【spring源码学习】spring的事件发布监听机制源码解析

【一】相关源代码类

（1）spring的事件发布监听机制的核心管理类：org.springframework.context.event.SimpleApplicationEventMulticaster.

　　=>该类的初始化是放在项目加载时，在ioc容器xml配置文件解析加载完毕后，注册bean创建前后置处理实现类（BeanPostProcessor 接口实现），beanFactory配置处理（BeanFactoryPostProcessor接口实现）后，初始化该事件发布监听机制的核心类。

public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            // Prepare this context for refreshing.
            prepareRefresh();

            // 解析xml配置文件
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            // Prepare the bean factory for use in this context.
            prepareBeanFactory(beanFactory);

            try {
                // 注册未来bean实例化的前后置处理的PostProcessor接口实现
                postProcessBeanFactory(beanFactory);

                //执行所有实现BeanFactoryPostProcessor接口实现，对beanFactory进行处理
                invokeBeanFactoryPostProcessors(beanFactory);

                //  注册未来bean实例化的前后置处理的PostProcessor接口实现
                registerBeanPostProcessors(beanFactory);

                // 注册未来bean实例化的前后置处理的PostProcessor接口实现
                initMessageSource();

                // 实例化spring事件发布监听机制的核心类，SimpleApplicationEventMulticaster
                initApplicationEventMulticaster();

                // Initialize other special beans in specific context subclasses.
                onRefresh();

                // 注册事件监听器
                registerListeners();

                // 实例化非懒加载的bean,完成ioc容器中bean的实例化和反转依赖，并在内部实现动态代理相关的操作
                finishBeanFactoryInitialization(beanFactory);

                // Last step: publish corresponding event.
                finishRefresh();
            }

            catch (BeansException ex) {
                logger.warn("Exception encountered during context initialization - cancelling refresh attempt", ex);

                // Destroy already created singletons to avoid dangling resources.
                destroyBeans();

                // Reset 'active' flag.
                cancelRefresh(ex);

                // Propagate exception to caller.
                throw ex;
            }
        }
    }

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