21、spring注解学习（spring ioc 原理）——spring ioc 原理
一、总体流程
AnnotationConfigApplicationContext类的构造器方法
public AnnotationConfigApplicationContext(Class<?>... componentClasses) { this(); register(componentClasses); refresh(); }
AbstractApplicationContext类中的refresh()方法，即为spring容器的创建/刷数流程
@Override public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // 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); // 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(); // 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(); } } }
二、详细分析
1、Spring容器创建-BeanFactory预准备
BeanFactory的创建及预准备工作
Spring容器的refresh()【创建刷新】; 1、prepareRefresh()刷新前的预处理; 1）、initPropertySources()初始化一些属性设置;子类自定义个性化的属性设置方法； 2）、getEnvironment().validateRequiredProperties();检验属性的合法等 3）、earlyApplicationEvents= new LinkedHashSet<ApplicationEvent>();保存容器中的一些早期的事件； 2、obtainFreshBeanFactory();获取BeanFactory； 1）、refreshBeanFactory();刷新【创建】BeanFactory； 创建了一个this.beanFactory = new DefaultListableBeanFactory(); 设置序略化id； 2）、getBeanFactory();返回刚才GenericApplicationContext创建的BeanFactory对象； 3）、将创建的BeanFactory【DefaultListableBeanFactory】返回； 3、prepareBeanFactory(beanFactory);BeanFactory的预准备工作（BeanFactory进行一些设置）； 1）、设置BeanFactory的类加载器、支持表达式解析器... 2）、添加部分BeanPostProcessor【ApplicationContextAwareProcessor】 3）、设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx； 4）、注册可以解析的自动装配；我们能直接在任何组件中自动注入： BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext 5）、添加BeanPostProcessor【ApplicationListenerDetector】 6）、添加编译时的AspectJ； 7）、给BeanFactory中注册一些能用的组件； environment【ConfigurableEnvironment】、 systemProperties【Map<String, Object>】、 systemEnvironment【Map<String, Object>】 4、postProcessBeanFactory(beanFactory);BeanFactory准备工作完成后进行的后置处理工作； 1）、子类通过重写这个方法来在BeanFactory创建并预准备完成以后做进一步的设置 ======================以上是BeanFactory的创建及预准备工作==================================
对应的以下步骤：
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); // Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory);
2、Spring容器创建-执行BeanFactoryPostProcessor
执行BeanFactoryPostProcessor的方法；
5、invokeBeanFactoryPostProcessors(beanFactory);执行BeanFactoryPostProcessor的方法； BeanFactoryPostProcessor：BeanFactory的后置处理器。在BeanFactory标准初始化之后执行的； 两个接口：BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor 1）、执行BeanFactoryPostProcessor的方法； 先执行BeanDefinitionRegistryPostProcessor 1）、获取所有的BeanDefinitionRegistryPostProcessor； 2）、看先执行实现了PriorityOrdered优先级接口的BeanDefinitionRegistryPostProcessor、 postProcessor.postProcessBeanDefinitionRegistry(registry) 3）、在执行实现了Ordered顺序接口的BeanDefinitionRegistryPostProcessor； postProcessor.postProcessBeanDefinitionRegistry(registry) 4）、最后执行没有实现任何优先级或者是顺序接口的BeanDefinitionRegistryPostProcessors； postProcessor.postProcessBeanDefinitionRegistry(registry) 再执行BeanFactoryPostProcessor的方法 1）、获取所有的BeanFactoryPostProcessor 2）、看先执行实现了PriorityOrdered优先级接口的BeanFactoryPostProcessor、 postProcessor.postProcessBeanFactory() 3）、在执行实现了Ordered顺序接口的BeanFactoryPostProcessor； postProcessor.postProcessBeanFactory() 4）、最后执行没有实现任何优先级或者是顺序接口的BeanFactoryPostProcessor； postProcessor.postProcessBeanFactory()
对应执行的代码：
// Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory);
具体invokeBeanFactoryPostProcessors(beanFactory)方法为：<br>PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors()); // Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime // (e.g. through an @Bean method registered by ConfigurationClassPostProcessor) if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } }
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { // Invoke BeanDefinitionRegistryPostProcessors first, if any. Set<String> processedBeans = new HashSet<>(); if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>(); List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>(); for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) { if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) { BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor; registryProcessor.postProcessBeanDefinitionRegistry(registry); registryProcessors.add(registryProcessor); } else { regularPostProcessors.add(postProcessor); } } // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! // Separate between BeanDefinitionRegistryPostProcessors that implement // PriorityOrdered, Ordered, and the rest. List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>(); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered. 