前言

本文接上文Spring 完整实现流程、完整源码分析，主要分析Spring执行refresh()方法前的一些操作！使用注解启动！

启动类

源码分析

1.切入AnnotationConfigApplicationContext
创建AnnotationConfigApplicationContext对象，代码如下

本文主要分析refresh()方法之前的流程，这里this调用如下代码

	public AnnotationConfigApplicationContext() {
		this.reader = new AnnotatedBeanDefinitionReader(this);
		this.scanner = new ClassPathBeanDefinitionScanner(this);
	}

因为AnnotationConfigApplicationContext继承了AbstractApplicationContext并且实现了BeanDefinitionRegistry接口那么在实例化AnnotationConfigApplicationContext时会调用继承的AbstractApplicationContext的构造方法

	public GenericApplicationContext() {
		this.beanFactory = new DefaultListableBeanFactory();
	}

这里是直接创建了DefaultListableBeanFactory对象DefaultListableBeanFactory有继承了AbstractAutowireCapableBeanFactory，而AbstractAutowireCapableBeanFactory有继承了AbstractBeanFactory，AbstractBeanFactory又继承了FactoryBeanRegistrySupport，同时FactoryBeanRegistrySupport继承了DefaultSingletonBeanRegistry，DefaultSingletonBeanRegistry的话实际上就是Spring的容器，容器如下

这三个实际上也就是我们常说的Spring的三级缓存，其中我们获取容器中的Bean就是从singletonObjects中获取到的，关于这三级缓存我这里占时不说，后期有空了把这块内容补充进来 @@@@@@@@@
那么看到这里我们就知道Spring容器创建的时候其实就是在这里开始创建的，也就是new DefaultListableBeanFactory();方法开始创建！这里创建好DefaultListableBeanFactory后赋值给了beanFactory

这里特意标注一下这个赋值给GenericApplicationContext的beanFactory流程，因为后面会获取这个beanFactory！完成这个操作后开始执行构造方法AnnotationConfigApplicationContext()中的两行代码

创建new AnnotatedBeanDefinitionReader(this)
这个对象其实就是读取注解标注Bean的描述信息的！

AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);

这行代码是切入到注解配置工具上去切入方法

	public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
		registerAnnotationConfigProcessors(registry, null);
	}

调用registerAnnotationConfigProcessors方法！

public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
			BeanDefinitionRegistry registry, @Nullable Object source) {

		DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
		if (beanFactory != null) {
			if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
				beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
			}
			if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
				beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
			}
		}

		Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);

		if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		// Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
		if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		// Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor.
		if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition();
			try {
				def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
						AnnotationConfigUtils.class.getClassLoader()));
			}
			catch (ClassNotFoundException ex) {
				throw new IllegalStateException(
						"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
			}
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
		}

		if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
		}

		return beanDefs;
	}

这个方法会返回一些处理器，如下！

1. ConfigurationClassPostProcessor
2. AutowiredAnnotationBeanPostProcessor
3. EventListenerMethodProcessor
4. DefaultEventListenerFactory

关于这些处理器后期会单独拎出来分析@@@@@@@
在返回这些处理器之前还会将这些处理器加入到DefaultListableBeanFactory的beanDefinitionNames中进行存储，那么到这里new AnnotatedBeanDefinitionReader(this)流程就走完了，现在开始创建ClassPathBeanDefinitionScanner