Spring是一个非常活跃的开源框架;它是一个基于Core来架构多层JavaEE系统的框架,它的主要目的是简化企业开发。Spring以一种非侵入式的方式来管理你的代码,Spring提倡“最少侵入,这也意味着你可以适当的时候安装或卸载Spring。
1、BeanFactory
2、ApplicationContext
3、Bean创建过程
4、容器扩展
5、感知接口 *Aware
6、广播与监听
7、资源
8、运行环境抽象
BeanFactory类图
BeanFactory 源码脉络
AbstractApplicationContext .refresh() 源码脉络
AbstractApplicationContext .refresh() 方法
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 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);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
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.
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();
}
}
}
主要用于获取一个新的BeanFactory,如果BeanFactory已存在,则将其销毁并重建,默认重建的BeanFactory为AbstractRefreshableApplicationContext;此外此方法委托其子类从XML中或基于注解的类中加载BeanDefinition
配置BeanFactory使其具有一个上下文的标准特征,如上下文的类加载器、后处理程序(post-processors,如设置如总感知接口)
在应用上下文内部的BeanFactory初始化结束后对其进行修改,在所有的BeanDefinition已被加载但还没有实例化bean, 此刻可以注册一些特殊的BeanPostFactory,如web应用会注册ServletContextAwareProcessor等
调用注册在上下文中的BeanFactoryPostProcessor,如果有顺序则按顺序调用,并且一定再单列对象实例化之前调用
实例化并注册BeanPostProcessor,如果有显式的顺序则按照顺序调用一定在所有bean实例化之前调用
初始化MessageSource,如果当前上下文没有定义则使用其父类的,如果BeanFactory中不能找到名称为messageSource中的bean, 则默认使用DelegatingMessageSource
初始化ApplicationEventMulticaster,如果上下文没有定义则默认使用SimpleApplicationEventMulticaster,此类主要用于广播ApplicationEvent
在一些特定的上下文子类中初始化特定的bean,如在Webapp的上下文中初始化主题资源
添加实现了ApplicationListener的bean作为监听器,它不影响非bean的监听器;还会使用多播器发布早期的ApplicationEvent
实例化所有非延迟加载的单例,完成BeanFactory的初始化工作
完成上下文的刷新工作,调用LifecycleProcessor的onFresh()及发布的ContextRefreshEvent事件
重置Spring公共的缓存,如:ReflectionUtils、ResolvableType、CachedIntrospectionResults的缓存CachedIntrospectionResults的缓存