这是我参与8月更文挑战的第6天，活动详情查看：8月更文挑战
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：
//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：
//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：
// 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：
// 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，
- 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
- 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；
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。
