Spring 启动流程源码解析之一
一、Spring容器的refresh()
spring version:4.3.12 ，尚硅谷Spring注解驱动开发—源码部分
//refresh():543, AbstractApplicationContext (org.springframework.context.support) public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { //1 刷新前的预处理 prepareRefresh(); //2 获取BeanFactory；刚创建的默认DefaultListableBeanFactory ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); //3 BeanFactory的预准备工作（BeanFactory进行一些设置） prepareBeanFactory(beanFactory); try { // 4 BeanFactory准备工作完成后进行的后置处理工作； // 4.1）、抽象的方法，当前未做处理。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 postProcessBeanFactory(beanFactory); /**************************以上是BeanFactory的创建及预准备工作 ****************/ // 5 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； //他的重要两个接口：BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor invokeBeanFactoryPostProcessors(beanFactory); //6 注册BeanPostProcessor（Bean的后置处理器） registerBeanPostProcessors(beanFactory); // 7 initMessageSource();初始化MessageSource组件（做国际化功能；消息绑定，消息解析）； initMessageSource(); // 8 初始化事件派发器 initApplicationEventMulticaster(); // 9 子类重写这个方法，在容器刷新的时候可以自定义逻辑； onRefresh(); // 10 给容器中将所有项目里面的ApplicationListener注册进来 registerListeners(); // 11.初始化所有剩下的单实例bean； finishBeanFactoryInitialization(beanFactory); // 12.完成BeanFactory的初始化创建工作；IOC容器就创建完成； 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()刷新前的预处理;
//刷新前的预处理; protected void prepareRefresh() { this.startupDate = System.currentTimeMillis(); this.closed.set(false); this.active.set(true); if (logger.isInfoEnabled()) { logger.info("Refreshing " + this); } // 初始化一些属性设置;子类自定义个性化的属性设置方法； initPropertySources(); // 校验配置文件的属性，合法性 getEnvironment().validateRequiredProperties(); //保存容器中的一些事件 this.earlyApplicationEvents = new LinkedHashSet<ApplicationEvent>(); }
2、 obtainFreshBeanFactory();创建了一个BeanFactory
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { refreshBeanFactory(); //创建了一个this.beanFactory = new DefaultListableBeanFactory();设置了序列化的ID //返回刚才创建的DefaultListableBeanFactory ConfigurableListableBeanFactory beanFactory = getBeanFactory(); if (logger.isDebugEnabled()) { logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory); } return beanFactory; }
3、 BeanFactory的预准备工作
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) { // 1）、设置BeanFactory的类加载器 beanFactory.setBeanClassLoader(getClassLoader()); // 1）、设置支持表达式解析器 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）、设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx； // 这些接口的实现类不能通过类型来自动注入 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 /* 其他组件中可以通过下面方式直接注册使用 @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】后置处理器，在bean初始化前后的一些工作 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this)); // 6）、添加编译时的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）、给BeanFactory中注册一些能用的组件； if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) { // 环境信息ConfigurableEnvironment beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment()); } //系统属性，systemProperties【Map<String, Object>】 if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties()); } //系统环境变量systemEnvironment【Map<String, Object>】 if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) { beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment()); } }
5 执行BeanFactoryPostProcessor的后置处理器方法（BeanFactory）；
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { //执行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 执行invokeBeanFactoryPostProcessors
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { // Invoke BeanDefinitionRegistryPostProcessors first, if any. Set<String> processedBeans = new HashSet<String>(); // 判断beanFatory类型 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 遍历 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>(); //从容器中获取所有的BeanDefinitionRegistryPostProcessor， String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); // 第一步，先执行实现了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); //执行BeanDefinitionRegistryPostProcessor的 postProcessor.postProcessBeanDefinitionRegistry(registry) invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // 在执行实现了Ordered顺序接口的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); //执行postProcessor.postProcessBeanDefinitionRegistry(registry) invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // 最后执行没有实现任何优先级或者是顺序接口的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(); } // 现在执行 BeanFactoryPostProcessor的postProcessBeanFactory()方法 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // Invoke factory processors registered with the context instance. invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); } //再执行BeanFactoryPostProcessor的方法 //1）、获取所有的BeanFactoryPostProcessor 和执行BeanDefinitionRegistryPostProcessors的接口逻辑一样 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 分类 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）、看先执行实现了PriorityOrdered优先级接口的BeanFactoryPostProcessor、 sortPostProcessors(priorityOrderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory); // 3）、在执行实现了Ordered顺序接口的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）、最后执行没有实现任何优先级或者是顺序接口的BeanFactoryPostProcessor； List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : nonOrderedPostProcessorNames) { nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory); beanFactory.clearMetadataCache(); }
6、注册BeanPostProcessor（Bean的后置处理器）
bean的创建拦截器
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、 在createBean()方法中处理的，bean创建之前调用的
SmartInstantiationAwareBeanPostProcessor、
