Spring源码系列（三）：refresh()方法详解之prepareBeanFactory(beanFactory)方法

一、refresh()方法之prepareBeanFactory(beanFactory)方法

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

二、prepareBeanFactory(beanFactory)方法详解

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
        // Tell the internal bean factory to use the context's class loader etc.
        // 设置类加载器：存在则直接设置/不存在则新建一个默认类加载器
        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
        // 默认可以使用#{bean.xxx}的形式来调用相关属性值
        beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
        //设置属性注册解析器PropertyEditor
        beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

        // Configure the bean factory with context callbacks.
        // 将当前的ApplicationContext对象交给ApplicationContextAwareProcessor类来处理，从而在Aware接口实现类中的注入applicationContext
        // 通过ApplicationContextAwareProcessor#invokeAwareInterfaces进行aware接口信息回调
        beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
        //设置忽略自动装配的接口
        beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
        beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
        beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
        beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
        beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
        beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);

        // BeanFactory interface not registered as resolvable type in a plain factory.
        // MessageSource registered (and found for autowiring) as a bean.
        // 注册可以解析的自动装配
        beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
        beanFactory.registerResolvableDependency(ResourceLoader.class, this);
        beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
        beanFactory.registerResolvableDependency(ApplicationContext.class, this);

        // Register early post-processor for detecting inner beans as ApplicationListeners.
        //将当前applicationContext交给ApplicationListenerDetector类处理
        beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

        // Detect a LoadTimeWeaver and prepare for weaving, if found.
        // 如果当前BeanFactory包含loadTimeWeaver Bean，说明存在类加载期织入AspectJ，
        // 则把当前BeanFactory交给类加载期BeanPostProcessor实现类LoadTimeWeaverAwareProcessor来处理，
        // 从而实现类加载期织入AspectJ的目的.
        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.
        //注册当前容器环境environment组件Bean
        if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
            beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
        }
        // 注册系统配置systemProperties组件Bea
        if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
            beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
        }
        //注册系统环境systemEnvironment组件Bean
        if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
            beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
        }
    }

三、总结

prepareBeanFactory主要做的：

1. 设置beanFactory的classLoader为当前context的classLoader。
2. 设置beanFactory的表达式语言处理器。
3. 添加Aware回调接口的后处理器ApplicationContextAwareProcessor。
4. 设置需要忽略自动装配的接口。
5. 增加对AspectJ的支持。
6. 添加默认的系统环境bean。