开始
在SpringIOC中，前面讲述了如何配置BeanDefinition和如何注册BeanDefinition,但是这些知识容器初始化的一部分，在AbstractApplicationContext中的refresh()方法中，可以看到整个初始化过程。
今天就来看看这段曲折的初始化之路
编写一个简单的启动类，打个断点到AbstractApplicationContext中的refresh()方法中。
public class Application {
public static void main(String[] args) {
// setConfig -> call this.refresh()
ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("context.xml");
}
}
先看看refresh中调用了哪些方法：
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();
}
}
}
一张图概览
上面的图是整个初始化的大概流程。
然后把每一步拿出来说明一下吧
refresh()方法流程
文中使用了ClassPathXmlApplicationContext作为容器
1 prepareRefresh()
protected void prepareRefresh() {
// 记录启动时间 然后设立对应的标志位
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isInfoEnabled()) {
logger.info("Refreshing " + this);
}
// 这是扩展方法，由子类去实现
initPropertySources();
// 创建Environment，验证必要的属性
getEnvironment().validateRequiredProperties();
// 初始化容器，用于装载早期的一些事件
this.earlyApplicationEvents = new LinkedHashSet<>();
}
这里主要是做一些准备工作
2 obtainFreshBeanFactory()
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
// 这个方法是子类去实现的
refreshBeanFactory();
// 创建ApplicationContext内部持有的BeanFactory
// getBeanFactory也是留给子类去实现，可以查看AbstractRefreshableApplicationContext和GernericApplicationContext
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (logger.isDebugEnabled()) {
logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
}
return beanFactory;
}
3 prepareBeanFactory(beanFactory)
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 设置beanFactory的classLoader为当前context的classLoader
beanFactory.setBeanClassLoader(getClassLoader());
// 设置EL表达式解析器（Bean初始化完成后填充属性时会用到）
// spring3增加了表达式语言的支持，默认可以使用#{bean.xxx}的形式来调用相关属性值
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
// 设置属性注册解析器PropertyEditor 这个主要是对bean的属性等设置管理的一个工具
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// 注册BeanPostProcessor-ApplicationContextAwareProcessor，从而在Aware接口实现类中的注入applicationContext等等
// 添加了一个处理aware相关接口的beanPostProcessor扩展，主要是使用beanPostProcessor的postProcessBeforeInitialization()前置处理方法实现aware相关接口的功能
// 类似的还有ResourceLoaderAware、ServletContextAware等等等等
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
// 下面是忽略的自动装配
// 自动装配模式下，下面这些接口的实现类，都不会自动装配，自动装配不是@Autowired
// 注意区分ignoreDependencyType,这个是在自动装配时忽略某个类型属性的依赖
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// 如果是BeanFactory的类，就注册beanFactory
// 如果是ResourceLoader、ApplicationEventPublisher、ApplicationContext等等就注入当前对象this(applicationContext对象)
// 此处registerResolvableDependency()方法注意：它会把他们加入到DefaultListableBeanFactory的resolvableDependencies字段里面缓存这，供后面处理依赖注入的时候使用 DefaultListableBeanFactory#resolveDependency处理依赖关系
// 这也是为什么我们可以通过依赖注入的方式，直接注入这几个对象比如ApplicationContext可以直接依赖注入
// 但是需要注意的是：这些Bean，Spring的IOC容器里其实是没有的。beanFactory.getBeanDefinitionNames()和beanFactory.getSingletonNames()都是找不到他们的，所以特别需要理解这一点
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// 在Bean初始化后检查是否实现了ApplicationListener接口
// 是则加入当前的applicationContext的applicationListeners列表
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// 检查容器中是否包含名称为loadTimeWeaver的bean，实际上是增加Aspectj的支持
// AspectJ采用编译期织入、类加载期织入两种方式进行切面的织入
// 类加载期织入简称为LTW（Load Time Weaving）,通过特殊的类加载器来代理JVM默认的类加载器实现
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
// 添加BEAN后置处理器：LoadTimeWeaverAwareProcessor
// 在BEAN初始化之前检查BEAN是否实现了LoadTimeWeaverAware接口，
// 如果是，则进行加载时织入，即静态代理。
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// Set a temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
// 注入一些其它信息的bean，比如environment、systemProperties、SystemEnvironment等
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
}
if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
}
}
这里做的事情比较多，大多是和依赖的处理相关的配置。
4 postProcessBeanFactory(beanFactory)
这里是模板方法，留给子类去实现的逻辑，至此BeanFactory已经准备好
5 invokeBeanFactoryPostProcessors(beanFactory)
实例化并调用所有的BeanFactoryPostProcessor,当前必须是已经注册的
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 调用BeanFactoryPostProcessor
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)
// 如果loadTimeWeaver这个Bean存在，那么就会配置上运行时织入的处理器LoadTimeWeaverAwareProcessor
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
这里有个getBeanFactoryPostProcessors()方法，这个方法是获取AbstractApplicationContext内部的一个List类型属性，保存了手动添加的BeanPostProcessor实例。
重点在PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors中
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// 先执行BeanDefinitionRegistryPostProcessors
// 需要注意的是BeanDefinitionRegistryPostProcessors 为 BeanFactoryPostProcessor 的子接口 它新增了方法：void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry)
// 所以BeanDefinitionRegistryPostProcessors，它可以我们介入，改变Bean的一些定义信息，或者动态注入Bean定义
Set<String> processedBeans = new HashSet<>();
// 只有此beanFactory 是BeanDefinitionRegistry 才能执行BeanDefinitionRegistryPostProcessor
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
// 此处安放了两个容器，一个装载普通的BeanFactoryPostProcessor
// 另外一个装载和Bean定义有关的 BeanDefinitionRegistryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<>();
// 这里是手动添加到ApplicationContext中的
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
// 这里执行post方法，然后然后吧它缓冲起来了，放在了registryProcessors里
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
// 缓冲到普通的处理器
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.
