一、Spring容器的refresh()

spring version:4.3.12 ，尚硅谷Spring注解驅動開發—源碼部分

//refresh():543, AbstractApplicationContext (org.springframework.context.support) public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { //1 刷新前的預處理 prepareRefresh(); //2 獲取BeanFactory；剛創建的默認DefaultListableBeanFactory ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); //3 BeanFactory的預準備工作（BeanFactory進行一些設置） prepareBeanFactory(beanFactory);​ try { // 4 BeanFactory準備工作完成后進行的后置處理工作； // 4.1）、抽象的方法，當前未做處理。子類通過重寫這個方法來在BeanFactory創建并預準備完成以后做進一步的設置 postProcessBeanFactory(beanFactory); /**************************以上是BeanFactory的創建及預準備工作 ****************/ // 5 執行BeanFactoryPostProcessor的方法；//BeanFactoryPostProcessor：BeanFactory的后置處理器。在BeanFactory標準初始化之后執行的；//他的重要兩個接口：BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor invokeBeanFactoryPostProcessors(beanFactory);​ //6 注冊BeanPostProcessor（Bean的后置處理器） registerBeanPostProcessors(beanFactory);​ // 7 initMessageSource();初始化MessageSource組件（做國際化功能；消息綁定，消息解析）； initMessageSource();​ // 8 初始化事件派發器 initApplicationEventMulticaster();​ // 9 子類重寫這個方法，在容器刷新的時候可以自定義邏輯； onRefresh();​ // 10 給容器中將所有項目里面的ApplicationListener注冊進來 registerListeners(); ​ // 11.初始化所有剩下的單實例bean； finishBeanFactoryInitialization(beanFactory);​ // 12.完成BeanFactory的初始化創建工作；IOC容器就創建完成； 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(); } } }

1 、prepareRefresh()刷新前的預處理;

//刷新前的預處理;protected void prepareRefresh() { this.startupDate = System.currentTimeMillis(); this.closed.set(false); this.active.set(true);​ if (logger.isInfoEnabled()) { logger.info('Refreshing ' + this); } // 初始化一些屬性設置;子類自定義個性化的屬性設置方法； initPropertySources(); // 校驗配置文件的屬性，合法性 getEnvironment().validateRequiredProperties(); //保存容器中的一些事件 this.earlyApplicationEvents = new LinkedHashSet<ApplicationEvent>();}

2、 obtainFreshBeanFactory();創建了一個BeanFactory

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { refreshBeanFactory(); //創建了一個this.beanFactory = new DefaultListableBeanFactory();設置了序列化的ID //返回剛才創建的DefaultListableBeanFactory ConfigurableListableBeanFactory beanFactory = getBeanFactory(); if (logger.isDebugEnabled()) { logger.debug('Bean factory for ' + getDisplayName() + ': ' + beanFactory); } return beanFactory;}

3、 BeanFactory的預準備工作

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) { // 1）、設置BeanFactory的類加載器 beanFactory.setBeanClassLoader(getClassLoader()); // 1）、設置支持表達式解析器 beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader())); beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));​ // 2）、添加部分BeanPostProcessor【ApplicationContextAwareProcessor】 beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this)); // 3）、設置忽略的自動裝配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx； // 這些接口的實現類不能通過類型來自動注入 beanFactory.ignoreDependencyInterface(EnvironmentAware.class); beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class); beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class); beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class); beanFactory.ignoreDependencyInterface(MessageSourceAware.class); beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);​ // 4）、注冊可以解析的自動裝配；我們能直接在任何組件中自動注入： //BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext /* 其他組件中可以通過下面方式直接注冊使用 @autowired BeanFactory beanFactory */ beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency(ResourceLoader.class, this); beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this); beanFactory.registerResolvableDependency(ApplicationContext.class, this);​ // 5）、添加BeanPostProcessor【ApplicationListenerDetector】后置處理器，在bean初始化前后的一些工作 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));​ // 6）、添加編譯時的AspectJ； if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); // Set a temporary ClassLoader for type matching. beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); }​ // 7）、給BeanFactory中注冊一些能用的組件； if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) { // 環境信息ConfigurableEnvironment beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment()); } //系統屬性，systemProperties【Map<String, Object>】 if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties()); } //系統環境變量systemEnvironment【Map<String, Object>】 if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment()); }}

