在AbstractApplicationContext.refresh();的過程中，第二步為獲取BeanFactory ->obtainFreshBeanFactory()。在這個方法中，Spring先建立了BeanFactory，然後通過讀取XML配置檔案（或者掃描Java類）的方式初始化了BeanDefinition。這裡面就包括Spring Bean的主要資訊，例如依賴情況、作用域等等。

    @Override
    public void refresh() throws BeansException, IllegalStateException {
        
 
synchronized (this.startupShutdownMonitor) {
            // (1)Prepare this context for refreshing.
            prepareRefresh();

            // (2)Tell the subclass to refresh the internal bean factory.
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            ......
    }    
 

一、obtainFreshBeanFactory()方法的具體內容

    /**
     * Tell the subclass to refresh the internal bean factory.
     * @return the fresh BeanFactory instance
     * @see #refreshBeanFactory()
     * @see #getBeanFactory()
     */
    protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
        refreshBeanFactory();
        
 
return getBeanFactory();
    }

　　註釋上寫的：告訴子類重新整理內部的BeanFactory

    protected abstract void refreshBeanFactory() throws BeansException, IllegalStateException;

    public abstract ConfigurableListableBeanFactory getBeanFactory() throws IllegalStateException;

　　refreshBeanFactory()、getBeanFactory()方法是抽象方法，由子類實現，這裡的子類是AbstractRefreshableApplicationContext，它是AbstractApplicationContext的子類。（類圖可以參考：大綱）

二、關鍵在於refreshBeanFactory()方法

　　看看AbstractRefreshableApplicationContext的實現：

    @Override
    protected final void refreshBeanFactory() throws BeansException {
        if (hasBeanFactory()) {
            destroyBeans();
            closeBeanFactory();
        }
        try {
　　　　　　　　//（1）初始化BeanFactory
            DefaultListableBeanFactory beanFactory = createBeanFactory();
            beanFactory.setSerializationId(getId());
            customizeBeanFactory(beanFactory);
　　　　　　　　//（2）讀取BeanFefinition
            loadBeanDefinitions(beanFactory);
            synchronized (this.beanFactoryMonitor) {
                this.beanFactory = beanFactory;
            }
        }
        catch (IOException ex) {
            throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
        }
    }

(1)AbstractRefreshableApplicationContext.createBeanFactory()

　　建立DefaultListableBeanFactory物件，這個物件的類圖關係如下

　　不僅實現了BeanFactory，還實現了Registry相關介面，意味著和Bean的註冊有很大關係

(2) AbstractRefreshableApplicationContext.loadBeanDefinitions()

　　loadBeanDefinitions()是一個抽象方法，由AbstractXmlApplicationContext實現，類圖可參考：大綱

    @Override
    protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
        // （1）建立讀取Xml的物件，和BeanFactory是依賴關係
        XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);

        // （2）這些都是一些初始化操作
        beanDefinitionReader.setEnvironment(this.getEnvironment());
        beanDefinitionReader.setResourceLoader(this);
        beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));

        // （3）真正的初始化操作發生在最後一步loadBeanDefinitions
        initBeanDefinitionReader(beanDefinitionReader);
        loadBeanDefinitions(beanDefinitionReader);
    }

　　XmlBeanDefinitionReader初始化的beanFactory物件是BeanDefinitionRegistry介面的實現

    public XmlBeanDefinitionReader(BeanDefinitionRegistry registry) {
        super(registry);
    }

三、loadBeanDefinitions(beanDefinitionReader);通過Reader將XML Bean資訊讀取到BeanFactory中

　　BeanFactory和Reader之間的關係是依賴關係

    protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
        Resource[] configResources = getConfigResources();
        if (configResources != null) {
            reader.loadBeanDefinitions(configResources);
        }
        String[] configLocations = getConfigLocations();
        if (configLocations != null) {
            reader.loadBeanDefinitions(configLocations);
        }
    }

　　reader.loadBeanDefinitions(configLocations)方法中，將String型別的xml檔案地址轉為了Resource物件，下面就是通過流來讀取