MergedBeanDefinitionPostProcessor【internalPostProcessors】 （bean创建完成后调用，11章节中）
registerBeanPostProcessors(beanFactory); public static void registerBeanPostProcessors( ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) { //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 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false); //检查器，检查所有的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）、先注册PriorityOrdered优先级接口的BeanPostProcessor； 把每一个BeanPostProcessor；添加到BeanFactory中 beanFactory.addBeanPostProcessor(postProcessor);*/ sortPostProcessors(priorityOrderedPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors); // 3）、再注册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）、最后注册没有实现任何优先级接口的 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）、最终注册MergedBeanDefinitionPostProcessor； sortPostProcessors(internalPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, internalPostProcessors); // 6）、注册一个ApplicationListenerDetector；判断创建完成的bean是否监听器 /* 在Bean创建完成后ApplicationListenerDetector.postProcessAfterInitialization()中检查是否是ApplicationListener 类型，如果是applicationContext.addApplicationListener((ApplicationListener<?>) bean);如果是添加到容器中 */ beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext)); }
7、initMessageSource();国际化
初始化MessageSource组件（做国际化功能；消息绑定，消息解析）；
protected void initMessageSource() { // 1）、获取BeanFactory ConfigurableListableBeanFactory beanFactory = getBeanFactory(); /* 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作用：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； */ 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 { // 如果没有自己创建一个DelegatingMessageSource； DelegatingMessageSource dms = new DelegatingMessageSource(); dms.setParentMessageSource(getInternalParentMessageSource()); this.messageSource = dms; //把创建好的messageSource注册到容器中，以后获取国际化配置文件的值的时候，可以自动注入MessageSource； //注入后通过这个方法使用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、初始化事件派发器initApplicationEventMulticaster()
protected void initApplicationEventMulticaster() { //1）、获取BeanFactory ConfigurableListableBeanFactory beanFactory = getBeanFactory(); //判断容器中是否有applicationEventMulticaster 的这个bean ,如果有获取，没有创建 if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) { //2）、从BeanFactory中获取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) 个SimpleApplicationEventMulticaster 类型的 applicationEventMulticaster this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory); //4）、将创建的ApplicationEventMulticaster添加到BeanFactory中，以后其他组件直接自动注入 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();留给子容器（子类）
1、子类重写AbstractApplicationContext.onRefresh()这个方法，在容器刷新的时候可以自定义逻辑；
10、registerListeners();检查和注册 Listener
将所有项目里面的ApplicationListener注册到容器中；
protected void registerListeners() { //1、从容器中拿到所有的ApplicationListener for (ApplicationListener<?> listener : getApplicationListeners()) { //2、将每个监听器添加到事件派发器中； getApplicationEventMulticaster().addApplicationListener(listener); } // 1.获取所有的ApplicationListener String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false); for (String listenerBeanName : listenerBeanNames) { //2、将每个监听器添加到事件派发器中； 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、派发之前步骤产生的事件； getApplicationEventMulticaster().multicastEvent(earlyEvent); } } }
11、初始化所有剩下的单实例bean；finishBeanFactoryInitialization(beanFactory);
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) { // 类型装换器 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(); // 初始化剩下的单实例bean beanFactory.preInstantiateSingletons(); }
11.1 beanFactory.preInstantiateSingletons()初始化剩下的单实例bean
//preInstantiateSingletons():781, DefaultListableBeanFactory public void preInstantiateSingletons() throws BeansException { if (this.logger.isDebugEnabled()) { this.logger.debug("Pre-instantiating singletons in " + this); } //1）、获取容器中的所有Bean，依次进行初始化和创建对象 List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames); for (String beanName : beanNames) { //2）、获取Bean的定义信息；RootBeanDefinition RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); //3）、Bean不是抽象的，是单实例的，不是懒加载； if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) { // 3.1）、判断是否是FactoryBean；是否是实现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）、不是工厂Bean。利用getBean(beanName);创建对象 getBean(beanName); //详情请见 （11.1.3.2 创建bean ->doGetBean）章节 } } } // 循环所有的bean for (String beanName : beanNames) { Object singletonInstance = getSingleton(beanName); //判断bean是否实现了SmartInitializingSingleton 接口如果是；就执行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 { //执行实现类的afterSingletonsInstantiated()； smartSingleton.afterSingletonsInstantiated(); } } } }
11.1.3.2 创建bean ->doGetBean
AbstractBeanFactory.doGetBean()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。。。。；
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 **/ Object sharedInstance = getSingleton(beanName); //如果没有获取到创建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、缓存中获取不到，开始Bean的创建对象流程； // Fail if we're already creating this bean instance: // We're assumably within a circular reference. if (isPrototypeCurrentlyInCreation(beanName)) { throw new BeanCurrentlyInCreationException(beanName); } // 获取父beanFatory 检查这个bean是否创建了 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、标记当前bean已经被创建 if (!typeCheckOnly) { markBeanAsCreated(beanName); } try { // 5、获取Bean的定义信息； final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName); checkMergedBeanDefinition(mbd, beanName, args); // 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；】 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); //先创建依赖的bean } } // 启动单实例的bean的创建流程 if (mbd.isSingleton()) { //获取到单实例bean后，添加到缓存中 singletonObjects（） //Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256); sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() { @Override public Object getObject() throws BeansException { try { //创建Bean ,见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 创建单实例bean
