Spring源码解析——启动过程详解
基于Spring的启动看看Spring 进行了哪些操作，在前面简单写过，现在详细概述一次。
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);
System.out.println(applicationContext.getBean("userService"));
进入AnnotationConfigApplicationContext
public AnnotationConfigApplicationContext(Class<?>... componentClasses) {
// 1. 创建BeanFactory
// 2. 生成AnnotatedBeanDefinitionReader
// 3. 生成ClassPathBeanDefinitionScanner
this();
// 利用reader把componentClasses注册为一个BeanDefinition
register(componentClasses);
// 调用AbstractApplicationContext的refresh()方法，模板模式，会启动ApplicationContext
// 为什么叫refresh，而不叫start?
refresh();
}
首先会调用父类的构造方法，构造一个BeanFactory为DefaultListableBeanFactory
public GenericApplicationContext() {
this.beanFactory = new DefaultListableBeanFactory();
}
然后执行当前类的构造方法
public AnnotationConfigApplicationContext() {
// 生成并注册5个BeanDefinition
// 1.ConfigurationClassPostProcessor
// 2.AutowiredAnnotationBeanPostProcessor
// 3.CommonAnnotationBeanPostProcessor
// 4.EventListenerMethodProcessor
// 5.DefaultEventListenerFactory
this.reader = new AnnotatedBeanDefinitionReader(this);
// 注册默认的includeFilter
this.scanner = new ClassPathBeanDefinitionScanner(this);
}
//-------------------------------------------------------------------------
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
BeanDefinitionRegistry registry, @Nullable Object source) {
DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
if (beanFactory != null) {
// 设置beanFactory的OrderComparator，为AnnotationAwareOrderComparator
// 它是一个Comparator，是一个比较器，可以用来进行排序，比如new ArrayList<>().sort(Comparator);
if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
}
// 设置自动装配候选者解析式（判断某个bean是不是可以用来进行进行自动注入）
if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
}
}
Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);
// 注册ConfigurationClassPostProcessor类型的BeanDefinition
if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册AutowiredAnnotationBeanPostProcessor类型的BeanDefinition
if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册CommonAnnotationBeanPostProcessor类型的BeanDefinition
// Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册PersistenceAnnotationBeanPostProcessor类型的BeanDefinition
// Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor.
if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition();
try {
def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
AnnotationConfigUtils.class.getClassLoader()));
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
}
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册EventListenerMethodProcessor类型的BeanDefinition
if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
}
// 注册DefaultEventListenerFactory类型的BeanDefinition
if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
}
return beanDefs;
}
//------------------------------------------------------------------------------------
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, @Nullable ResourceLoader resourceLoader) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
// 添加includeFilters，Spring扫描的时候需要利用includeFilters，Spring扫描到某个类时如果能通过includeFilters的验证就证明这个类是一个Bean
// 默认注册一个@Component注解对应的Filter
if (useDefaultFilters) {
registerDefaultFilters();
}
setEnvironment(environment);
setResourceLoader(resourceLoader);
}
主要逻辑是：
- 构造AnnotatedBeanDefinitionReader
- 设置dependencyComparator比较器，可以用来排序，获取@Priority的值，Ordered接口的值，@Order注解的值
- 设置autowireCandidateResolver自动注入候选者解析器，用来判断某个Bean针对当前依赖是否能进行自动注入
- 向BeanFactory中添加ConfigurationClassPostProcessor对应的BeanDefinition，解析配置类BeanDefinitionRegistryPostProcessor，会进行扫描
- 向BeanFactory中添加AutowiredAnnotationBeanPostProcessor对应的BeanDefinition，它是一个InstantiationAwareBeanPostProcessorAdapter，MergedBeanDefinitionPostProcessor，会处理Bean中@Autowired注解，@Value注解进行依赖
- 向BeanFactory中添加CommonAnnotationBeanPostProcessor对应的BeanDefinition，它是一个InstantiationAwareBeanPostProcessor，InitDestroyAnnotationBeanPostProcessor，会处理Bean中的@Resource注解进行依赖注入
