Spring学习之浅析refresh()执行逻辑(转载)

本文深入解析Spring框架中AbstractApplicationContext的refresh()方法,该方法是Spring Bean加载的核心,定义了整个上下文加载流程。文章详细分析了refresh()方法的12个步骤,包括准备阶段、BeanFactory的创建、BeanPostProcessor的注册、初始化MessageSource等关键环节。

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目录
概览
refresh
明细
1.prepareRefresh
2.obtainFreshBeanFactory
3.prepareBeanFactory
4.postProcessBeanFactory
5. invokeBeanFactoryPostProcessors
6.registerBeanPostProcessors
7.initMessageSource
8.initApplicationEventMulticaster
9.onRefresh
10.registerListeners
11.finishBeanFactoryInitialization
12.finishRefresh

对于AbstractApplicationContex#refresh()方法逻辑,可所谓是贯通spring框架核心逻辑,溪源在debug过程中,理解起来也是懵懵懂懂,自己也买了《Spring源码深度解析》书籍学习其思想和实现逻辑,经过不断的整理学习总结,最终诞生这篇文章,方便后面自己忘记了查看和理解。
下面开始正式踏入refresh方法的整体概览浅析。
概览
refresh
该方法是 Spring Bean 加载的核心,它是 ClassPathXmlApplicationContext 的父类 AbstractApplicationContext 的一个方法 , 顾名思义,用于刷新整个Spring 上下文信息,定义了整个 Spring 上下文加载的流程。
先看下refresh()方法总体:

@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 准备预处理:记录容器的启动时间startupDate, 标记容器为激活,初始化上下文环境如文件路径信息,验证必填属性是否填写
this.prepareRefresh();
// **告诉子类去刷新bean工厂,此方法解析配置文件并将bean信息存储到beanDefinition中,注册到BeanFactory(但是未被初始化,仅将信息写到了beanDefination的map中)**重点方法,下面的操作都基于这个beanFactory进行的
ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
// 设置beanFactory的基本属性:类加载器,添加多个beanPostProcesser
this.prepareBeanFactory(beanFactory);
try {
// 空实现:允许子类上下文中对beanFactory做后期处理
this.postProcessBeanFactory(beanFactory);
/**************************以上是BeanFactory的创建及预准备工作 **************/
// 调用BeanFactoryPostProcessor各个实现类的方法
this.invokeBeanFactoryPostProcessors(beanFactory);
// 注册 BeanPostProcessor 的实现类,注意看和 BeanFactoryPostProcessor 的区别
// 此接口两个方法: postProcessBeforeInitialization 和 postProcessAfterInitialization
// 两个方法分别在 Bean 初始化之前和初始化之后得到执行。注意,到这里 Bean 还没初始化
this.registerBeanPostProcessors(beanFactory);
//初始化ApplicationContext的MessageSource组件(资源文件),如国际化文件,消息解析,绑定等
this.initMessageSource();
//初始化ApplicationContext事件广播器
this.initApplicationEventMulticaster();
// 初始化子类特殊bean(钩子方法)
this.onRefresh();
// 获取所有的事件监听器,并将监听器注册到事件广播器
this.registerListeners();
//
初始化所有singleton bean;**重点方法
this.finishBeanFactoryInitialization(beanFactory);
// 广播事件:ApplicationContext初始化完成
this.finishRefresh();
} catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " + "cancelling refresh attempt: " + ex);
}
// 销毁bean
this.destroyBeans();
// 重置 ‘active’ 标志.
this.cancelRefresh(ex);
throw ex;
}
}

明细
本篇文章,不会仔细往下探讨源码实现逻辑,先总结refresh()方法具体逻辑:

1.prepareRefresh
准备预处理:记录spring容器的启动时间startupDate, 标记容器为激活,初始化上下文环境如文件路径信息,验证必填属性是否填写。

initPropertySources():初始化一些属性设置;子类自定义个性化的属性设置方法;
getEnvironment().validateRequiredProperties():检验属性的合法等;
earlyApplicationEvents= new LinkedHashSet():保存容器中的一些早期的事件;
//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();
}

2.obtainFreshBeanFactory
获取BeanFactory,解析配置文件,生成beanDefinition;

