Spring ContextAnnotationAutowireCandidateResolver

@Override
@Nullable
public Object getLazyResolutionProxyIfNecessary(DependencyDescriptor descriptor, @Nullable String beanName) {
   // 判断是否懒加载
   return (isLazy(descriptor) ? buildLazyResolutionProxy(descriptor, beanName) : null);
}

// 第一部分
// 获取注解循环
for (Annotation ann : descriptor.getAnnotations()) {
   // 得到 lazy 注解
   Lazy lazy = AnnotationUtils.getAnnotation(ann, Lazy.class);
   // 判断 lazy 的注解值是否 true
   if (lazy != null && lazy.value()) {
      return true;
   }
}

// 第二部分
// 获取方法参数对象
MethodParameter methodParam = descriptor.getMethodParameter();
if (methodParam != null) {
   // 获取 method
   Method method = methodParam.getMethod();
   if (method == null || void.class == method.getReturnType()) {
      // method 上寻找 lazy 注解
      Lazy lazy = AnnotationUtils.getAnnotation(methodParam.getAnnotatedElement(), Lazy.class);
      return lazy != null && lazy.value();
   }
}
return false;

/**
 * 创建延迟代理类
 */
protected Object buildLazyResolutionProxy(final DependencyDescriptor descriptor, final @Nullable String beanName) {
   Assert.state(getBeanFactory() instanceof DefaultListableBeanFactory,
         "BeanFactory needs to be a DefaultListableBeanFactory");
   final DefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory) getBeanFactory();
   // target source 接口 目标对象
   TargetSource ts = new TargetSource() {
      @Override
      public Class<?> getTargetClass() {
         return descriptor.getDependencyType();
      }

      @Override
      public boolean isStatic() {
         return false;
      }

      @Override
      public Object getTarget() {
         // DefaultListableBeanFactory 中 doResolveDependency 调用
         Object target = beanFactory.doResolveDependency(descriptor, beanName, null, null);
         // 为空的情况下根据类型返回空对象
         if (target == null) {
            Class<?> type = getTargetClass();
            if (Map.class == type) {
               return Collections.emptyMap();
            }
            else if (List.class == type) {
               return Collections.emptyList();
            }
            else if (Set.class == type || Collection.class == type) {
               return Collections.emptySet();
            }
            throw new NoSuchBeanDefinitionException(descriptor.getResolvableType(),
                  "Optional dependency not present for lazy injection point");
         }
         return target;
      }

      @Override
      public void releaseTarget(Object target) {
      }
   };
   // 代理工厂
   ProxyFactory pf = new ProxyFactory();
   // 设置数据信息
   pf.setTargetSource(ts);
   Class<?> dependencyType = descriptor.getDependencyType();
   if (dependencyType.isInterface()) {
      pf.addInterface(dependencyType);
   }
   // 代理工厂创建对象
   return pf.getProxy(beanFactory.getBeanClassLoader());
}