5 執行BeanFactoryPostProcessor的后置處理器方法（BeanFactory）；

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { //執行BeanFactoryPostProcessor的方法 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())); }}

5.1 執行invokeBeanFactoryPostProcessors

public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {​ // Invoke BeanDefinitionRegistryPostProcessors first, if any. Set<String> processedBeans = new HashSet<String>(); // 判斷beanFatory類型 if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>(); List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>(); //得到所有的BeanFactoryPostProcessor 遍歷 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<BeanDefinitionRegistryPostProcessor>();​ //從容器中獲取所有的BeanDefinitionRegistryPostProcessor， String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); // 第一步，先執行實現了PriorityOrdered接口的BeanDefinitionRegistryPostProcessor for (String ppName : postProcessorNames) { if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } //排序 sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); //執行BeanDefinitionRegistryPostProcessor的 postProcessor.postProcessBeanDefinitionRegistry(registry) invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear();​ // 在執行實現了Ordered順序接口的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); } } //排序 sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); //執行postProcessor.postProcessBeanDefinitionRegistry(registry) invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear();​ // 最后執行沒有實現任何優先級或者是順序接口的BeanDefinitionRegistryPostProcessors； 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(); }​ // 現在執行 BeanFactoryPostProcessor的postProcessBeanFactory()方法 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); }​ else { // Invoke factory processors registered with the context instance. invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); }​ //再執行BeanFactoryPostProcessor的方法 //1）、獲取所有的BeanFactoryPostProcessor 和執行BeanDefinitionRegistryPostProcessors的接口邏輯一樣 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);​ List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); List<String> orderedPostProcessorNames = new ArrayList<String>(); List<String> nonOrderedPostProcessorNames = new ArrayList<String>(); //把BeanFactoryPostProcessor 分類 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); } }​ // 2）、看先執行實現了PriorityOrdered優先級接口的BeanFactoryPostProcessor、 sortPostProcessors(priorityOrderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);​ // 3）、在執行實現了Ordered順序接口的BeanFactoryPostProcessor； List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : orderedPostProcessorNames) { orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } sortPostProcessors(orderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);​ // 4）、最后執行沒有實現任何優先級或者是順序接口的BeanFactoryPostProcessor； List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : nonOrderedPostProcessorNames) { nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory); beanFactory.clearMetadataCache();}

6、注冊BeanPostProcessor（Bean的后置處理器）

bean的創建攔截器

不同接口類型的BeanPostProcessor；在Bean創建前后的執行時機是不一樣的

BeanPostProcessor、 DestructionAwareBeanPostProcessor、 InstantiationAwareBeanPostProcessor、 在createBean()方法中處理的，bean創建之前調用的 SmartInstantiationAwareBeanPostProcessor、 MergedBeanDefinitionPostProcessor【internalPostProcessors】 （bean創建完成后調用，11章節中）

registerBeanPostProcessors(beanFactory);

​public static void registerBeanPostProcessors( ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {//1）、獲取所有的 BeanPostProcessor;后置處理器都默認可以通過PriorityOrdered、Ordered接口來執行優先級 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);​ //檢查器，檢查所有的BeanPostProcessor 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<BeanPostProcessor>(); List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>(); List<String> orderedPostProcessorNames = new ArrayList<String>(); List<String> nonOrderedPostProcessorNames = new ArrayList<String>(); 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); } }​ /* 2）、先注冊PriorityOrdered優先級接口的BeanPostProcessor； 把每一個BeanPostProcessor；添加到BeanFactory中 beanFactory.addBeanPostProcessor(postProcessor);*/ sortPostProcessors(priorityOrderedPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);​ // 3）、再注冊Ordered接口的 List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>(); 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);​ // 4）、最后注冊沒有實現任何優先級接口的 List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>(); for (String ppName : nonOrderedPostProcessorNames) { BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class); nonOrderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);​ // 5）、最終注冊MergedBeanDefinitionPostProcessor； sortPostProcessors(internalPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, internalPostProcessors);​ // 6）、注冊一個ApplicationListenerDetector；判斷創建完成的bean是否監聽器 /* 在Bean創建完成后ApplicationListenerDetector.postProcessAfterInitialization()中檢查是否是ApplicationListener 類型，如果是applicationContext.addApplicationListener((ApplicationListener<?>) bean);如果是添加到容器中 */ beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));}

