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();
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BeanFactory
ConfigurableListableBeanFactory 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BeanPostProcessor
registerBeanPostProcessors(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();
}
}
}
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
文章来源：https://www.toymoban.com/news/detail-648402.html
beanFactory.preInstantiateSingletons()：提前加载单例对象文章来源地址https://www.toymoban.com/news/detail-648402.html
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