ApplicationContextAwareProcessor

ApplicationContextAwareProcessor可用来处理实现ApplicationContextAware的bean对象,
获取到ApplicationContext对象.

关键源码

 

public Object postProcessBeforeInitialization(final Object bean, String beanName) throws BeansException {
   AccessControlContext acc = null;

   if (System.getSecurityManager() != null &&
         (bean instanceof EnvironmentAware
               || bean instanceof EmbeddedValueResolverAware
               || bean instanceof ResourceLoaderAware
               || bean instanceof ApplicationEventPublisherAware
               || bean instanceof MessageSourceAware
               || bean instanceof ApplicationContextAware)) {
      acc = this.applicationContext.getBeanFactory().getAccessControlContext();
   }

   if (acc != null) {
      AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
         invokeAwareInterfaces(bean);
         return null;
      }, acc);
   }
   else {
      invokeAwareInterfaces(bean);
   }

   return bean;
}

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);
      }

      /**
       * bean实现ApplicationContextAware可获取applicationContext对象
       */
      if (bean instanceof ApplicationContextAware) {
         ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
      }
   }
}

例子

@Component
public class ApplicationContextAwareImpl implements ApplicationContextAware {
    private ApplicationContext applicationContext;
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext=applicationContext;
        System.out.println(applicationContext);
    }
}