第五章 spring-connet之AnnotationConfigUtils

前言

AnnotatedBeanDefinitionReader是AnnctionConfig相关上下文与AnnotationConfigUtils的桥梁。还有一个作用是解析class成为BeanDefinitionHolder，注册到容器里面。AnnotationConfigUtils是AnnctionConfig相关上下文最核心点，如果弄清楚AnnctionConfig相关上下文，那么就知道注解读取相关的机制。

registerAnnotationConfigProcessors方法

registerAnnotationConfigProcessors方法负责向容器里面注册相关的类。基本都给予某个体系。静态方法registerAnnotationConfigProcessors向容器里面注册了很多东西了。

1. AnnotationAwareOrderComparator注解排序类。对Order注解进行排序
2. ContextAnnotationAutowireCandidateResolver 处理Qualifier注解，这个点可能需要深入解读，spring设计得太复杂了。
3. ConfigurationClassPostProcessor 得到componentScan注解计算基本目录，并扫描对应目录。处理的注解还有PropertySources，Imports，Bean等等
4. AutowiredAnnotationBeanPostProcessor 基于spring bean的监视周期（BeanPostProcessor），扫描Autowired注解
5. RequiredAnnotationBeanPostProcessor 基于spring bean的监视周期（BeanPostProcessor），扫描Required注解，这个没啥用把
6. CommonAnnotationBeanPostProcessor 对javax.xml.ws.WebServiceRef注解与javax.ejb.EJB注解的兼容，真恶心
7. PersistenceAnnotationBeanPostProcessor 对jpa注解的兼容
8. EventListenerMethodProcessor 当所有bean（除了lazy）完成实例化之后，调用。找bean的方法室友有EventListener注解
9. DefaultEventListenerFactory 对EventListenerMethodProcessor的支持，目前不知晓有什么用

	public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
			BeanDefinitionRegistry registry, Objespringct 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<BeanDefinitionHolder>(4);

		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));
		}

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

总结

registerAnnotationConfigProcessors方法基本把主动性注解注册到容器里面了。如果在把扫面体系搞定，大部分注解都ok了，除了spring-boot的注解体系

processCommonDefinitionAnnotations方法

spring的annatated内容读取有三种方式反射，字节码，还有直接取。processCommonDefinitionAnnotations方法就是直接取spring明确定义的一些注解。这些注解都比较少时间，大家看下就行了。

static void processCommonDefinitionAnnotations(AnnotatedBeanDefinition abd, AnnotatedTypeMetadata metadata) {
		if (metadata.isAnnotated(Lazy.class.getName())) {
			abd.setLazyInit(attributesFor(metadata, Lazy.class).getBoolean("value"));
		}
		else if (abd.getMetadata() != metadata && abd.getMetadata().isAnnotated(Lazy.class.getName())) {
			abd.setLazyInit(attributesFor(abd.getMetadata(), Lazy.class).getBoolean("value"));
		}

		if (metadata.isAnnotated(Primary.class.getName())) {
			abd.setPrimary(true);
		}
		if (metadata.isAnnotated(DependsOn.class.getName())) {
			abd.setDependsOn(attributesFor(metadata, DependsOn.class).getStringArray("value"));
		}

		if (abd instanceof AbstractBeanDefinition) {
			AbstractBeanDefinition absBd = (AbstractBeanDefinition) abd;
			if (metadata.isAnnotated(Role.class.getName())) {
				absBd.setRole(attributesFor(metadata, Role.class).getNumber("value").intValue());
			}
			if (metadata.isAnnotated(Description.class.getName())) {
				absBd.setDescription(attributesFor(metadata, Description.class).getString("value"));
			}
		}
	}

随便说说

本来应该在9月19日完成，19日凌晨失眠，然后取了八卦岭吃东西。..............