ApplicationListenerDetector監聽器判斷demo
Bean實例化之後
判斷Bean是否是監聽器,如果是監聽器就將當前Bean加入監聽器集合
public Object postProcessAfterInitialization(Object bean, String beanName) { if (bean instanceof ApplicationListener) { // potentially not detected as a listener by getBeanNamesForType retrieval Boolean flag = this.singletonNames.get(beanName); if (Boolean.TRUE.equals(flag)) { // singleton bean (top-level or inner): register on the fly this.applicationContext.addApplicationListener((ApplicationListener<?>) bean); } else if (Boolean.FALSE.equals(flag)) { if (logger.isWarnEnabled() && !this.applicationContext.containsBean(beanName)) { // inner bean with other scope - can't reliably process events logger.warn("Inner bean '" + beanName + "' implements ApplicationListener interface " + "but is not reachable for event multicasting by its containing ApplicationContext " + "because it does not have singleton scope. Only top-level listener beans are allowed " + "to be of non-singleton scope."); } this.singletonNames.remove(beanName); } } return bean; }
Bean銷毀之前
如果當前Bean是監聽器,就將當前Bean從監聽器集合中移除
public void postProcessBeforeDestruction(Object bean, String beanName) { if (bean instanceof ApplicationListener) { try { ApplicationEventMulticaster multicaster = this.applicationContext.getApplicationEventMulticaster(); multicaster.removeApplicationListener((ApplicationListener<?>) bean); multicaster.removeApplicationListenerBean(beanName); } catch (IllegalStateException ex) { // ApplicationEventMulticaster not initialized yet - no need to remove a listener } } }
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