Spring IOC refresh()方法——功能扩展

功能扩展
进入函数prepareBeanFactory之前，spring已经完成了对配置的解析，而ApplicationContext在功能上的扩展也由此展开。

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
    // Tell the internal bean factory to use the context's class loader etc.
    // 设置beanFactory的classLoader为当前context的classLoader
    beanFactory.setBeanClassLoader(getClassLoader());
    // 设置beanFactory的表达式语言处理器，Spring3增加了表达式语言的支持
    beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver());
    // 为beanFactory增加一个默认的PropertyEditor，这个主要是对bean的属性等设置管理的一个工具
    beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

    // Configure the bean factory with context callbacks.
    // 增加BeanPostProcessor
    beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
    // 设置了几个忽略自动装配的接口
    beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
    beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
    beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
    beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
    beanFactory.ignoreDependencyInterface(EnvironmentAware.class);

    // BeanFactory interface not registered as resolvable type in a plain factory.
    // MessageSource registered (and found for autowiring) as a bean.
    // 设置了几个自动装配的特殊规则
    beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
    beanFactory.registerResolvableDependency(ResourceLoader.class, this);
    beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
    beanFactory.registerResolvableDependency(ApplicationContext.class, this);

    // Detect a LoadTimeWeaver and prepare for weaving, if found.
    // 增加对AspectJ的支持
    if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
        beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
        // Set a temporary ClassLoader for type matching.
        beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
    }

    // Register default environment beans.
    // 增加默认的系统环境bean
    if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
        beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
    }
    if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
        beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
    }
    if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
        beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
    }
}

上面方法主要进行了以下方面的扩展：

增加对SPEL语言的支持
增加对属性编辑器的支持
增加对一些内置类，比如EnvironmentAware、MessageSourceAware的信息注入。
设置了依赖功能可忽略的接口
注册一些固定依赖的属性
增加AspectJ的支持
将相关环境变量及属性注册以单例模式注册