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;
}
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3.prepareBeanFactory
该方法主要负责对BeanFactory的预准备工作,配置beanFactory的基础属性,比如ClassLoader和一些PostProcessor等。
这个方法主要是给BeanFactory设置一些基本的属性,比如类加载器、表达式解析器、属性编辑器,注册几个单例、添加一些不用注入的接口、添加解析依赖项等。

设置BeanFactory的类加载器、支持表达式解析器…
添加部分BeanPostProcessor【ApplicationContextAwareProcessor】
设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx;
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
添加BeanPostProcessor【ApplicationListenerDetector】
添加编译时的AspectJ;
给BeanFactory中注册一些能用的组件;
environment【ConfigurableEnvironment】、
systemProperties【Map<String, Object>】、
systemEnvironment【Map<String, Object>】
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context’s class loader etc.
//设置类加载器
beanFactory.setBeanClassLoader(getClassLoader());
//设置bean表达式解析器,详解见下文
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver());
//资源编辑注册器
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

//添加一个BeanPostProcessor:ApplicationContextAwareProcessor,用于向实现类ApplitionContextAware中,调用setApplicationContext方法,并将ApplicationContext作为参数。
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));

//添加忽略自动装配的接口
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);


// 注册几个解析依赖项,意思是,当一个Bean需要注入对应的类时,使用下面注册的这些类

//比如,如果@Autowire 一个BeanFactory,那么这个BeanFactory实际就是在此处注册的一个对象
//这几项分别是:BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);

// Detect a LoadTimeWeaver and prepare for weaving, if found.
//检查是否由LoadTimeWeaver,如果有loadTimeWeaver的bean,就放入一个BeanPostProcessor:LoadTimeWeaverAwareProcessor
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()));
}

// 注册environment,注册成单例
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
	beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
 //注册systemProperties 成单例
if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
	beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
}
  //注册 systemEnvironment 成单例
if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
	beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
}

}

4.postProcessBeanFactory
主要负责在BeanFactory准备工作完成之后,beanFactory的后置处理工作;

protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
}
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5. invokeBeanFactoryPostProcessors
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.

//用于存放已处理过的Bean
Set<String> processedBeans = new HashSet<String>();

//如果IOC容器是一个BeanDefinitionRegistry,有了注册BeanDefinition的能力,就可以执行BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法
if (beanFactory instanceof BeanDefinitionRegistry) {
    
    BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
    
    //regularPostProcessors用于存放普通的BeanFactoryPostProcessor
    List<BeanFactoryPostProcessor> 
        regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
    
    //registryPostProcessors用于存放 BeanDefinitionRegistryPostProcessor
    List<BeanDefinitionRegistryPostProcessor> 
        registryPostProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>();
    
    //查询通过addBeanFactoryPostProcessor等方法设置进来的的BeanFactoryPostProcessor(不是注册到IOC容器的中)
    for (BeanFactoryPostProcessor postProcessor : getBeanFactoryPostProcessors()) {
        
        //如果是 BeanDefinitionRegistryPostProcessor  ,
        //就先执行它的postProcessBeanDefinitionRegistry,用于向IOC中注册一些BeanDefinition,
        //然后添加到registryPostProcessors队列中
      if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
            BeanDefinitionRegistryPostProcessor registryPostProcessor =
                (BeanDefinitionRegistryPostProcessor) postProcessor;
			  
        	registryPostProcessor.postProcessBeanDefinitionRegistry(registry);
            registryPostProcessors.add(registryPostProcessor);
        }
        else {
            //如果是普通的BeanFactoryPostProcessor,就添加到regularPostProcessors队列中
            regularPostProcessors.add(postProcessor);
        }
    }
    
    //获取IOC容器中注册的BeanDefinitionRegistryPostProcessor,
    //放入到registryPostProcessorBeans中,
    //并按照Order排序
    Map<String, BeanDefinitionRegistryPostProcessor> beanMap =
        beanFactory.getBeansOfType(BeanDefinitionRegistryPostProcessor.class, true, false);
    
    List<BeanDefinitionRegistryPostProcessor> registryPostProcessorBeans =
        new ArrayList<BeanDefinitionRegistryPostProcessor>(beanMap.values());
   
    OrderComparator.sort(registryPostProcessorBeans);
    
