Mr. Cappuccino的第63杯咖啡——Spring之AnnotationConfigApplicationContext源码分析

源码分析

以上一篇文章《Spring之Bean的生命周期》的代码进行源码分析

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringConfig02.class);
LifeCycleBean lifeCycleBean = applicationContext.getBean("lifeCycleBean", LifeCycleBean.class);
System.out.println("-----------------------------------");
System.out.println("LifeCycleBean " + lifeCycleBean);
System.out.println("-----------------------------------");
applicationContext.close();

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new AnnotationConfigApplicationContext(SpringConfig02.class)

AnnotationConfigApplicationContext.java

AbstractApplicationContext.java

@Override
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {// Prepare this context for refreshing.// 容器刷新前的准备工作，例如对系统属性、环境变量进行准备及验证prepareRefresh();// Tell the subclass to refresh the internal bean factory.// 初始化BeanFactoryConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// Prepare the bean factory for use in this context.// 对BeanFactory进行属性填充及功能填充，例如添加某些BeanPostProcessor以实现某些功能（ApplicationContextAwareProcessor）prepareBeanFactory(beanFactory);try {// Allows post-processing of the bean factory in context subclasses.// 空方法，用于子类实现扩展功能postProcessBeanFactory(beanFactory);// Invoke factory processors registered as beans in the context.// 执行BeanFactoryPostProcessor，例如ConfigurationClassPostProcessor、EventListenerMethodProcessor以及某些自定义的BeanFactoryPostProcessor// ConfigurationClassPostProcessor用于处理配置类，会将配置类中需要注册的Bean对象的元数据解析并存入beanDefinitionMap集合中invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.// 注册BeanPostProcessor，例如AutowiredAnnotationBeanPostProcessor、CommonAnnotationBeanPostProcessor以及某些自定义的BeanPostProcessorregisterBeanPostProcessors(beanFactory);// Initialize message source for this context.// 初始化消息资源，国际化处理initMessageSource();// Initialize event multicaster for this context.// 初始化消息多播器initApplicationEventMulticaster();// Initialize other special beans in specific context subclasses.// 空方法，用于子类实现扩展功能onRefresh();// Check for listener beans and register them.// 注册所有的ApplicationListener到消息多播器registerListeners();// Instantiate all remaining (non-lazy-init) singletons.// 实例化、初始化剩下的非懒加载的单例对象finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.// 完成刷新动作，启动LifecycleProcessor，发布ContextRefreshedEvent事件finishRefresh();}catch (BeansException ex) {if (logger.isWarnEnabled()) {logger.warn("Exception encountered during context initialization - " +"cancelling refresh attempt: " + ex);}// Destroy already created singletons to avoid dangling resources.// 销毁已创建的单例对象destroyBeans();// Reset 'active' flag.cancelRefresh(ex);// Propagate exception to caller.throw ex;}finally {// Reset common introspection caches in Spring's core, since we// might not ever need metadata for singleton beans anymore...resetCommonCaches();}}
}

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BeanFactory中两个重要的对象

DefaultListableBeanFactory.java

/** Map of bean definition objects, keyed by bean name. */
private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<>(256);

DefaultSingletonBeanRegistry.java

/** Cache of singleton objects: bean name to bean instance. */
private final Map<String, Object> singletonObjects = new ConcurrentHashMap<>(256);

Debug源码分析

register(componentClasses)：注册指定的配置类SpringConfig02到beanDefinitionMap集合中

invokeBeanFactoryPostProcessors(beanFactory)：创建BeanFactoryPostProcessor接口相关实现类的实例对象并存入singletonObjects集合中；执行BeanFactoryPostProcessor接口相关实现类的方法，通过ConfigurationClassPostProcessor处理配置类中需要注册的bean对象，并将bean对象注册到beanDefinitionMap集合中。

registerBeanPostProcessors(beanFactory)：注册BeanPostProcessor接口相关实现类，创建BeanPostProcessor接口相关实现类的实例对象并存入singletonObjects集合中

finishBeanFactoryInitialization(beanFactory)：实例化、初始化剩下的非懒加载的单例对象并存入singletonObjects集合中

beanFactory.preInstantiateSingletons()：提前加载单例对象

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