// 接下来，就是去执行Spring容器里面的一些PostProcessor了。
// 先执行实现了PriorityOrdered接口的，然后是Ordered接口的，最后执行剩下的
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
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);
}
}
// 排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
// 此处缓冲起来（需要注意的是，是排序后，再放进去的 这样是最好的）
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 此处把当前持有的执行对象给清空了，需要注意。以方便装载后续执行的处理器们
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 此处逻辑完全同上 处理实现Order接口的RegistryProcessors
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.
// 最后执行，两个排序接口都没有实现的BeanDefinitionRegistryPostProcessor们，并且也缓存起来
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();
}
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
} else {
// Invoke factory processors registered with the context instance.
// 若是普通的Bean工厂，就直接执行set进来的后置处理器即可（因为容器里就没有其它Bean定义了）
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!
// 下面就是开始执行BeanFactoryPostProcessor 基本也是按照上面的顺序来执行的
// 执行使用配置注册的
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) {
// 这里面注意，已经执行过的后置处理器，就不要再执行了
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();
}
这里核心就是调用手动添加到ApplicationContext中的BeanFactoryPostProcessor和使用配置注册到BeanFactory的处理器。
但是同时要处理两个问题：
BeanFactoryPostProcessor的顺序问题(实现了PriorityOrdered > 实现了Ordered > 什么都没实现)- 对于
BeanDefinitionRegistryPostProcessor的处理,在这里面可以动态修改或者增加BeanDefinition
6 registerBeanPostProcessors(beanFactory)
注册BeanPostProcessor
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}
重点戏还是在PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this)
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
// 从所与Bean定义中提取出BeanPostProcessor类型的Bean
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.
// BeanFactory中BeanPostProcessor的总数
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
// 先注册一个BeanPostProcessorChecker
// 这个有什么用呢，下面我会说明
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
// 先按优先级，归类了BeanPostProcessor
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).
// 把ApplicationListenerDetector 移动到最后
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
这里我们获取到了BeanFactory中定义的所有的BeanPostProcessor对象，并添加到AbstractBeanFactory中的List<BeanPostProcessor> beanPostProcessors中，以便后面创建bean的时候调用
这里有一个BeanPostProcessorChecker，这里是为了检测创建Bean的时候是否所有的BeanPostProcessor都已经注册好。
7 initMessageSource()
这部分逻辑比较简单：向容器里注册一个一个事件源的单例Bean：MessageSource
8 initApplicationEventMulticaster()
初始化Spring的事件多播器：ApplicationEventMulticaster
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
this.applicationEventMulticaster = beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
} else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
}
}
检测用户是否自定义，没有就创建默认的
9 onRefresh()
一个模板方法，留给子类实现
10 registerListeners()
上面的过程已经注册好了事件多播器，现在注册监听器
protected void registerListeners() {
for (ApplicationListener<?> listener : getApplicationListeners()) {
// 把手动注册的监听器绑定到广播器
getApplicationEventMulticaster().addApplicationListener(listener);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let post-processors apply to them!
// 取到容器里面的所有的监听器的名称，绑定到广播器 后面会广播出去这些事件的
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// Publish early application events now that we finally have a multicaster...
// 如果存在早期应用事件，这里就直接发布了(同时就把earlyApplicationEvents该字段置为null)
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
11 finishBeanFactoryInitialization(beanFactory)
实例化所有单例的非懒加载的Bean,并完成依赖注入，这里有点复杂
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// 初始化上下文的转换服务，ConversionService是一个类型转换接口
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);
}
// 停止使用临时的类加载器
beanFactory.setTempClassLoader(null);
// 缓存（冻结）所有的bean definition数据，不期望以后会改变
beanFactory.freezeConfiguration();
// 重要的方法 实例化所有剩余的单例Bean
beanFactory.preInstantiateSingletons();
}
接下来就看这个重要的方法DefaultListableBeanFactory#preInstantiateSingletons
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Pre-instantiating singletons in " + this);
}
// 获取所有的beanName
List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
// 初始化所有的非懒加载的单例bean
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
// 不是抽象类， 是单例的，不是懒加载的
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
// 如果是工厂Bean，那就会此工厂Bean放进去
if (isFactoryBean(beanName)) {
final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
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 {
// 非FactoryBean初始化
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();
}
}
}
}
这里面通过FactoryBean定义的，它是懒加载的
创建Bean-getBean(beanName)方法
这里就是对于Bean的依赖的解析，完成Bean的创建，然后对Bean中的属性完成注入。
由于这里内容较多，我们就放到下一次在总结。
12 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);
}
refresh完成后的一些处理
初始化声明周期方法，发布事件等等