标签：led get iat new creation dep cte dubbo 方法
ReferenceAnnotationBeanPostProcessor继承了AnnotationInjectedBeanPostProcessors其实现了InstantiationAwareBeanPostProcessorAdapter接口postProcessPropertyValues方法中，扫描带@Reference注解的成员 注入ReferenceBean对象：
@Override public PropertyValues postProcessPropertyValues( PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeanCreationException { InjectionMetadata metadata = findInjectionMetadata(beanName, bean.getClass(), pvs); try { metadata.inject(bean, beanName, pvs); } catch (BeanCreationException ex) { throw ex; } catch (Throwable ex) { throw new BeanCreationException(beanName, "Injection of @" + getAnnotationType().getName() + " dependencies is failed", ex); } return pvs; }
findInjectionMetadata会找出所有@Reference的字段和方法并封装成元数据，metadata.inject方法进去，会调用injectElement的inject方法，进而调用AnnotatedFieldElement的inject方法：
public class AnnotatedFieldElement extends InjectionMetadata.InjectedElement { private final Field field; private final A annotation; private volatile Object bean; protected AnnotatedFieldElement(Field field, A annotation) { super(field, null); this.field = field; this.annotation = annotation; } @Override protected void inject(Object bean, String beanName, PropertyValues pvs) throws Throwable { Class<?> injectedType = field.getType(); Object injectedObject = getInjectedObject(annotation, bean, beanName, injectedType, this); ReflectionUtils.makeAccessible(field); field.set(bean, injectedObject); } }
protected Object getInjectedObject(A annotation, Object bean, String beanName, Class<?> injectedType, InjectionMetadata.InjectedElement injectedElement) throws Exception { String cacheKey = buildInjectedObjectCacheKey(annotation, bean, beanName, injectedType, injectedElement); Object injectedObject = injectedObjectsCache.get(cacheKey); if (injectedObject == null) { injectedObject = doGetInjectedBean(annotation, bean, beanName, injectedType, injectedElement); // Customized inject-object if necessary injectedObjectsCache.putIfAbsent(cacheKey, injectedObject); } return injectedObject; }
其中doGetInjectedBean被ReferenceAnnotationBeanPostProcessor重写：
@Override protected Object doGetInjectedBean(Reference reference, Object bean, String beanName, Class<?> injectedType, InjectionMetadata.InjectedElement injectedElement) throws Exception { String referencedBeanName = buildReferencedBeanName(reference, injectedType); ReferenceBean referenceBean = buildReferenceBeanIfAbsent(referencedBeanName, reference, injectedType, getClassLoader()); cacheInjectedReferenceBean(referenceBean, injectedElement); Object proxy = buildProxy(referencedBeanName, referenceBean, injectedType); return proxy; }
可以看到这里构造了一个referenceBean并返回了一个代理，真正注入的其实是这个代理
标签：led get iat new creation dep cte dubbo 方法
原文地址：https://www.cnblogs.com/lccsblog/p/11627253.html