7、initMessageSource();國際化

初始化MessageSource組件（做國際化功能；消息綁定，消息解析）；

​protected void initMessageSource() { // 1）、獲取BeanFactory ConfigurableListableBeanFactory beanFactory = getBeanFactory(); /* 2）、看容器中是否有id為messageSource的，類型是MessageSource的組件 如果有賦值給messageSource，如果沒有自己創建一個DelegatingMessageSource； MessageSource作用：取出國際化配置文件中的某個key的值；能按照區域信息獲?。?*/ 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.isDebugEnabled()) { logger.debug('Using MessageSource [' + this.messageSource + ']'); } } else { // 如果沒有自己創建一個DelegatingMessageSource； DelegatingMessageSource dms = new DelegatingMessageSource(); dms.setParentMessageSource(getInternalParentMessageSource()); this.messageSource = dms; //把創建好的messageSource注冊到容器中，以后獲取國際化配置文件的值的時候，可以自動注入MessageSource； //注入后通過這個方法使用MessageSource.getMessage(String code, Object[] args, String defaultMessage, Locale locale); beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource); if (logger.isDebugEnabled()) { logger.debug('Unable to locate MessageSource with name ’' + MESSAGE_SOURCE_BEAN_NAME + '’: using default [' + this.messageSource + ']'); } }}

8、初始化事件派發器initApplicationEventMulticaster()

​protected void initApplicationEventMulticaster() { //1）、獲取BeanFactory ConfigurableListableBeanFactory beanFactory = getBeanFactory(); //判斷容器中是否有applicationEventMulticaster 的這個bean ,如果有獲取，沒有創建 if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) { //2）、從BeanFactory中獲取applicationEventMulticaster的ApplicationEventMulticaster； this.applicationEventMulticaster = beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class); if (logger.isDebugEnabled()) { logger.debug('Using ApplicationEventMulticaster [' + this.applicationEventMulticaster + ']'); } } else { //3) 個SimpleApplicationEventMulticaster 類型的 applicationEventMulticaster this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory); //4）、將創建的ApplicationEventMulticaster添加到BeanFactory中，以后其他組件直接自動注入 beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster); if (logger.isDebugEnabled()) { logger.debug('Unable to locate ApplicationEventMulticaster with name ’' + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + '’: using default [' + this.applicationEventMulticaster + ']'); } }}

9、onRefresh();留給子容器（子類）

1、子類重寫AbstractApplicationContext.onRefresh()這個方法，在容器刷新的時候可以自定義邏輯；

10、registerListeners();檢查和注冊 Listener

將所有項目里面的ApplicationListener注冊到容器中；

​protected void registerListeners() { //1、從容器中拿到所有的ApplicationListener for (ApplicationListener<?> listener : getApplicationListeners()) { //2、將每個監聽器添加到事件派發器中； getApplicationEventMulticaster().addApplicationListener(listener); }​ // 1.獲取所有的ApplicationListener String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false); for (String listenerBeanName : listenerBeanNames) { //2、將每個監聽器添加到事件派發器中； getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName); }​ // earlyApplicationEvents 中保存之前的事件， Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents; this.earlyApplicationEvents = null; if (earlyEventsToProcess != null) { for (ApplicationEvent earlyEvent : earlyEventsToProcess) { //3、派發之前步驟產生的事件； getApplicationEventMulticaster().multicastEvent(earlyEvent); } }}

11、初始化所有剩下的單實例bean；finishBeanFactoryInitialization(beanFactory);

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) { // 類型裝換器 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)); }​ //值解析器 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();​ // 初始化剩下的單實例bean beanFactory.preInstantiateSingletons();}