    //先调用registryPostProcessorBeans中的所有postProcessBeanDefinitionRegistry方法
    for (BeanDefinitionRegistryPostProcessor postProcessor : registryPostProcessorBeans) {
        postProcessor.postProcessBeanDefinitionRegistry(registry);
    }
    //先调用 registryPostProcessors中的postProcessBeanFactory方法
    //再调用 registryPostProcessorBeans中的postProcessBeanFactory方法
    //最后调用 regularPostProcessors中的postProcessBeanFactory方法
    invokeBeanFactoryPostProcessors(registryPostProcessors, beanFactory);
    invokeBeanFactoryPostProcessors(registryPostProcessorBeans, beanFactory);
    invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
    
    //对于IOC容器中注册的BeanDefinitionRegistryPostProcessor来说,还要放置到processedBeans中,放置重复调用
    processedBeans.addAll(beanMap.keySet());
}
else {
    //如果IOC就是一个普通的BeanFacotry,就直接从context中取出所有的BeanFactoryPostProcessor,并调用他们的postProcessBeanFactory方法
    // Invoke factory processors registered with the context instance.
    invokeBeanFactoryPostProcessors(getBeanFactoryPostProcessors(), beanFactory);
}

// Do not initialize FactoryBeans here: We need to leave all regular beans
// 查询IOC容器中所有的BeanFactoryPostProcessor,有可能上面的BeanDefinitionRegistryPostProcessor刚刚向IOC容器中注册了一些BeanFactoryPostProcessor,所以要在此处全部查出来。
String[] postProcessorNames =
    beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

// 按照 这些BeanFactoryPostProcessor实现的排序接口( PriorityOrdered 和 Ordered)分成3组
//第一组 实现了PriorityOrdered  --- priorityOrderedPostProcessors
//第二组 实现了Ordered          --- orderedPostProcessorNames
//第三组 没有实现排序接口         --- nonOrderedPostProcessorNames
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();

for (String ppName : postProcessorNames) {
    //如果已经处理了,就跳过
    if (processedBeans.contains(ppName)) {
        // skip - already processed in first phase above
    }
     //实现PriorityOrdered 接口的
    else if (isTypeMatch(ppName, PriorityOrdered.class)) {
       
        priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
    }
    // 实现Ordered 接口的
    else if (isTypeMatch(ppName, Ordered.class)) {
        orderedPostProcessorNames.add(ppName);
    }
    //普通的
    else {
        nonOrderedPostProcessorNames.add(ppName);
    }
}
  //然后先执行priorityOrderedPostProcessors中的,再执行orderedPostProcessorNames的,最后执行nonOrderedPostProcessorNames

//排序并执行priorityOrderedPostProcessors的
OrderComparator.sort(priorityOrderedPostProcessors);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

// 排序并执行orderedPostProcessors的
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : orderedPostProcessorNames) {
    orderedPostProcessors.add(getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
OrderComparator.sort(orderedPostProcessors);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

// 最后执行普通的BeanFactoryPostProcessor的
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : nonOrderedPostProcessorNames) {
    nonOrderedPostProcessors.add(getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);

}

6.registerBeanPostProcessors
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 获取IOC中注册的 BeanPostProcessor
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);

// BeanPostProcessorChecker 也是一个 BeanPostProcessor,用于检查一个Bean应该经过的BeanPostProcessor和

int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

//按照排序接口分类。
//这里需要注意的是,priorityOrderedPostProcessors里面装的是BeanPostProcessor
//而orderedPostProcessorNames和nonOrderedPostProcessorNames里面装的是BeanPostProcessor的name
//原因是:实例化BeanPostProcessor实现类的时候,也需要调用IOC中已有的BeanPostProcessor,所以Spring这里没有提前实例化Orderd接口和普通的BeanPostProcessor。
//因此,这里有一个有趣的现象,示例化Orderd接口的BeanProcessor的时候,会使用PriorityOrdered的BeanPostProcessor进行处理
//实例化普通的BeanProcessor时,会先后经过PriorityOrdered和Orderd接口的BeanPostProcessor的处理

List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();

List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();