- 向BeanFactory中添加EventListenerMethodProcessor对应的BeanDefinition，它是一个BeanFactoryPostProcessor，SmartInitializingSingleton用来解析单例Bean中被@EventListener注解的方法，并封装为ApplicationLister添加到ApplicationContext中
- 构造ClassPathBeanDefinitionScanner（主要作用可以用来扫描在构造过程中添加@Component注解对应的AnnotationTypeFilter到includeFilter中，并注册BeanDefinition），同时进行设置：设置this.includeFilters = AnnotationTypeFilter(Component.class)，设置environment，设置resourceLoader
接着看看register(componentClasses)最底层的实现方法是doRegisterBean，主要就是把componentClasses注册为一个BeanDefinition
/**
* 这个方法是注册一个bean最底层的方法，参数很多
* beanClass表示bean的类型
* name表示bean的名字
* qualifiers表示资格限定器，如果某个类上没有写@Lazy注解，但是在调用registerBean方法时传递了Lazy.class，那么则达到了一样的效果
* supplier表示实例提供器，如果指定了supplier，那么bean的实例是有这个supplier生成的
* customizers表示BeanDefinition自定义器，可以通过customizers对BeanDefinition进行自定义修改
*/
private <T> void doRegisterBean(Class<T> beanClass, @Nullable String name,
@Nullable Class<? extends Annotation>[] qualifiers, @Nullable Supplier<T> supplier,
@Nullable BeanDefinitionCustomizer[] customizers) {
// 直接生成一个AnnotatedGenericBeanDefinition
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(beanClass);
// 判断当前abd是否被标注了@Conditional注解，并判断是否符合所指定的条件，如果不符合，则跳过，不进行注册
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
// 设置supplier、scope属性，以及得到beanName
abd.setInstanceSupplier(supplier);
// @Scope注解的元数据信息
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
abd.setScope(scopeMetadata.getScopeName());
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
// 获取Lazy、Primary、DependsOn、Role、Description注解信息并设置给abd
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
if (qualifiers != null) {
for (Class<? extends Annotation> qualifier : qualifiers) {
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
else {
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
// 使用自定义器修改BeanDefinition
if (customizers != null) {
for (BeanDefinitionCustomizer customizer : customizers) {
customizer.customize(abd);
}
}
// BeanDefinition中是没有beanName的，BeanDefinitionHolder中持有了BeanDefinition,beanName,alias
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
// 解析Scope中的ProxyMode属性，默认为no，不生成代理对象
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
// 注册到registry中
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
接下来主要看看refrsh方法
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
//为刷新准备此上下文，设置其启动日期
//验证Environment中是否包括了必须要有的属性
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
// 刷新BeanFactory，得到一个空的BeanFactory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
// 准备BeanFactory
// 1. 设置BeanFactory的类加载器、表达式解析器、类型转化注册器
// 2. 添加三个BeanPostProcessor，注意是具体的BeanPostProcessor实例对象
// 3. 记录ignoreDependencyInterface
// 4. 记录ResolvableDependency
// 5. 添加三个单例Bean
//相当于拿到空的bf
//el表达式解析器
//默认类型转化注册器
//添加Bean的后置处理器ApplicationContextAwareProcessor
//添加ignoreDependencyInterface
//添加registerResolvableDependency
//添加Bean的后置处理器ApplicationListenerDetector
//往单例池添加Environment对象
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
// 子类可以对BeanFactory进行进一步初始化
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
// BeanFactory准备好了之后，执行BeanFactoryPostProcessor，开始对BeanFactory进行处理
// 默认情况下:
// 此时beanFactory的beanDefinitionMap中有6个BeanDefinition，5个基础BeanDefinition+AppConfig的BeanDefinition
// 而这6个中只有一个BeanFactoryPostProcessor：ConfigurationClassPostProcessor
// 这里会执行ConfigurationClassPostProcessor进行@Component的扫描，扫描得到BeanDefinition，并注册到beanFactory中
// 注意：扫描的过程中可能又会扫描出其他的BeanFactoryPostProcessor，那么这些BeanFactoryPostProcessor也得在这一步执行
//BeanFactoryPostProcessor是bean的后置处理器，处理bf
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
// 从BeanFactory找出扫描得到得BeanPostProcessor，实例化并注册到BeanFactory中
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
// 初始化MessageSource，如果配置了一个名字叫做“messageSource”的BeanDefinition
// 就会把这个Bean创建出来，并赋值给ApplicationContext的messageSource属性
// 这样ApplicationContext就可以使用国际化的功能了
initMessageSource();
// Initialize event multicaster for this context.