11.1 beanFactory.preInstantiateSingletons()初始化剩下的單實例bean

//preInstantiateSingletons():781, DefaultListableBeanFactory public void preInstantiateSingletons() throws BeansException { if (this.logger.isDebugEnabled()) { this.logger.debug('Pre-instantiating singletons in ' + this); } //1）、獲取容器中的所有Bean，依次進行初始化和創建對象 List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames); for (String beanName : beanNames) { //2）、獲取Bean的定義信息；RootBeanDefinition RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); //3）、Bean不是抽象的，是單實例的，不是懶加載； if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) { // 3.1）、判斷是否是FactoryBean；是否是實現FactoryBean接口的Bean； if (isFactoryBean(beanName)) { final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName); boolean isEagerInit; if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) { isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() { @Override public Boolean run() { return ((SmartFactoryBean<?>) factory).isEagerInit(); } }, getAccessControlContext()); } else { isEagerInit = (factory instanceof SmartFactoryBean && ((SmartFactoryBean<?>) factory).isEagerInit()); } if (isEagerInit) { getBean(beanName); } } else { //3.2）、不是工廠Bean。利用getBean(beanName);創建對象 getBean(beanName); //詳情請見 （11.1.3.2 創建bean ->doGetBean）章節 } } }​ // 循環所有的bean for (String beanName : beanNames) { Object singletonInstance = getSingleton(beanName); //判斷bean是否實現了SmartInitializingSingleton 接口如果是；就執行afterSingletonsInstantiated()； if (singletonInstance instanceof SmartInitializingSingleton) { final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance; if (System.getSecurityManager() != null) { AccessController.doPrivileged(new PrivilegedAction<Object>() { @Override public Object run() { smartSingleton.afterSingletonsInstantiated(); return null; } }, getAccessControlContext()); } else { //執行實現類的afterSingletonsInstantiated()； smartSingleton.afterSingletonsInstantiated(); } } }}

11.1.3.2 創建bean ->doGetBean

AbstractBeanFactory.doGetBean()方法

5）、將創建的Bean添加到緩存中singletonObjects；ioc容器就是這些Map；很多的Map里面保存了單實例Bean，環境信息。。。。；

protected <T> T doGetBean( final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly) throws BeansException {​ final String beanName = transformedBeanName(name); Object bean;​/**2、先獲取緩存中保存的單實例Bean。如果能獲取到說明這個Bean之前被創建過（所有創建過的單實例Bean都會被緩存起來）從private final Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256);獲取的 **/ Object sharedInstance = getSingleton(beanName); //如果沒有獲取到創建bean if (sharedInstance != null && args == null) { if (logger.isDebugEnabled()) { if (isSingletonCurrentlyInCreation(beanName)) { logger.debug('Returning eagerly cached instance of singleton bean ’' + beanName +'’ that is not fully initialized yet - a consequence of a circular reference'); } else { logger.debug('Returning cached instance of singleton bean ’' + beanName + '’'); } } bean = getObjectForBeanInstance(sharedInstance, name, beanName, null); }​ else {//3、緩存中獲取不到，開始Bean的創建對象流程； // Fail if we’re already creating this bean instance: // We’re assumably within a circular reference. if (isPrototypeCurrentlyInCreation(beanName)) { throw new BeanCurrentlyInCreationException(beanName); }​ // 獲取父beanFatory 檢查這個bean是否創建了 BeanFactory parentBeanFactory = getParentBeanFactory(); if (parentBeanFactory != null && !containsBeanDefinition(beanName)) { // Not found -> check parent. String nameToLookup = originalBeanName(name); if (args != null) { return (T) parentBeanFactory.getBean(nameToLookup, args); } else { return parentBeanFactory.getBean(nameToLookup, requiredType); } }​ // 4、標記當前bean已經被創建 if (!typeCheckOnly) { markBeanAsCreated(beanName); }​ try { // 5、獲取Bean的定義信息； final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName); checkMergedBeanDefinition(mbd, beanName, args);​ // 6、【獲取當前Bean依賴的其他Bean;如果有按照getBean()把依賴的Bean先創建出來；】 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); getBean(dep); //先創建依賴的bean } }​ // 啟動單實例的bean的創建流程 if (mbd.isSingleton()) { //獲取到單實例bean后，添加到緩存中 singletonObjects（） //Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256); sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() { @Override public Object getObject() throws BeansException { try { //創建Bean ,見11.1.3.2.6.1 return createBean(beanName, mbd, args); } catch (BeansException ex) { destroySingleton(beanName); throw ex; } } }); bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd); }// 下面部分不重要了 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, new ObjectFactory<Object>() { @Override public Object getObject() throws BeansException { 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 && bean != null && !requiredType.isInstance(bean)) { try { return getTypeConverter().convertIfNecessary(bean, requiredType); } catch (TypeMismatchException ex) { if (logger.isDebugEnabled()) { logger.debug('Failed to convert bean ’' + name + '’ to required type ’' +ClassUtils.getQualifiedName(requiredType) + '’', ex); } throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass()); } } return (T) bean;}

