1、spring的依赖查找和依赖注入

依赖查找 DL Dependency Lookup 依赖查找是一种主动的行为，来解决对象的依赖问题，其更加直观可读，但是代码侵入性较高，较高依赖 API接口

比如使用 BeanFactory.getBean() 方法实时查找就是一种依赖查找的方式，或者通过 FactoryObject 函数式接口进行延迟查找 （注意这里和懒加载是两回事）

依赖注入 DI Dependency Injection 依赖注入是一种被动的注入行为，来解决对象的依赖问，其代码入侵性较小，可以较低或者不依赖于 API 接口，但是可读性相对较差

如我们说的 Spring 就是依赖注入的方式，体现于 @Autowired 注解、@Recourse 注解等

依赖注入的三种方式： 接口注入、构造器注入、setter 注入

2、springcontext的生命周期

1:refresh

2:start

3:stop

4:close

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();
		}
	}
}
    

总体的思路如下：

1:准备环境 prepareRefresh():

2:获取BeanFactory obtainFreshBeanFactory:ClassPathXmlApplicationContext在refreshBeanFactory的时候加载了configlocation路径上beanDefinition,

3:准备BeanFactory prepareBeanFactory,准备beanFactory,注册比较特殊的几个Bean,比如ClassLoader,PropertyEditorRegisrtrar,Environment LoadTimeWeaver,忽略掉一些不必要的接口实现

4:留给子类扩展BeanFactory：postProcessBeanFactory() 模版方法准备好了BeanFactory,但是留给了子类的拓展接口

5:执行BeanFactoryPostProcessor：invokeBeanFactoryPostProcessors();调用BeanFactoryBeanPostProcessor的实现，来处理BeanFactory，特别的是AnnotationConfigApplicationContext在这个步骤CommonConfigPostProcessor

6:初始化消息源:initMessageSource(),我们在i18章节讲到过

7:初始化事件广播器：initApplicationEventMutilcaster()

8:留给子类扩展 context: onRefresh();在 留给context的子类一个扩展口，来实例化一些特殊作用的bean，

9:注册事件监听器 ：registerListener()

10:实例化所有非延迟加载的bean: finishBeanFactoryInitialization(beanFactory);这些bean都是在obtainBeanFactory加载的，在InvokeBeanFactoryPostProcessor时处理的@ComponentScan组建，@Configuration @Import @Bean等新加入的beanDefinition

11:清除上面扫描反射加载等操作的缓存:

12:lifeCycle组建启动

13:广播事件 refreshEvent ,

14:注册MBean

15:重制缓存:finanlly{}模块