = msg;
	}
}

// ScorpiosListener
@Component
public class ScorpiosListener implements ApplicationListener {
	@Override
	public void onApplicationEvent(ApplicationEvent event) {
		if(event instanceof ScorpiosEvent){
			System.out.println("ScorpiosEvent ..." + ((ScorpiosEvent) event).getMsg());
		}else{
			System.out.println("ScorpiosEvent....dododododododododo");
		}
	}
}

// TestListener
@Component
public class TestListener implements ApplicationListener {
    @Override
    public void onApplicationEvent(ApplicationEvent event) {
        if(event instanceof ScorpiosEvent){
            System.out.println("TestListener ..." + ((ScorpiosEvent) event).getMsg());
        }else{
            System.out.println("TestListener....tttttttttttttttttttttt");
        }
    }
}

public static void main( String[] args )
{
    AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext();
    ac.register(AppConfig.class);
    ac.refresh();
    ScorpiosEvent scorpiosEvent = new ScorpiosEvent("scorpios","aaaaaaaaaa");
    ac.publishEvent(scorpiosEvent);
}

public void refresh() throws BeansException, IllegalStateException {
    synchronized (this.startupShutdownMonitor) {
        // 準(zhǔn)備工作，包括設(shè)置啟動(dòng)時(shí)間，是否激活標(biāo)識(shí)位，初始化屬性源(property source)配置
        prepareRefresh();
        // 返回一個(gè)factory 為什么需要返回一個(gè)工廠？ 因?yàn)橐獙?duì)工廠進(jìn)行初始化
        ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
        // 準(zhǔn)備工廠
        prepareBeanFactory(beanFactory);
        try {
            // 這個(gè)方法在當(dāng)前版本的spring是沒用任何代碼的，可能spring期待在后面的版本中去擴(kuò)展吧
            postProcessBeanFactory(beanFactory);
            // 調(diào)用BeanFactoryPostProcessors的后置處理器
            // 在Spring環(huán)境中去執(zhí)行已經(jīng)被注冊(cè)的FactoryProcessors
            // 設(shè)置執(zhí)行自定義的ProcessorBeanFactory和Spring內(nèi)部自己定義的
            invokeBeanFactoryPostProcessors(beanFactory);
            //-------------------到此spring工廠完成創(chuàng)建工作--------------------------
            // 注冊(cè)BeanPostProcessor后置處理器
            registerBeanPostProcessors(beanFactory);
            initMessageSource();
            // 初始化應(yīng)用事件廣播器
            initApplicationEventMulticaster();
            onRefresh();
            // 注冊(cè)監(jiān)聽器
            registerListeners();
            // 實(shí)例化單實(shí)例非懶加載的Bean
            finishBeanFactoryInitialization(beanFactory);
            // 此處會(huì)發(fā)布一個(gè)事件：ContextRefreshedEvent
            finishRefresh();
        } 
    }
}

protected void initApplicationEventMulticaster() {
    ConfigurableListableBeanFactory beanFactory = getBeanFactory();
    // 工廠里是否包含 “applicationEventMulticaster” Bean
    if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
        this.applicationEventMulticaster =
            beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
    } else {
        // 沒有的話，Spring自己創(chuàng)建一個(gè)SimpleApplicationEventMulticaster
        this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
        // 將自己創(chuàng)建的SimpleApplicationEventMulticaster放到Spring容器中，
        // name 為：applicationEventMulticaster
        beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
        }
    }
}

protected void registerListeners() {
    // 注冊(cè)靜態(tài)指定的監(jiān)聽器，沒有
    for (ApplicationListener<?> listener : getApplicationListeners()) {
        getApplicationEventMulticaster().addApplicationListener(listener);
    }
    // 從Spring容器中拿到所有實(shí)現(xiàn)了ApplicationListener接口的類，此處能拿到我們添加的兩個(gè)Listener
    String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
    for (String listenerBeanName : listenerBeanNames) {
        // 獲取上面創(chuàng)建的ApplicationEventMulticaster廣播器，把listenerBeanName放到廣播器中的
        // this.defaultRetriever.applicationListenerBeans這個(gè)集合中，注意此處是放的是listenerBeanName
        getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
    }
    Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
    this.earlyApplicationEvents = null;
    if (earlyEventsToProcess != null) {
        for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
            getApplicationEventMulticaster().multicastEvent(earlyEvent);
        }
    }
}

