spring源码(二)beanFactory预处理

图片

前言

上一篇已经介绍了spring容器初始化的大概流程,这次对其中的一些流程进行仔细分析。

正文

这次分析spring容器创建流程中的前几个流程:

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    //所在类及方法:AbstractApplicationContext.refresh()
            // 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);

prepareRefresh

方法上面的注释也写得很明白:为刷新准备上下文,进方法源码:

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    //所在类及方法:AbstractApplicationContext.prepareRefresh()
    protected void prepareRefresh() {
		this.startupDate = System.currentTimeMillis(); // 记录启动时间
		this.closed.set(false); // 设置容器关闭状态为false
		this.active.set(true); // 设置容器活跃状态为true
		if (logger.isDebugEnabled()) {
			if (logger.isTraceEnabled()) {
				logger.trace("Refreshing " + this);
			}
			else {
				logger.debug("Refreshing " + getDisplayName());
			}
		}
		// Initialize any placeholder property sources in the context environment.
		initPropertySources();// 初始化PropertySources

		// Validate that all properties marked as required are resolvable:
		// see ConfigurablePropertyResolver#setRequiredProperties
		getEnvironment().validateRequiredProperties(); // 校验获得的Property

		// Store pre-refresh ApplicationListeners... 
        // 初始化存储ApplicationListeners的
		if (this.earlyApplicationListeners == null) {
			this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
		}
		else {
			// Reset local application listeners to pre-refresh state.
			this.applicationListeners.clear();
			this.applicationListeners.addAll(this.earlyApplicationListeners);
		}

		// Allow for the collection of early ApplicationEvents,
		// to be published once the multicaster is available...
        // 初始化存储earlyApplicationEvents
		this.earlyApplicationEvents = new LinkedHashSet<>();
	}

这个方法相对来说做的事情是比较简单的,都是前期的一些准备, 就是初始化this.startupDate ,this.closed.set(false),this.active.set(true),applicationListeners,earlyApplicationListeners,earlyApplicationEvents这些属性。

注意点就是其中的initPropertySources这个方法,该方法默认是没有什么动作的,不过在spring-web包下有三个类实现了该方法。

obtainFreshBeanFactory方法

这个方法的源码也比较简单:

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    // 所在类及方法:AbstractApplicationContext.obtainFreshBeanFactory
    protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
        // 刷新BeanFactory
		refreshBeanFactory();
        // 返回
		return getBeanFactory();
	}

在AbstractApplicationContext类中,上面的两个方法都是接口,从上篇文章中,使用的是AnnotationConfigApplicationContext,从类继承图可以知道, GenericApplicationContext类对上述两个方法有实现,直接定位至GenericApplicationContext类:

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    // 所在类:GenericApplicationContext
    @Override
	protected final void refreshBeanFactory() throws IllegalStateException {
		if (!this.refreshed.compareAndSet(false, true)) { //cas修改refreshed状态
			throw new IllegalStateException(
					"GenericApplicationContext does not support multiple refresh attempts: just call 'refresh' once");
		}
		this.beanFactory.setSerializationId(getId());
	}

    @Override
	public final ConfigurableListableBeanFactory getBeanFactory() {
		return this.beanFactory;
	}

上述两个方法都是比较简单的,

  1. refreshBeanFactory方法使用cas修改refreshed值,将其修改为true,最后再给beanFactory的序列化ID赋值
  2. getBeanFactory更简单,beanFactory的属性在构造方法中已经初始化为DefaultListableBeanFactory,所以这里返回的是DefaultListableBeanFactory;

还有,debug该方法,beanFactory中的bean信息只有几个,并不是将所有的bean信息都注册了,所以,beanFactory的自动发现(扫描bean信息)不是在这里发生了。

prepareBeanFactory方法

准备beanFactory,其实就是对beanFactory中的一些属性进行赋值;

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    protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());// 设置类加载器
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));// 设置表达式解析器
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));// 设置property

		// Configure the bean factory with context callbacks.
        // 配置beanFactory上下文的回调处理
		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.
        // 添加自动发现及注入的支持
		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.
        // 监听器组件
		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.
        // 注册默认环境信息
		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());
		}
	}

这个方法就比较复杂了,对beanFactory很多属性进行了设置。

最后

好了,beanFactory的预处理就差不多完成了,下面就是后置处理了。

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