IOC 容器启动过程 10 - registerListeners

工作内容

查找并注册监听器。

protected void registerListeners() {
    // Register statically specified listeners first.
    // 注册来自 prepareRefresh 阶段注册的监听器
    for (ApplicationListener<?> listener : getApplicationListeners()) {
        getApplicationEventMulticaster().addApplicationListener(listener);
    }
    // Do not initialize FactoryBeans here: We need to leave all regular beans
    // uninitialized to let post-processors apply to them!
    // 注册通过接口注册的监听器
    String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
    for (String listenerBeanName : listenerBeanNames) {
        getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
    }
    // Publish early application events now that we finally have a multicaster...
    // 发布消息
    Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
    this.earlyApplicationEvents = null;
    if (!CollectionUtils.isEmpty(earlyEventsToProcess)) {
        for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
            getApplicationEventMulticaster().multicastEvent(earlyEvent);
        }
    }
}