spring ioc获取bean源码查看

         ApplicationContext a=new ClassPathXmlApplicationContext("bean.xml");
        Object aa = a.getBean("aa");
        System.out.println(aa);

进入查看源码

三个参数分别对应下面三个this代表调用自己的带参构造函数

端点对refresh放行后控制台会打印出数据。

public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			prepareRefresh();//预准备刷新过程，控制台会有日志
//十月 01, 2019 8:49:03 下午 //org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
//信息: Refreshing //org.springframework.context.support.ClassPathXmlApplicationContext@56ef9176: startup //date [Tue Oct 01 20:49:03 CST 2019]; root of context hierarchy

			// Tell the subclass to refresh the internal bean factory.
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();//spring解析XML文件，这步骤过去了debug的栏目里有数据了

			// 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();//国际化功能

				// 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);
                //以上都是创建步骤，最后的finish创建了bean

				// 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();
			}
		}
	}

ConfigurableListableBeanFactory是factory的子类，applicationContext也是factory的子类

finishBeanFactoryInitialization(beanFactory);进入此方法

是在抽象类中AbstactApplicationContext中

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
		// Initialize conversion service for this context.
		if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
				beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
			beanFactory.setConversionService(
					beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
		}

		// Register a default embedded value resolver if no bean post-processor
		// (such as a PropertyPlaceholderConfigurer bean) registered any before:
		// at this point, primarily for resolution in annotation attribute values.
		if (!beanFactory.hasEmbeddedValueResolver()) {
			beanFactory.addEmbeddedValueResolver(new StringValueResolver() {
				@Override
				public String resolveStringValue(String strVal) {
					return getEnvironment().resolvePlaceholders(strVal);
				}
			});
		}

		// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
		String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
		for (String weaverAwareName : weaverAwareNames) {
			getBean(weaverAwareName);
		}

		// Stop using the temporary ClassLoader for type matching.
		beanFactory.setTempClassLoader(null);

		// Allow for caching all bean definition metadata, not expecting further changes.
		beanFactory.freezeConfiguration();

		// Instantiate all remaining (non-lazy-init) singletons.
		beanFactory.preInstantiateSingletons();//初始化单实例bean

以上有些方法见名知意就不解释了，继续跟踪下来到DefaultListableBeanFactory

@Override
	public void preInstantiateSingletons() throws BeansException {
		if (this.logger.isDebugEnabled()) {
			this.logger.debug("Pre-instantiating singletons in " + this);
		}

		// Iterate over a copy to allow for init methods which in turn register new bean definitions.
		// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
		List beanNames = new ArrayList(this.beanDefinitionNames);
//以上就是获取bean名字

		// Trigger initialization of all non-lazy singleton beans...
		for (String beanName : beanNames) {
			RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
			if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
				if (isFactoryBean(beanName)) {//工厂bean建造对象
					final FactoryBean factory = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName);
					boolean isEagerInit;
					if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
						isEagerInit = AccessController.doPrivileged(new PrivilegedAction() {
							@Override
							public Boolean run() {
								return ((SmartFactoryBean) factory).isEagerInit();
							}
						}, getAccessControlContext());
					}
					else {
						isEagerInit = (factory instanceof SmartFactoryBean &&
								((SmartFactoryBean) factory).isEagerInit());
					}
					if (isEagerInit) {
						getBean(beanName);
					}
				}
				else {
					getBean(beanName);//创造对象
				}
			}
		}

		// Trigger post-initialization callback for all applicable beans...
		for (String beanName : beanNames) {
			Object singletonInstance = getSingleton(beanName);
			if (singletonInstance instanceof SmartInitializingSingleton) {
				final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
				if (System.getSecurityManager() != null) {
					AccessController.doPrivileged(new PrivilegedAction