@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();

        // Tell the subclass to refresh the internal bean factory.  
        ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

        // Prepare the bean factory for use in this context.  
        prepareBeanFactory(beanFactory);

        try {  
            // Allows post-processing of the bean factory in context subclasses.  
            postProcessBeanFactory(beanFactory);

            // Invoke factory processors registered as beans in the context.  
            invokeBeanFactoryPostProcessors(beanFactory);

            // Register bean processors that intercept bean creation.  
            registerBeanPostProcessors(beanFactory);

            // Initialize message source for this context.  
            initMessageSource();

            // Initialize event multicaster for this context.  
            initApplicationEventMulticaster();

            // Initialize other special beans in specific context subclasses.  
            onRefresh();

            // Check for listener beans and register them.  
            registerListeners();

            // Instantiate all remaining (non-lazy-init) singletons.  
            finishBeanFactoryInitialization(beanFactory);

            // Last step: publish corresponding event.  
            finishRefresh();  
        }

        catch (BeansException ex) {  
            if (logger.isWarnEnabled()) {  
                logger.warn("Exception encountered during context initialization - " +  
                        "cancelling refresh attempt: " + ex);  
            }

            // Destroy already created singletons to avoid dangling resources.  
            destroyBeans();

            // Reset 'active' flag.  
            cancelRefresh(ex);

            // Propagate exception to caller.  
            throw ex;  
        }

        finally {  
            // Reset common introspection caches in Spring's core, since we  
            // might not ever need metadata for singleton beans anymore...  
            resetCommonCaches();  
        }  
    }  
}

包括BeanDefinition的Resource定位，载入，注册三个基本过程

三个过程分开，并使用不同的模块来完成，如何使用相应的ResourceLoader，BeanDefinitionReader等模块，通过这样的设计方式，可以让用户更加啊灵活的对这三个过程进行剪裁或扩展