AbstractAutowireCapableBeanFactory.createBean() 这个类中
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定义信息 // 解析bean的类型 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 { //让BeanPostProcessor先拦截返回代理对象； /** 判断是否为：InstantiationAwareBeanPostProcessor 的，如果是执行前后置方法 【InstantiationAwareBeanPostProcessor】：提前执行； 先触发：postProcessBeforeInstantiation()； 如果有返回值：再触发postProcessAfterInitialization()； **/ Object bean = resolveBeforeInstantiation(beanName, mbdToUse); if (bean != null) { //如果 有对象返回 return bean; } } catch (Throwable ex) { throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName, "BeanPostProcessor before instantiation of bean failed", ex); } // 没有对象 创建一个bean Object beanInstance = doCreateBean(beanName, mbdToUse, args); if (logger.isDebugEnabled()) { logger.debug("Finished creating instance of bean '" + beanName + "'"); } //返回创建的bean return beanInstance; }
1、doCreateBean()创建一个bean
后置处理器：MergedBeanDefinitionPostProcessor ，bean实例化之后调用
//doCreateBean():508, AbstractAutowireCapableBeanFactory 类中 protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) throws BeanCreationException { // bean的包装 BeanWrapper instanceWrapper = null; if (mbd.isSingleton()) { instanceWrapper = this.factoryBeanInstanceCache.remove(beanName); } if (instanceWrapper == null) { // 1）、【创建Bean实例】利用工厂方法或者对象的构造器创建出Bean实例； 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 { //调用MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition(mbd, beanType, beanName); //判断是否为：MergedBeanDefinitionPostProcessor 类型的，如果是，调用方法 //MergedBeanDefinitionPostProcessor 后置处理器是在bean实例换之后调用的 applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName); } catch (Throwable ex) { throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Post-processing of merged bean definition failed", ex); } mbd.postProcessed = true; } } //判断bean 是否为单实例的，如果是单实例的添加到缓存中 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到缓存中 addSingletonFactory(beanName, new ObjectFactory<Object>() { @Override public Object getObject() throws BeansException { return getEarlyBeanReference(beanName, mbd, bean); } }); } // Initialize the bean instance. Object exposedObject = bean; try { //为bean 赋值,见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) { //获取单实例bean,此时已经创建好了 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）、注册实现了DisposableBean 接口Bean的销毁方法；只是注册没有去执行，容器关闭之后才去调用的 try { registerDisposableBeanIfNecessary(beanName, bean, mbd); } catch (BeanDefinitionValidationException ex) { throw new BeanCreationException( mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex); } return exposedObject; }
1.1 populateBean()创建bean后属性赋值
//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; //赋值之前： /* 1）、拿到InstantiationAwareBeanPostProcessor后置处理器； 执行处理器的postProcessAfterInstantiation()； 方法*/ if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) { for (BeanPostProcessor bp : getBeanPostProcessors()) { if (bp instanceof InstantiationAwareBeanPostProcessor) { InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp; //执行 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 按类型注入 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后置处理器； 执行 postProcessPropertyValues()； 获取到属性的值，此时还未赋值*/ 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); } } //=====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); }
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）、【执行Aware接口方法】invokeAwareMethods(beanName, bean);执行xxxAware接口的方法 //判断是否实现了 BeanNameAware\BeanClassLoaderAware\BeanFactoryAware 这些接口的bean，如果是执行相应的方法 invokeAwareMethods(beanName, bean); } Object wrappedBean = bean; if (mbd == null || !mbd.isSynthetic()) { //2）、【执行后置处理器BeanPostProcessor初始化之前】 执行所有的 BeanPostProcessor.postProcessBeforeInitialization（）; wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); } try { //3）、【执行初始化方法】 invokeInitMethods(beanName, wrappedBean, mbd); } catch (Throwable ex) { throw new BeanCreationException( (mbd != null ? mbd.getResourceDescription() : null), beanName, "Invocation of init method failed", ex); } //4）、【执行后置处理器初始化之后】 执行所有的beanProcessor.postProcessAfterInitialization(result, beanName);方法 if (mbd == null || !mbd.isSynthetic()) { wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName); } return wrappedBean; }
1.2.1 执行bean的初始化方法init
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；通过注解的方式添加了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接口的实现；执行接口规定的初始化 ,执行afterPropertiesSet()这个方法； 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 { //执行实现InitializingBean的afterPropertiesSet方法 ((InitializingBean) bean).afterPropertiesSet(); } } if (mbd != null) { //执行通过注解自定义的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的初始化创建工作；IOC容器就创建完成；刷新
protected void finishRefresh() { //1. 初始化生命周期有关的后置处理器，BeanFactory创建完成后刷新相关的工作 //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； initLifecycleProcessor(); //2. 拿到前面定义的生命周期处理器（LifecycleProcessor）；回调onRefresh()； getLifecycleProcessor().onRefresh(); //3. 发布容器刷新完成事件； publishEvent(new ContextRefreshedEvent(this)); //4.暴露 LiveBeansView.registerApplicationContext(this); }
二、Spring 启动流程的总结
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：
