Spring源码情操陶冶-AbstractApplicationContext#initApplicationEventMulticaster

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承接前文Spring源码情操陶冶-AbstractApplicationContext#initMessageSource

约定web.xml配置的contextClass为默认值XmlWebApplicationContext

瞧瞧官方注释

/** * Initialize the ApplicationEventMulticaster. * Uses SimpleApplicationEventMulticaster if none defined in the context. * @see org.springframework.context.event.SimpleApplicationEventMulticaster */

初始化ApplicationEventMulticaster事件，默认使用SimpleApplicationEventMulticaster事件

直接源码

protected void initApplicationEventMulticaster() { ConfigurableListableBeanFactory beanFactory = getBeanFactory(); //查找是否存在id为applicationEventMulticaster的bean对象 if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) { this.applicationEventMulticaster = beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class); if (logger.isDebugEnabled()) { logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]"); } } else { //默认使用SimpleApplicationEventMulticaster，并注册为单例 this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory); beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster); if (logger.isDebugEnabled()) { logger.debug("Unable to locate ApplicationEventMulticaster with name '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "': using default [" + this.applicationEventMulticaster + "]"); } } }