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); currentRegistryProcessors.clear(); // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered. 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); currentRegistryProcessors.clear(); // 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); currentRegistryProcessors.clear(); } // Now, invoke the postProcessBeanFactory callback of all processors handled so far. invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // Invoke factory processors registered with the context instance. invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); } // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); // Separate between BeanFactoryPostProcessors that implement PriorityOrdered, // Ordered, and the rest. List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>(); List<String> orderedPostProcessorNames = new ArrayList<>(); List<String> 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<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(); for (String postProcessorName : orderedPostProcessorNames) { orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } sortPostProcessors(orderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory); // Finally, invoke all other BeanFactoryPostProcessors. List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(); 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(); }
3、Spring容器创建-注册BeanPostProcessors
注册BeanPostProcessor(Bean的后置处理器)
6、registerBeanPostProcessors(beanFactory);注册BeanPostProcessor(Bean的后置处理器)【 intercept bean creation】 不同接口类型的BeanPostProcessor；在Bean创建前后的执行时机是不一样的 BeanPostProcessor、 DestructionAwareBeanPostProcessor、 InstantiationAwareBeanPostProcessor、 SmartInstantiationAwareBeanPostProcessor、 MergedBeanDefinitionPostProcessor【internalPostProcessors】、 1）、获取所有的 BeanPostProcessor;后置处理器都默认可以通过PriorityOrdered、Ordered接口来执行优先级 2）、先注册PriorityOrdered优先级接口的BeanPostProcessor； 把每一个BeanPostProcessor；添加到BeanFactory中 beanFactory.addBeanPostProcessor(postProcessor); 3）、再注册Ordered接口的 4）、最后注册没有实现任何优先级接口的 5）、最终注册MergedBeanDefinitionPostProcessor； 6）、注册一个ApplicationListenerDetector；来在Bean创建完成后检查是否是ApplicationListener，如果是 applicationContext.addApplicationListener((ApplicationListener<?>) bean);
对应执行的代码：
// Register bean processors that intercept bean creation. registerBeanPostProcessors(beanFactory);
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
public static void registerBeanPostProcessors( ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) { String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false); // Register BeanPostProcessorChecker that logs an info message when // a bean is created during BeanPostProcessor instantiation, i.e. when // a bean is not eligible for getting processed by all BeanPostProcessors. int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length; beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount)); // Separate between BeanPostProcessors that implement PriorityOrdered, // Ordered, and the rest. List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>(); List<BeanPostProcessor> internalPostProcessors = new ArrayList<>(); List<String> orderedPostProcessorNames = new ArrayList<>(); List<String> nonOrderedPostProcessorNames = new ArrayList<>(); for (String ppName : postProcessorNames) { if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class); priorityOrderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { orderedPostProcessorNames.add(ppName); } else { nonOrderedPostProcessorNames.add(ppName); } } // First, register the BeanPostProcessors that implement PriorityOrdered. sortPostProcessors(priorityOrderedPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors); // Next, register the BeanPostProcessors that implement Ordered. List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(); for (String ppName : orderedPostProcessorNames) { BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class); orderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } sortPostProcessors(orderedPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, orderedPostProcessors); // Now, register all regular BeanPostProcessors. List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(); for (String ppName : nonOrderedPostProcessorNames) { BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class); nonOrderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors); // Finally, re-register all internal BeanPostProcessors. sortPostProcessors(internalPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, internalPostProcessors); // Re-register post-processor for detecting inner beans as ApplicationListeners, // moving it to the end of the processor chain (for picking up proxies etc). beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext)); }
4、Spring容器创建-初始化MessageSource
初始化MessageSource组件
7、initMessageSource();初始化MessageSource组件（做国际化功能；消息绑定，消息解析）； 1）、获取BeanFactory 2）、看容器中是否有id为messageSource的，类型是MessageSource的组件 如果有赋值给messageSource，如果没有自己创建一个DelegatingMessageSource； MessageSource：取出国际化配置文件中的某个key的值；能按照区域信息获取； 3）、把创建好的MessageSource注册在容器中，以后获取国际化配置文件的值的时候，可以自动注入MessageSource； beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource); MessageSource.getMessage(String code, Object[] args, String defaultMessage, Locale locale);
对应执行的代码：
// Initialize message source for this context. initMessageSource(); 1 initMessageSource(); 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 /** * Initialize the MessageSource. * Use parent's if none defined in this context. */ protected void initMessageSource() { ConfigurableListableBeanFactory beanFactory = getBeanFactory(); if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) { this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class); // Make MessageSource aware of parent MessageSource. if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) { HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource; if (hms.getParentMessageSource() == null) { // Only set parent context as parent MessageSource if no parent MessageSource // registered already. hms.setParentMessageSource(getInternalParentMessageSource()); } } if (logger.isTraceEnabled()) { logger.trace("Using MessageSource [" + this.messageSource + "]"); } } else { // Use empty MessageSource to be able to accept getMessage calls. DelegatingMessageSource dms = new DelegatingMessageSource(); dms.setParentMessageSource(getInternalParentMessageSource()); this.messageSource = dms; beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource); if (logger.isTraceEnabled()) { logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]"); } } }
5、Spring容器创建-初始化事件派发器、监听器等
8、initApplicationEventMulticaster();初始化事件派发器； 1）、获取BeanFactory 2）、从BeanFactory中获取applicationEventMulticaster的ApplicationEventMulticaster； 3）、如果上一步没有配置；创建一个SimpleApplicationEventMulticaster 4）、将创建的ApplicationEventMulticaster添加到BeanFactory中，以后其他组件直接自动注入 9、onRefresh();留给子容器（子类） 1、子类重写这个方法，在容器刷新的时候可以自定义逻辑； 10、registerListeners();给容器中将所有项目里面的ApplicationListener注册进来； 1、从容器中拿到所有的ApplicationListener 2、将每个监听器添加到事件派发器中； getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName); 3、派发之前步骤产生的事件；
对应执行的代码：
// 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();
6、Spring容器创建-创建Bean准备
初始化所有剩下的单实例bean：
11、finishBeanFactoryInitialization(beanFactory);初始化所有剩下的单实例bean； 1、beanFactory.preInstantiateSingletons();初始化后剩下的单实例bean 1）、获取容器中的所有Bean，依次进行初始化和创建对象 2）、获取Bean的定义信息；RootBeanDefinition 3）、Bean不是抽象的，是单实例的，是懒加载； 1）、判断是否是FactoryBean；是否是实现FactoryBean接口的Bean； 2）、不是工厂Bean。利用getBean(beanName);创建对象 0、getBean(beanName)； ioc.getBean(); 1、doGetBean(name, null, null, false); 2、先获取缓存中保存的单实例Bean。