// 设置ApplicationContext的applicationEventMulticaster
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
// 执行子类的onRefresh方法
onRefresh();
// Check for listener beans and register them.
// 注册Listener
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
// 完成beanFactory的初始化（实例化非懒加载的单例bean）
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
// 发布事件
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();
}
}
}
将方法分开来概述
- prepareRefresh();
为刷新准备此上下文，设置其启动日期，验证Environment中是否包括了必须要有的属性
protected void prepareRefresh() {
// Switch to active.
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isDebugEnabled()) {
if (logger.isTraceEnabled()) {
logger.trace("Refreshing " + this);
}
else {
logger.debug("Refreshing " + getDisplayName());
}
}
// Initialize any placeholder property sources in the context environment.
// 可以允许子容器设置一些内容到Environment中
initPropertySources();
// Validate that all properties marked as required are resolvable:
// see ConfigurablePropertyResolver#setRequiredProperties
// 可以通过ApplicationContext设置一些Environment中必须要有的属性
// applicationContext.getEnvironment().setRequiredProperties("xxx");
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
if (this.earlyApplicationListeners == null) {
this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// Reset local application listeners to pre-refresh state.
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
this.earlyApplicationEvents = new LinkedHashSet<>();
}
- ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
刷新BeanFactory，得到一个空的BeanFactory
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
// 两个模板，子类负责实现，
// GenericApplicationContext不支持刷新，AbstractRefreshableApplicationContext支持刷新
// AnnotationConfigApplicationContext extends GenericApplicationContext 不支持刷新
// ClassPathXmlApplicationContext extends AbstractXmlApplicationContext extends AbstractRefreshableConfigApplicationContext
// extends AbstractRefreshableApplicationContext支持刷新
refreshBeanFactory();
return getBeanFactory();
}
- prepareBeanFactory(beanFactory)；
//相当于拿到空的bf
//el表达式解析器
//默认类型转化注册器
//添加Bean的后置处理器ApplicationContextAwareProcessor
//添加ignoreDependencyInterface
//添加registerResolvableDependency
//添加Bean的后置处理器ApplicationListenerDetector
//往单例池添加Environment对象
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
//获取ClassLoader
beanFactory.setBeanClassLoader(getClassLoader());
//StandardBeanExpressionResolver el表达式解析器
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
//ResourceEditorRegistrar 默认类型转化注册器
//@Value 只能注入String，但是用Integer也可以接收“123”主要就是这个解决的
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
//ApplicationContextAwareProcessor bean的后置处理器
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
// 如果一个属性对应的set方法在ignoredDependencyInterfaces接口中被定义了，则该属性不会进行自动注入（是Spring中的自动注入，不是@Autowired）
//比如一个bean实现了ApplicationContextAware 重写了set方法，在该set方法上又加了@Autowired则会判断该set方法是自己写的，还是因为实现而来的，进而判断
// ignoredDependencyInterfaces接口中是否被定义了，来决定是否执行多次
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// BeanFactory interface not registered as resolvable type in a plain factory.
// MessageSource registered (and found for autowiring) as a bean.
// 相当于直接把ApplicationContext对象放入Bean工厂中，当getBean(type)时，如果type就是这四个type，则直接返回所设置的实例
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// Register early post-processor for detecting inner beans as ApplicationListeners.
