spring ApplicationContext

文章目录

ApplicationContext 这个是带有上下文的容器

启动过程

以ClassPathXmlApplicationContext为例

public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			StartupStep contextRefresh = this.applicationStartup.start("spring.context.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);

			try {
				// Allows post-processing of the bean factory in context subclasses.
				postProcessBeanFactory(beanFactory);

				StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");
				// Invoke factory processors registered as beans in the context.
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation.
				registerBeanPostProcessors(beanFactory);
				beanPostProcess.end();

				// 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();
				contextRefresh.end();
			}
		}

1.prepareRefresh

在应用刷新前的一些准备工作

2.准备BeanFactory

生成beanfactory
DefaultListableBeanFactory beanFactory = createBeanFactory();

3.设置Beanfactory

prepareBeanFactory(beanFactory);
比如

		// Configure the bean factory with context callbacks.
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		beanFactory.ignoreDependencyInterface(EnvironmentAware.class);

4.注册BeanFactoryPostProcessor

就是这个接口的实现
BeanFactoryPostProcessor

	postProcessBeanFactory(beanFactory);

	StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");
				// Invoke factory processors registered as beans in the context.
   invokeBeanFactoryPostProcessors(beanFactory);

5.注册BeanPostProcessor

	// Register bean processors that intercept bean creation.
	registerBeanPostProcessors(beanFactory);
	beanPostProcess.end();

6.国际化处理

initMessageSource();

7.事件广播器

初始化事件广播器

initApplicationEventMulticaster();

8.注册listener

就是实现ApplicationListener这个接口的bean
监听事件得到通知

	registerListeners();

9.实现化bean

finishBeanFactoryInitialization

10.结束

finishRefresh()

protected void finishRefresh() {
		// Publish the final event.
		发布这个事件，可以在前面实现监听这个事件
		publishEvent(new ContextRefreshedEvent(this));
	}