如果能获取到说明这个Bean之前被创建过（所有创建过的单实例Bean都会被缓存起来） 从private final Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256);获取的 3、缓存中获取不到，开始Bean的创建对象流程； 4、标记当前bean已经被创建 5、获取Bean的定义信息； 6、【获取当前Bean依赖的其他Bean;如果有按照getBean()把依赖的Bean先创建出来；】 7、启动单实例Bean的创建流程； 1）、createBean(beanName, mbd, args); 2）、Object bean = resolveBeforeInstantiation(beanName, mbdToUse);让BeanPostProcessor先拦截返回代理对象； 【InstantiationAwareBeanPostProcessor】：提前执行； 先触发：postProcessBeforeInstantiation()； 如果有返回值：触发postProcessAfterInitialization()； 3）、如果前面的InstantiationAwareBeanPostProcessor没有返回代理对象；调用4） 4）、Object beanInstance = doCreateBean(beanName, mbdToUse, args);创建Bean 1）、【创建Bean实例】；createBeanInstance(beanName, mbd, args); 利用工厂方法或者对象的构造器创建出Bean实例； 2）、applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName); 调用MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition(mbd, beanType, beanName); 3）、【Bean属性赋值】populateBean(beanName, mbd, instanceWrapper); 赋值之前： 1）、拿到InstantiationAwareBeanPostProcessor后置处理器； postProcessAfterInstantiation()； 2）、拿到InstantiationAwareBeanPostProcessor后置处理器； postProcessPropertyValues()； =====赋值之前：=== 3）、应用Bean属性的值；为属性利用setter方法等进行赋值； applyPropertyValues(beanName, mbd, bw, pvs); 4）、【Bean初始化】initializeBean(beanName, exposedObject, mbd); 1）、【执行Aware接口方法】invokeAwareMethods(beanName, bean);执行xxxAware接口的方法 BeanNameAware\BeanClassLoaderAware\BeanFactoryAware 2）、【执行后置处理器初始化之前】applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); BeanPostProcessor.postProcessBeforeInitialization（）; 3）、【执行初始化方法】invokeInitMethods(beanName, wrappedBean, mbd); 1）、是否是InitializingBean接口的实现；执行接口规定的初始化； 2）、是否自定义初始化方法； 4）、【执行后置处理器初始化之后】applyBeanPostProcessorsAfterInitialization BeanPostProcessor.postProcessAfterInitialization()； 5）、注册Bean的销毁方法； 5）、将创建的Bean添加到缓存中singletonObjects； ioc容器就是这些Map；很多的Map里面保存了单实例Bean，环境信息。。。。；即这些所有的Map就构成了ioc容器。 所有Bean都利用getBean创建完成以后； 检查所有的Bean是否是SmartInitializingSingleton接口的；如果是；就执行afterSingletonsInstantiated()；
对应代码
// Instantiate all remaining (non-lazy-init) singletons. finishBeanFactoryInitialization(beanFactory);
AbstractApplicationContext类的finishBeanFactoryInitialization(beanFactory);
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(strVal -> 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(); }
DefaultListableBeanFactory类的preInstantiateSingletons()方法
@Override public void preInstantiateSingletons() throws BeansException { if (logger.isTraceEnabled()) { logger.trace("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<String> beanNames = new ArrayList<>(this.beanDefinitionNames); // 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)) { Object bean = getBean(FACTORY_BEAN_PREFIX + beanName); if (bean instanceof FactoryBean) { final FactoryBean<?> factory = (FactoryBean<?>) bean; boolean isEagerInit; if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) { isEagerInit = AccessController.doPrivileged((PrivilegedAction<Boolean>) ((SmartFactoryBean<?>) factory)::isEagerInit, getAccessControlContext()); } else { isEagerInit = (factory instanceof SmartFactoryBean && ((SmartFactoryBean<?>) factory).isEagerInit()); } if (isEagerInit) { getBean(beanName); } } } else { getBean(beanName); } } } // 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((PrivilegedAction<Object>) () -> { smartSingleton.afterSingletonsInstantiated(); return null; }, getAccessControlContext()); } else { smartSingleton.afterSingletonsInstantiated(); } } } }
AbstractBeanFactory类的getBean(String name)方法
@Override public Object getBean(String name) throws BeansException { return doGetBean(name, null, null, false); }
AbstractBeanFactory类的doGetBean(name, null, null, false);方法。创建bean的最终执行方法
@SuppressWarnings("unchecked")
protected <T> T doGetBean(final String name, @Nullable final Class<T> requiredType,
@Nullable final Object[] args, boolean typeCheckOnly) throws BeansException {
final String beanName = transformedBeanName(name);
Object bean;
// Eagerly check singleton cache for manually registered singletons.
Object sharedInstance = getSingleton(beanName);
if (sharedInstance != null && args == null) {
if (logger.isTraceEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.trace("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.trace("Returning cached instance of singleton bean '" + beanName + "'");
}
}
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
// Fail if we're already creating this bean instance:
// We're assumably within a circular reference.
if (isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// Check if bean definition exists in this factory.
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// Not found -> check parent.