11.1.3.2.6.1 創建單實例bean

AbstractAutowireCapableBeanFactory.createBean() 這個類中

​protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException { if (logger.isDebugEnabled()) { logger.debug('Creating instance of bean ’' + beanName + '’'); } RootBeanDefinition mbdToUse = mbd; //bean定義信息​ // 解析bean的類型 Class<?> resolvedClass = resolveBeanClass(mbd, beanName); if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) { mbdToUse = new RootBeanDefinition(mbd); mbdToUse.setBeanClass(resolvedClass); }​ // Prepare method overrides. try { mbdToUse.prepareMethodOverrides(); } catch (BeanDefinitionValidationException ex) { throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(), beanName, 'Validation of method overrides failed', ex); }​ try { //讓BeanPostProcessor先攔截返回代理對象； /** 判斷是否為：InstantiationAwareBeanPostProcessor 的，如果是執行前后置方法 【InstantiationAwareBeanPostProcessor】：提前執行； 先觸發：postProcessBeforeInstantiation()； 如果有返回值：再觸發postProcessAfterInitialization()； **/ Object bean = resolveBeforeInstantiation(beanName, mbdToUse); if (bean != null) { //如果 有對象返回 return bean; } } catch (Throwable ex) { throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName, 'BeanPostProcessor before instantiation of bean failed', ex); } // 沒有對象 創建一個bean Object beanInstance = doCreateBean(beanName, mbdToUse, args); if (logger.isDebugEnabled()) { logger.debug('Finished creating instance of bean ’' + beanName + '’'); } //返回創建的bean return beanInstance;}

1、doCreateBean()創建一個bean

后置處理器：MergedBeanDefinitionPostProcessor ，bean實例化之后調用

//doCreateBean():508, AbstractAutowireCapableBeanFactory 類中protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) throws BeanCreationException {​ // bean的包裝 BeanWrapper instanceWrapper = null; if (mbd.isSingleton()) { instanceWrapper = this.factoryBeanInstanceCache.remove(beanName); } if (instanceWrapper == null) { // 1）、【創建Bean實例】利用工廠方法或者對象的構造器創建出Bean實例； instanceWrapper = createBeanInstance(beanName, mbd, args); } final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null); Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null); mbd.resolvedTargetType = beanType;​ // Allow post-processors to modify the merged bean definition. synchronized (mbd.postProcessingLock) { if (!mbd.postProcessed) { try { //調用MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition(mbd, beanType, beanName); //判斷是否為：MergedBeanDefinitionPostProcessor 類型的，如果是，調用方法 //MergedBeanDefinitionPostProcessor 后置處理器是在bean實例換之后調用的 applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName); } catch (Throwable ex) { throw new BeanCreationException(mbd.getResourceDescription(), beanName, 'Post-processing of merged bean definition failed', ex); } mbd.postProcessed = true; } }​ //判斷bean 是否為單實例的，如果是單實例的添加到緩存中 boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences && isSingletonCurrentlyInCreation(beanName)); if (earlySingletonExposure) { if (logger.isDebugEnabled()) { logger.debug('Eagerly caching bean ’' + beanName + '’ to allow for resolving potential circular references'); } //添加bean到緩存中 addSingletonFactory(beanName, new ObjectFactory<Object>() { @Override public Object getObject() throws BeansException { return getEarlyBeanReference(beanName, mbd, bean); } }); }​ // Initialize the bean instance. Object exposedObject = bean; try { //為bean 賦值,見1.1部分 populateBean(beanName, mbd, instanceWrapper); if (exposedObject != null) { // 4）、【Bean初始化】 exposedObject = initializeBean(beanName, exposedObject, mbd); } } catch (Throwable ex) { if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) { throw (BeanCreationException) ex; } else { throw new BeanCreationException( mbd.getResourceDescription(), beanName, 'Initialization of bean failed', ex); } }​ if (earlySingletonExposure) { //獲取單實例bean,此時已經創建好了 Object earlySingletonReference = getSingleton(beanName, false); if (earlySingletonReference != null) { if (exposedObject == bean) { exposedObject = earlySingletonReference; } else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) { String[] dependentBeans = getDependentBeans(beanName); Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length); for (String dependentBean : dependentBeans) { if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) { actualDependentBeans.add(dependentBean); } } if (!actualDependentBeans.isEmpty()) { throw new BeanCurrentlyInCreationException(beanName,'Bean with name ’' + beanName + '’ has been injected into other beans [' +StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +'] in its raw version as part of a circular reference, but has eventually been ' +'wrapped. This means that said other beans do not use the final version of the ' +'bean. This is often the result of over-eager type matching - consider using ' +'’getBeanNamesOfType’ with the ’allowEagerInit’ flag turned off, for example.'); } } } }​ // 5）、注冊實現了DisposableBean 接口Bean的銷毀方法；只是注冊沒有去執行，容器關閉之后才去調用的 try { registerDisposableBeanIfNecessary(beanName, bean, mbd); } catch (BeanDefinitionValidationException ex) { throw new BeanCreationException( mbd.getResourceDescription(), beanName, 'Invalid destruction signature', ex); }​ return exposedObject;}