//注册早期的后处理器以检测内部bean作为应用程序侦听器
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
//LoadTimeWeaverAwareProcessor和aop有关
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// Set a temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
// Register default environment beans.
//往单例池添加Environment对象
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());
}
}
-
postProcessBeanFactory(beanFactory);
提供给AbstractApplicationContext的子类进行扩展，具体的子类，可以继续向BeanFactory中再添加一些东西 -
invokeBeanFactoryPostProcessors(beanFactory);
这个后面再详细说，前面也有介绍，主要就是扫描得到BeanDefinition，并注册到beanFactory中 -
registerBeanPostProcessors(beanFactory);
因为上面的步骤完成了扫描，这个过程中程序员可能自己定义了一些BeanPostProcessor，在这一步就会把BeanFactory中所有的BeanPostProcessor找出来并实例化得到一个对象，并添加到BeanFactory中去（属性beanPostProcessors），最后再重新添加一个ApplicationListenerDetector对象（之前其实就添加了过，这里是为了把ApplicationListenerDetector移动到最后）
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
// 获取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.
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
//分类，后面再排序
//internalPostProcessors,orderedPostProcessorNames,nonOrderedPostProcessorNames
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);
// 把priorityOrderedPostProcessors添加到beanFactory中
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
// 把orderedPostProcessors添加到beanFactory中
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// Now, register all regular BeanPostProcessors.
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// Finally, re-register all internal BeanPostProcessors.
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// Re-register post-processor for detecting inner beans as ApplicationListeners,
// moving it to the end of the processor chain (for picking up proxies etc).
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
-
initMessageSource();
如果BeanFactory中存在一个叫做"messageSource"的BeanDefinition，那么就会把这个Bean对象创建出来并赋值给ApplicationContext的messageSource属性，让ApplicationContext拥有国际化的功能 -
initApplicationEventMulticaster();
如果BeanFactory中存在一个叫做"applicationEventMulticaster"的BeanDefinition，那么就会把这个Bean对象创建出来并赋值给ApplicationContext的applicationEventMulticaster属性，让ApplicationContext拥有事件发布的功能 -
onRefresh();
提供给AbstractApplicationContext的子类进行扩展，没用 -
registerListeners();
从BeanFactory中获取ApplicationListener类型的beanName，然后添加到ApplicationContext中的事件广播器applicationEventMulticaster中去，到这一步因为FactoryBean还没有调用getObject()方法生成Bean对象，所以这里要在根据类型找一下ApplicationListener，记录一下对应的beanName
protected void registerListeners() {
// Register statically specified listeners first.
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let post-processors apply to them!
// 到这一步因为FactoryBean还没有调用getObject()方法生成Bean对象，所以这里要在根据类型找一下ApplicationListener，记录一下对应的beanName
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...
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
-
finishBeanFactoryInitialization(beanFactory);
完成BeanFactory的初始化，主要就是实例化非懒加载的单例Bean，前面讲过 -
finishRefresh();
BeanFactory的初始化完后，就到了Spring启动的最后一步了，设置ApplicationContext的lifecycleProcessor，默认情况下设置的是DefaultLifecycleProcessor，调用lifecycleProcessor的onRefresh()方法，如果是DefaultLifecycleProcessor，那么会获取所有类型为Lifecycle的Bean对象，然后调用它的start()方法，这就是ApplicationContext的生命周期扩展机制，发布ContextRefreshedEvent事件
protected void finishRefresh() {
// Clear context-level resource caches (such as ASM metadata from scanning).
clearResourceCaches();
// Initialize lifecycle processor for this context.
//Spring 容器的生命周期
initLifecycleProcessor();
// Propagate refresh to lifecycle processor first.
//默认情况下DefaultLifecycleProcessor的onRefresh方法
//找出Lifecycle Bean 执行 start方法，默认情况下是没有Lifecycle Bean的，需要自己定义
getLifecycleProcessor().onRefresh();
// Publish the final event.
publishEvent(new ContextRefreshedEvent(this));
// Participate in LiveBeansView MBean, if active.
LiveBeansView.registerApplicationContext(this);
}
