Spring中的Aware接口详细解析

package org.springframework.beans.factory;
/**
 * A marker superinterface indicating that a bean is eligible to be notified by the
 * Spring container of a particular framework object through a callback-style method.
 * The actual method signature is determined by individual subinterfaces but should
 * typically consist of just one void-returning method that accepts a single argument.
 *
 * <p>Note that merely implementing {@link Aware} provides no default functionality.
 * Rather, processing must be done explicitly, for example in a
 * {@link org.springframework.beans.factory.config.BeanPostProcessor}.
 * Refer to {@link org.springframework.context.support.ApplicationContextAwareProcessor}
 * for an example of processing specific {@code *Aware} interface callbacks.
 *
 * @author Chris Beams
 * @author Juergen Hoeller
 * @since 3.1
 */
public interface Aware {
}

public interface ApplicationContextAware extends Aware {
	void setApplicationContext(ApplicationContext applicationContext) throws BeansException;
}

@Component
public class ApplicationContextStaticProvider implements ApplicationContextAware {
	private static ApplicationContext context;
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		context = applicationContext;
	}
	public static ApplicationContext getApplicationContext() {
		return context;
	}
	/**
	 * 通过beanName获取Bean
	 *
	 * @param beanName
	 * @return
	 */
	public static Object getBean(String beanName) {
		return getApplicationContext().getBean(beanName);
	}
	/**
	 * 通过class获取bean
	 *
	 * @param clazz
	 * @param <T>
	 * @return
	 */
	public static <T> T getBean(Class<T> clazz) {
		return getApplicationContext().getBean(clazz);
	}
	/**
	 * 通过name,以及Clazz返回指定的bean
	 *
	 * @param beanName
	 * @param clazz
	 * @param <T>
	 * @return
	 */
	public static <T> T getBean(String beanName, Class<T> clazz) {
		return getApplicationContext().getBean(beanName, clazz);
	}
}
@Service
public class DemoBean {
	public void test(String str){
		System.out.println(str);
	}
}
public class AnnotationConfigApplicationContextTests {
	@Test
	public void scanAndRefreshTestAware() {
		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
		context.scan("org.springframework.context.annotation7");
		context.refresh();
		DemoBean demoBean= (DemoBean) ApplicationContextStaticProvider.getBean("demoBean");
		demoBean.test("test applicationContextAware");
	}
}

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);
			}
			// 最终调用ApplicationContextAware.setApplicationContext()方法
			if (bean instanceof ApplicationContextAware) {
				((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
			}
		}
	}

private void invokeAwareMethods(final String beanName, final Object bean) {
		if (bean instanceof Aware) {
			if (bean instanceof BeanNameAware) {
				((BeanNameAware) bean).setBeanName(beanName);
			}
			if (bean instanceof BeanClassLoaderAware) {
				ClassLoader bcl = getBeanClassLoader();
				if (bcl != null) {
					((BeanClassLoaderAware) bean).setBeanClassLoader(bcl);
				}
			}
			if (bean instanceof BeanFactoryAware) {
				((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
			}
		}
	}