1.1 populateBean()創建bean后屬性賦值

//populateBean():1204, AbstractAutowireCapableBeanFactory protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) { PropertyValues pvs = mbd.getPropertyValues();​ if (bw == null) { if (!pvs.isEmpty()) { throw new BeanCreationException( mbd.getResourceDescription(), beanName, 'Cannot apply property values to null instance'); } else { // Skip property population phase for null instance. return; } }​ // Give any InstantiationAwareBeanPostProcessors the opportunity to modify the // state of the bean before properties are set. This can be used, for example, // to support styles of field injection. boolean continueWithPropertyPopulation = true;​ //賦值之前： /* 1）、拿到InstantiationAwareBeanPostProcessor后置處理器； 執行處理器的postProcessAfterInstantiation()； 方法*/ if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) { for (BeanPostProcessor bp : getBeanPostProcessors()) { if (bp instanceof InstantiationAwareBeanPostProcessor) { InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp; //執行 if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) { continueWithPropertyPopulation = false; break; } } } }​ if (!continueWithPropertyPopulation) { return; }​ if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME || mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) { MutablePropertyValues newPvs = new MutablePropertyValues(pvs);​ // autowire 按name注入 if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) { autowireByName(beanName, mbd, bw, newPvs); }​ // autowire 按類型注入 if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) { autowireByType(beanName, mbd, bw, newPvs); }​ pvs = newPvs; }​ boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors(); boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);/*2）、拿到InstantiationAwareBeanPostProcessor后置處理器； 執行 postProcessPropertyValues()； 獲取到屬性的值，此時還未賦值*/ if (hasInstAwareBpps || needsDepCheck) { PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching); if (hasInstAwareBpps) { for (BeanPostProcessor bp : getBeanPostProcessors()) { if (bp instanceof InstantiationAwareBeanPostProcessor) { InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp; pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName); if (pvs == null) { return; } } } } if (needsDepCheck) { checkDependencies(beanName, mbd, filteredPds, pvs); } }//=====賦值之前：=== //3）、應用Bean屬性的值；為屬性利用setter方法等進行賦值； applyPropertyValues(beanName, mbd, bw, pvs);}