// ApplicationListenerDetector類
public Object postProcessAfterInitialization(Object bean, String beanName) {
    // 判斷當(dāng)前的Bean是不是實(shí)現(xiàn)了ApplicationListener接口
    // 這兩個(gè)ScorpiosListener、TestListener肯定是的啊
    // 此處的Bean已經(jīng)實(shí)例化好了
    if (bean instanceof ApplicationListener) {
        Boolean flag = this.singletonNames.get(beanName);
        if (Boolean.TRUE.equals(flag)) {
            // 將這個(gè)實(shí)現(xiàn)了ApplicationListener接口的Bean放到廣播器的
            // this.defaultRetriever.applicationListeners屬性中
            this.applicationContext.addApplicationListener((ApplicationListener<?>) bean);
        } else if (Boolean.FALSE.equals(flag)) {
            this.singletonNames.remove(beanName);
        }
    }
    return bean;
}

// AbstractApplicationContext類中方法
public void addApplicationListener(ApplicationListener<?> listener) {
    if (this.applicationEventMulticaster != null) {
        this.applicationEventMulticaster.addApplicationListener(listener);
    }
    this.applicationListeners.add(listener);
}
// AbstractApplicationEventMulticaster類中方法
public void addApplicationListener(ApplicationListener<?> listener) {
    synchronized (this.retrievalMutex) {
        Object singletonTarget = AopProxyUtils.getSingletonTarget(listener);
        if (singletonTarget instanceof ApplicationListener) {
            this.defaultRetriever.applicationListeners.remove(singletonTarget);
        }
        // 將listener放到廣播器的屬性中了?。。。?！
        this.defaultRetriever.applicationListeners.add(listener);
        this.retrieverCache.clear();
    }
}

protected void finishRefresh() {
    clearResourceCaches();
    initLifecycleProcessor();
    getLifecycleProcessor().onRefresh();
    // 發(fā)布事件，就關(guān)注這一個(gè)方法?。。?！
    publishEvent(new ContextRefreshedEvent(this));
    LiveBeansView.registerApplicationContext(this);
}

protected void publishEvent(Object event, @Nullable ResolvableType eventType) {
    ApplicationEvent applicationEvent;
    // 判斷這個(gè)event是不是ApplicationEvent實(shí)例
    if (event instanceof ApplicationEvent) {
        applicationEvent = (ApplicationEvent) event;
    } else {
        applicationEvent = new PayloadApplicationEvent<>(this, event);
        if (eventType == null) {
            eventType = ((PayloadApplicationEvent<?>) applicationEvent).getResolvableType();
        }
    }
    if (this.earlyApplicationEvents != null) {
        this.earlyApplicationEvents.add(applicationEvent);
    } else {
        // 拿到廣播器，然后調(diào)用廣播器的multicastEvent()方法
        getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);
    }
    if (this.parent != null) {
        if (this.parent instanceof AbstractApplicationContext) {
            ((AbstractApplicationContext) this.parent).publishEvent(event, eventType);
        } else {
            this.parent.publishEvent(event);
        }
    }
}

// 此方法拿到之前創(chuàng)建的廣播器applicationEventMulticaster
// 還記得是什么類型的嘛？對(duì)，是它：SimpleApplicationEventMulticaster
ApplicationEventMulticaster getApplicationEventMulticaster() throws IllegalStateException {
    if (this.applicationEventMulticaster == null) {
		// 拋異常代碼略
    }
    return this.applicationEventMulticaster;
}

public void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {
    ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));
    Executor executor = getTaskExecutor();
    // 此getApplicationListeners(event, type)方法就是拿到廣播器里面的所有Listener
    for (ApplicationListener<?> listener : getApplicationListeners(event, type)) {
        if (executor != null) {
            executor.execute(() -> invokeListener(listener, event));
        } else {
            // 調(diào)用監(jiān)聽器的方法！?。?！
            invokeListener(listener, event);
        }
    }
}
protected void invokeListener(ApplicationListener<?> listener, ApplicationEvent event) {
    ErrorHandler errorHandler = getErrorHandler();
    if (errorHandler != null) {
        doInvokeListener(listener, event);     
    } else {
        // 參數(shù)傳入的是listener,終于開始調(diào)用了！?。?！
        doInvokeListener(listener, event);
    }
}
private void doInvokeListener(ApplicationListener listener, ApplicationEvent event) {
    try {
        // 調(diào)用Listener中僅有的onApplicationEvent()方法?。?！
        listener.onApplicationEvent(event);
    } catch (ClassCastException ex) {
     	// 拋異常代碼略  
    }
}