public interface InitializingBean {
/**
* Invoked by a BeanFactory after it has set all bean properties supplied
* (and satisfied BeanFactoryAware and ApplicationContextAware).
* <p>This method allows the bean instance to perform initialization only
* possible when all bean properties have been set and to throw an
* exception in the event of misconfiguration.
* @throws Exception in the event of misconfiguration (such
* as failure to set an essential property) or if initialization fails.
*/
void afterPropertiesSet() throws Exception;
}
如果想在bean初始化的时候做一些操作，则可以继承自InitializingBean 接口；
这个接口只有一个方法就是afterPropertiesSet 作用就是当bean的各个属性初始化之后，会调用此方法
spring的具体实现是在AbstractAutowireCapableBeanFactory类中 invokeInitMethods方法会调用 afterPropertiesSet
BeanNameAware 获得到容器中Bean的名称
BeanFactoryAware 获得当前bean Factory,从而调用容器的服务
ApplicationContextAware 当前的application context从而调用容器的服务
MessageSourceAware 得到message source从而得到文本信息
ApplicationEventPublisherAware 应用时间发布器,用于发布事件
ResourceLoaderAware 获取资源加载器,可以获得外部资源文件