1.2 、Bean初始化 initializeBean

initializeBean():1605, AbstractAutowireCapableBeanFactory

//初始化protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) { if (System.getSecurityManager() != null) { AccessController.doPrivileged(new PrivilegedAction<Object>() { @Override public Object run() { invokeAwareMethods(beanName, bean); return null; } }, getAccessControlContext()); } else { //1）、【執行Aware接口方法】invokeAwareMethods(beanName, bean);執行xxxAware接口的方法 //判斷是否實現了 BeanNameAwareBeanClassLoaderAwareBeanFactoryAware 這些接口的bean，如果是執行相應的方法 invokeAwareMethods(beanName, bean); }​ Object wrappedBean = bean; if (mbd == null || !mbd.isSynthetic()) { //2）、【執行后置處理器BeanPostProcessor初始化之前】 執行所有的 BeanPostProcessor.postProcessBeforeInitialization（）; wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); }​ try { //3）、【執行初始化方法】 invokeInitMethods(beanName, wrappedBean, mbd); } catch (Throwable ex) { throw new BeanCreationException( (mbd != null ? mbd.getResourceDescription() : null), beanName, 'Invocation of init method failed', ex); } //4）、【執行后置處理器初始化之后】 執行所有的beanProcessor.postProcessAfterInitialization(result, beanName);方法 if (mbd == null || !mbd.isSynthetic()) { wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName); } return wrappedBean;}

1.2.1 執行bean的初始化方法init

1）、是否是InitializingBean接口的實現；執行接口規定的初始化；

2）、是否自定義初始化方法；通過注解的方式添加了initMethod方法的，

​ 例如： @Bean(initMethod='init',destroyMethod='detory')

//invokeInitMethods():1667, AbstractAutowireCapableBeanFactory protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd) throws Throwable {//1）、是否是InitializingBean接口的實現；執行接口規定的初始化 ,執行afterPropertiesSet()這個方法； boolean isInitializingBean = (bean instanceof InitializingBean); if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod('afterPropertiesSet'))) { if (logger.isDebugEnabled()) { logger.debug('Invoking afterPropertiesSet() on bean with name ’' + beanName + '’'); } if (System.getSecurityManager() != null) { try { AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() { @Override public Object run() throws Exception { ((InitializingBean) bean).afterPropertiesSet(); return null; } }, getAccessControlContext()); } catch (PrivilegedActionException pae) { throw pae.getException(); } } else { //執行實現InitializingBean的afterPropertiesSet方法 ((InitializingBean) bean).afterPropertiesSet(); } }​ if (mbd != null) { //執行通過注解自定義的initMethod 方法 String initMethodName = mbd.getInitMethodName(); if (initMethodName != null && !(isInitializingBean && 'afterPropertiesSet'.equals(initMethodName)) && !mbd.isExternallyManagedInitMethod(initMethodName)) { invokeCustomInitMethod(beanName, bean, mbd); } }}

12、完成BeanFactory的初始化創建工作；IOC容器就創建完成；刷新

protected void finishRefresh() { //1. 初始化生命周期有關的后置處理器，BeanFactory創建完成后刷新相關的工作 //默認從容器中找是否有lifecycleProcessor的組件【LifecycleProcessor】；如果沒有new DefaultLifecycleProcessor();加入到容器； initLifecycleProcessor(); //2. 拿到前面定義的生命周期處理器（LifecycleProcessor）；回調onRefresh()； getLifecycleProcessor().onRefresh();​ //3. 發布容器刷新完成事件； publishEvent(new ContextRefreshedEvent(this));​ //4.暴露 LiveBeansView.registerApplicationContext(this);}

二、Spring 啟動流程的總結

1）、Spring容器在啟動的時候，先會保存所有注冊進來的Bean的定義信息；

1）、xml注冊bean；<bean>

2）、注解注冊Bean；@Service、@Component、@Bean、xxx

2）、Spring容器會合適的時機創建這些Bean

1）、用到這個bean的時候；利用getBean創建bean；創建好以后保存在容器中；

2）、統一創建剩下所有的bean的時候；finishBeanFactoryInitialization()；

3）、后置處理器；BeanPostProcessor

1）、每一個bean創建完成，都會使用各種后置處理器進行處理；來增強bean的功能；

AutowiredAnnotationBeanPostProcessor:處理自動注入

AnnotationAwareAspectJAutoProxyCreator:來做AOP功能；

xxx....

增強的功能注解：

AsyncAnnotationBeanPostProcessor

....

4）、事件驅動模型；

ApplicationListener；事件監聽；

ApplicationEventMulticaster；事件派發：

總結

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