Spring源码------IOC容器初始化过程

前言

IOC容器的初始化过程,我这边分为两大步

1.容器的初始化

AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(MyConfig.class);

2.Bean的创建

Food food = annotationConfigApplicationContext.getBean("food", Food.class);

1.容器的初始化

1.1初始化DefaultListableBeanFactory

AnnotationConfigApplicationContext继承GenericApplicationContext,所以在初始化AnnotationConfigApplicationContext的时候,会先调用父类GenericApplicationContext的构造函数,而 DefaultListableBeanFactory实现了BeanDefinitionRegistry,所以最终AnnotationConfigApplicationContext既是一个BeanFactory,也是一个BeanDefinitionRegistry


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

1.2初始化reader

this.reader = new AnnotatedBeanDefinitionReader(this);

该方法最主要的作用就是注册内置的五个BeanDefinition到BeanDefinitionMap中,重点关注前两个

ConfigurationClassPostProcessor[实现BeanDefinitionRegistryPostProcessor]

AutowiredAnnotationBeanPostProcessor[实现BeanPostProcessor]

CommonAnnotationBeanPostProcessor[实现BeanPostProcessor]

EventListenerMethodProcessor[实现BeanFactoryPostProcessor]

DefaultEventListenerFactory


public static Set 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 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;
	}

1.3初始化scanner

该scanner只有显式调用才会用到,不重要

annotationConfigApplicationContext.scan("com.lyf.study");

1.4注册传入的配置类MyConfig


public void register(Class... componentClasses) {
		for (Class componentClass : componentClasses) {
			registerBean(componentClass);
		}
	}

最终会到AnnotatedBeanDefinitionReader中的doRegisterBean方法中

关键步骤如下:

1.4.1解析@Conditional注解,判断配置类是否满足加载条件,不满足则直接跳过


if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
	return;
}

1.4.2将配置类注册到BeanDefinitionMap中

BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);

1.5执行refresh的invokeBeanFactoryPostProcessor

1.5.1执行手动添加的BeanDefinitionRegistryPostProcessor

若手动注册为BeanDefinitionRegistryPostProcessor,则先执行其postProcessBeanDefinitionRegistry方法

注:BeanFactoryPostProcessor是BeanDefinitionRegistryPostProcessor的父类

BeanFactoryPostProcessor

有postProcessBeanFactory方法,主要用于修改BeanDefinitionMap中的BeanDefinition

BeanDefinitionRegistryPostProcessor

有postProcessBeanDefinitionRegistry方法,主要用于添加BeanDefinition到BeanDefinitionMap中


//beanFactoryPostProcessors中的所有postProcessor都是显式调用annotationConfigApplicationContext.addBeanFactoryPostProcessor(null);来的
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					registryProcessors.add(registryProcessor);
				}
				else {
					regularPostProcessors.add(postProcessor);
				}
			}

1.5.2 执行实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor(关键)


			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
			currentRegistryProcessors.clear();

这里默认情况下只会获取到reader中注册的5个内置的BeanFactoryPostProcessor中的ConfigurationClassPostProcessor,然后执行ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry方法

ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry非常的关键,它主要做了一下几件事:

(1)从beanFactory中获取所有已经注册到BeanDefinitionMap中的BeanDefinitionNames

(2)给使用了@Configuration注解的BeanDefinition打上full的标识[后续会使用cglib增强],给使用了@Order注解的BeanDefinition打上优先等级

(3)将符合(2)的所有BeanDefinition放入configCandidates列表中

(4)对configCandidates列表中的BeanDefinition,依据order属性值排序,值越小,优先级越高

(5)构建ConfigurationClassParser,解析每一个使用@Configuration的类,内部会对@Component、@PropertySource、@ComponentScan、@Import、@ImportResource、@Bean注解做处理

(6)将解析出来的对象转成BeanDefintion注册到BeanDefinitionMap中

1.5.3 执行实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor


postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
			currentRegistryProcessors.clear();

1.5.4执行剩下的BeanDefinitionRegistryPostProcessor


// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
			boolean reiterate = true;
			while (reiterate) {
				reiterate = false;
				postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
				for (String ppName : postProcessorNames) {
					if (!processedBeans.contains(ppName)) {
						currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
						processedBeans.add(ppName);
						reiterate = true;
					}
				}
				sortPostProcessors(currentRegistryProcessors, beanFactory);
				registryProcessors.addAll(currentRegistryProcessors);
				invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
				currentRegistryProcessors.clear();
			}

1.5.5执行所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory


			// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);

1.5.6执行所有BeanFactoryPostProcessor的postProcessBeanFactory


String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
 
		// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		List priorityOrderedPostProcessors = new ArrayList<>();
		List orderedPostProcessorNames = new ArrayList<>();
		List nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {
			if (processedBeans.contains(ppName)) {
				// skip - already processed in first phase above
			}
			else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
			}
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}
 
		// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
 
		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		List orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
 
		// Finally, invoke all other BeanFactoryPostProcessors.
		List nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
		for (String postProcessorName : nonOrderedPostProcessorNames) {
			nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
 
		// Clear cached merged bean definitions since the post-processors might have
		// modified the original metadata, e.g. replacing placeholders in values...
		beanFactory.clearMetadataCache();

1.6执行refresh的registerBeanPostProcessors方法

依据内置的AutowiredAnnotationBeanPostProcessor和CommonAnnotationBeanPostProcessor对应的BeanDefinition,生成相对应的Bean,并添加到容器中

BeanDefinitionRegistryPostProcessor

最先执行,主要用于添加BeanDefinition

BeanFactoryPostProcessor

次要执行,主要用于修改BeanDefinition

BeanPostProcessor

最后执行,在Bean初始化前会调用postProcessBeforeInitialization,在Bean初始化之后会调用postProcessAfterInitialization

至此,容器大致的初始化过程结束.

2.Bean的创建

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原文地址：https://blog.csdn.net/chengtanyong4777/article/details/126473425

Spring源码------IOC容器初始化过程

前言

​​​​​​​

1.容器的初始化

1.1初始化DefaultListableBeanFactory

1.2初始化reader

1.3初始化scanner

1.4注册传入的配置类MyConfig

1.4.1解析@Conditional注解,判断配置类是否满足加载条件,不满足则直接跳过

1.4.2将配置类注册到BeanDefinitionMap中

1.5执行refresh的invokeBeanFactoryPostProcessor

1.5.1执行手动添加的BeanDefinitionRegistryPostProcessor

1.5.2 执行实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor(关键)

1.5.3 执行实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor

1.5.4执行剩下的BeanDefinitionRegistryPostProcessor

1.5.5执行所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory

1.5.6执行所有BeanFactoryPostProcessor的postProcessBeanFactory

1.6执行refresh的registerBeanPostProcessors方法

2.Bean的创建