String nameToLookup = originalBeanName(name);
if (parentBeanFactory instanceof AbstractBeanFactory) {
return ((AbstractBeanFactory) parentBeanFactory).doGetBean(
nameToLookup, requiredType, args, typeCheckOnly);
}
else if (args != null) {
// Delegation to parent with explicit args.
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else if (requiredType != null) {
// No args -> delegate to standard getBean method.
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
else {
return (T) parentBeanFactory.getBean(nameToLookup);
}
}
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
try {
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
// Guarantee initialization of beans that the current bean depends on.
String[] dependsOn = mbd.getDependsOn();
if (dependsOn != null) {
for (String dep : dependsOn) {
if (isDependent(beanName, dep)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
}
registerDependentBean(dep, beanName);
try {
getBean(dep);
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"'" + beanName + "' depends on missing bean '" + dep + "'", ex);
}
}
}
// Create bean instance.
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, () -> {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
// Explicitly remove instance from singleton cache: It might have been put there
// eagerly by the creation process, to allow for circular reference resolution.
// Also remove any beans that received a temporary reference to the bean.
destroySingleton(beanName);
throw ex;
}
});
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'");
}
try {
Object scopedInstance = scope.get(beanName, () -> {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
});
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; consider " +
"defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
catch (BeansException ex) {
cleanupAfterBeanCreationFailure(beanName);
throw ex;
}
}
// Check if required type matches the type of the actual bean instance.
if (requiredType != null && !requiredType.isInstance(bean)) {
try {
T convertedBean = getTypeConverter().convertIfNecessary(bean, requiredType);
if (convertedBean == null) {
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
return convertedBean;
}
catch (TypeMismatchException ex) {
if (logger.isTraceEnabled()) {
logger.trace("Failed to convert bean '" + name + "' to required type '" +
ClassUtils.getQualifiedName(requiredType) + "'", ex);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
}
return (T) bean;
}
7、Spring容器创建-容器创建完成
12、finishRefresh();完成BeanFactory的初始化创建工作；IOC容器就创建完成； 1）、initLifecycleProcessor();初始化和生命周期有关的后置处理器；LifecycleProcessor 默认从容器中找是否有lifecycleProcessor的组件【LifecycleProcessor】；如果没有new DefaultLifecycleProcessor(); 加入到容器； 写一个LifecycleProcessor的实现类，可以在BeanFactory void onRefresh(); void onClose(); 2）、 getLifecycleProcessor().onRefresh(); 拿到前面定义的生命周期处理器（BeanFactory）；回调onRefresh()； 3）、publishEvent(new ContextRefreshedEvent(this));发布容器刷新完成事件； 4）、liveBeansView.registerApplicationContext(this);
执行的代码
// Last step: publish corresponding event. finishRefresh();
finishRefresh();
protected void finishRefresh() { // Clear context-level resource caches (such as ASM metadata from scanning). clearResourceCaches(); // Initialize lifecycle processor for this context. initLifecycleProcessor(); // Propagate refresh to lifecycle processor first. getLifecycleProcessor().onRefresh(); // Publish the final event. publishEvent(new ContextRefreshedEvent(this)); // Participate in LiveBeansView MBean, if active. LiveBeansView.registerApplicationContext(this); }
8、Spring源码总结
======总结=========== 1）、Spring容器在启动的时候，先会保存所有注册进来的Bean的定义信息； 1）、xml注册bean；<bean> 2）、注解注册Bean；@Service、@Component、@Bean、xxx 2）、Spring容器会合适的时机创建这些Bean 1）、用到这个bean的时候；利用getBean创建bean；创建好以后保存在容器中； 2）、统一创建剩下所有的bean的时候；finishBeanFactoryInitialization()； 3）、后置处理器；BeanPostProcessor 1）、每一个bean创建完成，都会使用各种后置处理器进行处理；来增强bean的功能； AutowiredAnnotationBeanPostProcessor:处理自动注入 AnnotationAwareAspectJAutoProxyCreator:来做AOP功能； xxx.... 增强的功能注解： AsyncAnnotationBeanPostProcessor .... 4）、事件驱动模型； ApplicationListener；事件监听； ApplicationEventMulticaster；事件派发：
分类:
Spring
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