Spring之Bean实现了ApplicationContextAware等aware接口,对于setApplicationContext方法执行时间点的说明

  在Spring中，如果Bean对象实现了ApplicationContextAware接口,则Spring在完成Bean的初始化后,会将ApplicationContext上下文对象注入至该Bean对象中,注入方法为调用Bean的setApplicationContext方法,如:

public class BeanAwareTest implement ApplicationContextAware {

   private static ApplicationContext applicationContext;
    public void setApplicationContext(ApplicationContext applicationContext) {        

        SpringContextHolder.applicationContext = applicationContext;   

    }     

}

那么上面的setApplicationContext方法是什么时间被执行的呢?

  我们通过对spring源码进行追踪，发现AbstractApplicationContext类中的prepareBeanFactory方法有一句

     beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));

  该方法中涉及一个类ApplicationContextAwareProcessor,该类中有初始化方法

    postProcessBeforeInitialization中有一句this.invokeAwareInterfaces(bean),

  而invokeAwareInterfaces方法的代码如下: 

private void invokeAwareInterfaces(Object bean) {    if(bean instanceof Aware) {        if(bean instanceof EnvironmentAware) {            ((EnvironmentAware)bean).setEnvironment(this.applicationContext.getEnvironment());        }        if(bean instanceof EmbeddedValueResolverAware) {            ((EmbeddedValueResolverAware)bean).setEmbeddedValueResolver(this.embeddedValueResolver);        }        if(bean instanceof ResourceLoaderAware) {            ((ResourceLoaderAware)bean).setResourceLoader(this.applicationContext);        }        if(bean instanceof ApplicationEventPublisherAware) {            ((ApplicationEventPublisherAware)bean).setApplicationEventPublisher(this.applicationContext);        }        if(bean instanceof MessageSourceAware) {            ((MessageSourceAware)bean).setMessageSource(this.applicationContext);        }        if(bean instanceof ApplicationContextAware) {            ((ApplicationContextAware)bean).setApplicationContext(this.applicationContext);        }    }

}

示例调用序列图: