SpringBoot bean解析之refresh方法（二）

继续看AbstractApplicationContext类中的prepareBeanFactory(beanFactory)方法：

	/**
	 * Configure the factory's standard context characteristics,
	 * such as the context's ClassLoader and post-processors.
	 * @param beanFactory the BeanFactory to configure
	 */
	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		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.
		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.
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

		// Detect a LoadTimeWeaver and prepare for weaving, if found.
		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.
		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());
		}
	}

        从注释我们可以了解到，它的作用是配置工厂的标准上下文特征，如类加载器和后处理器。

        ignoreDependencyInterface方法用来添加忽略的自动装配接口；

        在之前添加的后处理器ApplicationContextAwareProcessor，用来处理ignoreDependencyInterface方法忽略的接口；

        registerResolvableDependency用来向beanFactory添加一些解析依赖。ResourceLoader、ApplicationEventPublisher、ApplicationContext都指向了自身。

        添加后置处理器ApplicationListenerDetector

        如果beanFactory包含bean：LOAD_TIME_WEAVER_BEAN_NAME（即"loadTimeWeaver"），就添加一个postprocessor和一个临时的classLoader。（这里不包含）

        如果beanFactory不包含bean：ENVIRONMENT_BEAN_NAME（即"environment"），就注册一个ENVIRONMENTbean；

          同样地：注册SystemProperties和SystemEnvironment的bean。

          接下来，进入postProcessBeanFactory方法中：

	@Override
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		super.postProcessBeanFactory(beanFactory);
		if (this.basePackages != null && this.basePackages.length > 0) {
			this.scanner.scan(this.basePackages);
		}
		if (!this.annotatedClasses.isEmpty()) {
			this.reader.register(ClassUtils.toClassArray(this.annotatedClasses));
		}
	}

        首先调用父类的方法：

	/**
	 * Register ServletContextAwareProcessor.
	 * @see ServletContextAwareProcessor
	 */
	@Override
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		beanFactory.addBeanPostProcessor(new WebApplicationContextServletContextAwareProcessor(this));
		beanFactory.ignoreDependencyInterface(ServletContextAware.class);
		registerWebApplicationScopes();
	}

        添加了一个后置处理器和忽略的自动装配接口；最后的registerWebApplicationScopes代码如下：

	private void registerWebApplicationScopes() {
		ExistingWebApplicationScopes existingScopes = new ExistingWebApplicationScopes(getBeanFactory());
		WebApplicationContextUtils.registerWebApplicationScopes(getBeanFactory());
		existingScopes.restore();
	}

        用来添加web特有的作用域，例如REQUEST、SESSION。

        回到子类的postProcessBeanFactory方法，我们这里basePackages、annotatedClasses都是空的，所以会跳过下面的if。postProcessBeanFactory总体上是为了子类重写BeanFactory完成创建后做进一步设置。

        下面进入invokeBeanFactoryPostProcessors(beanFactory)中，此方法的目的是调用在上下文中注册为bean的工厂处理器。

	/**
	 * Instantiate and invoke all registered BeanFactoryPostProcessor beans,
	 * respecting explicit order if given.
	 * <p>Must be called before singleton instantiation.
	 */
	protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
		PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());

		// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
		// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
		if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
			beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
			beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
		}
	}

        getBeanFactoryPostProcessors方法返回beanFactoryPostProcessors，这是一个List结构，断点调试发现里面有3个处理器，都是通过初始化器和监听器来添加的。关于初始化器和监听器，可以通过本人的其他博文或其他文章详细了解。