参考源

《Spring源码深度解析(第2版)》

版本

本文章基于 Spring 5.3.15

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Spring IOC 的核心是 AbstractApplicationContext 的 refresh 方法。

其中一共有 13 个主要方法，这里分析第 12 个：finishRefresh。

1 AbstractApplicationContext

1-1 完成刷新过程

finishRefresh()

protected void finishRefresh() {   // 清除资源缓存   clearResourceCaches();   // 初始化生命周期处理器   initLifecycleProcessor();   // 获取生命周期处理器   // 刷新生命周期处理器   getLifecycleProcessor().onRefresh();   // 发布事件   publishEvent(new ContextRefreshedEvent(this));   if (!NativeDetector.inNativeImage()) {      LiveBeansView.registerApplicationContext(this);   }}

1-2 清除资源缓存

clearResourceCaches()

2 DefaultResourceLoader

private final Map
    
     , Map
     
      > resourceCaches = new ConcurrentHashMap<>(4);public void clearResourceCaches() {   this.resourceCaches.clear();}
     
    

1 AbstractApplicationContext

1-2 初始化生命周期处理器

initLifecycleProcessor()

protected void initLifecycleProcessor() {   ConfigurableListableBeanFactory beanFactory = getBeanFactory();   if (beanFactory.containsLocalBean(LIFECYCLE_PROCESSOR_BEAN_NAME)) {      this.lifecycleProcessor = beanFactory.getBean(LIFECYCLE_PROCESSOR_BEAN_NAME, LifecycleProcessor.class);      if (logger.isTraceEnabled()) {         logger.trace("Using LifecycleProcessor [" + this.lifecycleProcessor + "]");      }   } else {      DefaultLifecycleProcessor defaultProcessor = new DefaultLifecycleProcessor();      defaultProcessor.setBeanFactory(beanFactory);      this.lifecycleProcessor = defaultProcessor;      beanFactory.registerSingleton(LIFECYCLE_PROCESSOR_BEAN_NAME, this.lifecycleProcessor);      if (logger.isTraceEnabled()) {         logger.trace("No '" + LIFECYCLE_PROCESSOR_BEAN_NAME + "' bean, using " + "[" + this.lifecycleProcessor.getClass().getSimpleName() + "]");      }   }}

1-2 获取生命周期处理器

getLifecycleProcessor()

private ResourcePatternResolver resourcePatternResolver;LifecycleProcessor getLifecycleProcessor() throws IllegalStateException {   if (this.lifecycleProcessor == null) {      throw new IllegalStateException("LifecycleProcessor not initialized - " + "call 'refresh' before invoking lifecycle methods via the context: " + this);   }   return this.lifecycleProcessor;}

if (this.lifecycleProcessor == null) 由于 this.lifecycleProcessor 在前面已经定义，这里直接返回。

1-2 刷新生命周期处理器

onRefresh()

3 DefaultLifecycleProcessor

public void onRefresh() {   // 启动 Beans   startBeans(true);   this.running = true;}

3-1 启动 Beans

startBeans(true)

private void startBeans(boolean autoStartupOnly) {   // 获取 Bean 生命周期    Map
    
      lifecycleBeans = getLifecycleBeans();   Map
     
       phases = new TreeMap<>();   lifecycleBeans.forEach((beanName, bean) -> {      if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {         int phase = getPhase(bean);         phases.computeIfAbsent(               phase,               p -> new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly)         ).add(beanName, bean);      }   });   if (!phases.isEmpty()) {      phases.values().forEach(LifecycleGroup::start);   }}
     
    

3-2 获取 Bean 生命周期

getLifecycleBeans()

protected Map
    
      getLifecycleBeans() {   // 获取 Bean 工厂   ConfigurableListableBeanFactory beanFactory = getBeanFactory();   Map
     
       beans = new LinkedHashMap<>();   String[] beanNames = beanFactory.getBeanNamesForType(Lifecycle.class, false, false);   for (String beanName : beanNames) {      String beanNameToRegister = BeanFactoryUtils.transformedBeanName(beanName);      boolean isFactoryBean = beanFactory.isFactoryBean(beanNameToRegister);      String beanNameToCheck = (isFactoryBean ? BeanFactory.FACTORY_BEAN_PREFIX + beanName : beanName);      if ((beanFactory.containsSingleton(beanNameToRegister) && (!isFactoryBean || matchesBeanType(Lifecycle.class, beanNameToCheck, beanFactory))) || matchesBeanType(SmartLifecycle.class, beanNameToCheck, beanFactory)) {         Object bean = beanFactory.getBean(beanNameToCheck);         if (bean != this && bean instanceof Lifecycle) {            beans.put(beanNameToRegister, (Lifecycle) bean);         }      }   }   return beans;}
     
    

1 AbstractApplicationContext

1-2 发布事件

publishEvent(new ContextRefreshedEvent(this))

public void publishEvent(ApplicationEvent event) {   publishEvent(event, null);}

protected void publishEvent(Object event, @Nullable ResolvableType eventType) {   Assert.notNull(event, "Event must not be null");   ApplicationEvent applicationEvent;   if (event instanceof ApplicationEvent) {      applicationEvent = (ApplicationEvent) event;   } else {      applicationEvent = new PayloadApplicationEvent<>(this, event);      if (eventType == null) {         eventType = ((PayloadApplicationEvent
    ) applicationEvent).getResolvableType();      }   }   if (this.earlyApplicationEvents != null) {      this.earlyApplicationEvents.add(applicationEvent);   } else {      // 获取应用程序事件多播器      // 多播事件      getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);   }   if (this.parent != null) {      if (this.parent instanceof AbstractApplicationContext) {         ((AbstractApplicationContext) this.parent).publishEvent(event, eventType);      } else {         this.parent.publishEvent(event);      }   }}