关于spring ioc容器的有关问题

关于spring ioc容器的问题


在spring的源代码中,有org.springframework.beans.factory.support.BeanDefinitionValueResolver这么个类.
在该类中有private Object resolveReference(String argName, RuntimeBeanReference ref)这样1个方法.

源代码如下:

private Object resolveReference(String argName, RuntimeBeanReference ref) {   
        if (this.beanFactory.logger.isTraceEnabled()) {   
            this.beanFactory.logger.trace("Resolving reference from property " + argName + " in bean '" +   
                    this.beanName + "' to bean '" + ref.getBeanName() + "'");   
        }   
        try {   
            if (ref.isToParent()) {   
                if (this.beanFactory.getParentBeanFactory() == null) {   
                    throw new BeanCreationException(   
                            this.beanDefinition.getResourceDescription(), this.beanName,   
                            "Can't resolve reference to bean '" + ref.getBeanName() +   
                            "' in parent factory: no parent factory available");   
                }   
                return this.beanFactory.getParentBeanFactory().getBean(ref.getBeanName());   
            }   
            else {   
                Object bean = this.beanFactory.getBean(ref.getBeanName());   
                if (this.beanDefinition.isSingleton()) {   
                    this.beanFactory.registerDependentBean(ref.getBeanName(), this.beanName);   
                }   
                return bean;   
            }   
        }   
        catch (BeansException ex) {   
            throw new BeanCreationException(   
                    this.beanDefinition.getResourceDescription(), this.beanName,   
                    "Cannot resolve reference to bean '" + ref.getBeanName() + "' while setting " + argName, ex);   
        }   
    }  

private Object resolveReference(String argName, RuntimeBeanReference ref) {
		if (this.beanFactory.logger.isTraceEnabled()) {
			this.beanFactory.logger.trace("Resolving reference from property " + argName + " in bean '" +
					this.beanName + "' to bean '" + ref.getBeanName() + "'");
		}
		try {
			if (ref.isToParent()) {
				if (this.beanFactory.getParentBeanFactory() == null) {
					throw new BeanCreationException(
							this.beanDefinition.getResourceDescription(), this.beanName,
							"Can't resolve reference to bean '" + ref.getBeanName() +
							"' in parent factory: no parent factory available");
				}
				return this.beanFactory.getParentBeanFactory().getBean(ref.getBeanName());
			}
			else {
				Object bean = this.beanFactory.getBean(ref.getBeanName());
				if (this.beanDefinition.isSingleton()) {
					this.beanFactory.registerDependentBean(ref.getBeanName(), this.beanName);
				}
				return bean;
			}
		}
		catch (BeansException ex) {
			throw new BeanCreationException(
					this.beanDefinition.getResourceDescription(), this.beanName,
					"Cannot resolve reference to bean '" + ref.getBeanName() + "' while setting " + argName, ex);
		}
	}

这个方法的大致作用是,取得bean所依赖的bean实例.但这里遇到问题了.ioc容器在这里做了1个依赖关系的map.但建立了这个依赖关系后,也没有具体使用到他的地方.难以理解设计者的思想.