Spring中提供了各种Aware接口，方便从上下文中获取当前的运行环境，比较常见的几个子接口有：BeanFactoryAware,BeanNameAware,ApplicationContextAware,EnvironmentAware，BeanClassLoaderAware等
这些Aware的作用都可以从命名得知
Aware的处理
其中BeanNameAware、BeanClassLoaderAware和BeanFactoryAware这三个是直接在bean的初始化之前就处理了的，具体代码在AbstractAutowireCapableBeanFactory.initializeBean方法中：
protected Object initializeBean(String beanName, Object bean, RootBeanDefinition mbd) {
// 判断对象实现的接口类型，处理特定的三种接口类型：BeanNameAware、BeanClassLoaderAware和BeanFactoryAware。
if (bean instanceof BeanNameAware) {
((BeanNameAware) bean).setBeanName(beanName);
}
if (bean instanceof BeanClassLoaderAware) {
((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());
}
if (bean instanceof BeanFactoryAware) {
((BeanFactoryAware) bean).setBeanFactory(this);
}
// 开始Bean初始化前处理、初始化、初始化后处理
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}除了这三种之外的那些Aware接口的实现就不太一样了，它们都是利用BeanPostProcessor接口完成的，关于BeanPostProcessor接口的原理可以这篇文章：Spring扩展点之BeanPostProcessor
如ApplicationContextAware就是利用ApplicationContextAwareProcessor实现的：
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>) () -> {
//具体实现
invokeAwareInterfaces(bean);
return null;
}, acc);
}
else {
//具体实现
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);
}
if (bean instanceof ApplicationContextAware) {
((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
}
}
}而ApplicationContextAwareProcessor的注册奥秘在AbstractApplicationContext.prepareBeanFactory方法中：
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this));
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);转载：https://blog.csdn.net/javaxuexilu/article/details/100912885
查看评论