//分类
for (String ppName : postProcessorNames) {
    //PriorityOrdered接口的,先行实例化,并把MergedBeanDefinitionPostProcessor放入到internalPostProcessors中
    if (isTypeMatch(ppName, PriorityOrdered.class)) {
        BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
        priorityOrderedPostProcessors.add(pp);
        //
        if (pp instanceof MergedBeanDefinitionPostProcessor) {
            internalPostProcessors.add(pp);
        }
    }
    //Ordered接口的,这里只是把name记录下来。
    else if (isTypeMatch(ppName, Ordered.class)) {
        //
        orderedPostProcessorNames.add(ppName);
    }
    //普通的,这里只是把name记录下来。
    else {
        nonOrderedPostProcessorNames.add(ppName);
    }
}

//排序并注册PriorityOrdered接口的BeanPostProcessor
OrderComparator.sort(priorityOrderedPostProcessors);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

//排序并注册Ordered接口的BeanPostProcessor
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : orderedPostProcessorNames) {
    //这里才进行实例化,所以会使用实现了PriorityOrdered接口的BeanPostProcessor进行处理
    BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
    orderedPostProcessors.add(pp);
    //把MergedBeanDefinitionPostProcessor放入到internalPostProcessors中
    if (pp instanceof MergedBeanDefinitionPostProcessor) {
        internalPostProcessors.add(pp);
    }
}
OrderComparator.sort(orderedPostProcessors);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);

// 注册普通的BeanPostProcessor
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : nonOrderedPostProcessorNames) {
   //这里才进行实例化,所以会使用实现了PriorityOrdered接口或Orderd的BeanPostProcessor进行处理
    BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
    nonOrderedPostProcessors.add(pp);
     //把 MergedBeanDefinitionPostProcessor 放入到internalPostProcessors中
    //同时注意到,即使在internalPostProcessors中
    //BeanPostProcessor的顺序也是按照 PriorityOrderd > Orderd > 普通 的顺序进入的。
    if (pp instanceof MergedBeanDefinitionPostProcessor) {
        internalPostProcessors.add(pp);
    }
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);

//注册所有的MergedBeanDefinitionPostProcessor
OrderComparator.sort(internalPostProcessors);
registerBeanPostProcessors(beanFactory, internalPostProcessors);

//最后,在末尾添加一个ApplicationListenerDetector
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector());

}

7.initMessageSource
初始化MessageSource组件(做国际化功能;消息绑定,消息解析);

获取BeanFactory
判断容器中是否有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: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;
将创建完成的MessageSource注册在容器中,以后获取国际化配置文件的值的时候,可以自动注入MessageSource;
protected void initMessageSource() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
// Make MessageSource aware of parent MessageSource.
//如果已经注册了 messageSource && messageSource是HierarchicalMessageSource && messageSource没有parent && 此IOC有parent
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 + “]”);
}
}
//如果没有注册messageSource,就创建一个DelegatingMessageSource,并注册到IOC中
else {
// Use empty MessageSource to be able to accept getMessage calls.
DelegatingMessageSource dms = new DelegatingMessageSource();
dms.setParentMessageSource(getInternalParentMessageSource());
this.messageSource = dms;
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.initApplicationEventMulticaster
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//如果有开发自定的applicationEventMulticaster实例bean,则设置IOC的事件广播器为该实例
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
this.applicationEventMulticaster =
beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
if (logger.isDebugEnabled()) {
logger.debug(“Using ApplicationEventMulticaster [” + this.applicationEventMulticaster + “]”);
}
}
//如果没有applicationEventMulticaster,就设置一个SimpleApplicationEventMulticaster
else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
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
模板设计模式;该方法属于钩子方法;子类重写该方法并在容器刷新的时候自定义逻辑;

protected void onRefresh() throws BeansException {
// For subclasses: do nothing by default.
}

10.registerListeners
注册监听器分为两部分:

向事件分发器注册硬编码设置的applicationListener
向事件分发器注册一个IOC中的事件监听器(并不实例化)
protected void registerListeners() {
// 查出所有通过addApplicationListener方法添加的ApplicationListener,然后注册到事件广播器上
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}

// 查出ioc容器中的所有ApplicationListener,只把他们注册到事件分发器的ApplicationListenerBean上,
// 待使用时再进行实例化
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
    getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}

}

11.finishBeanFactoryInitialization
finishBeanFactoryInitialization主要是负责初始化单实例的bean;该方法是重点方法,bean的生命周期基本调用getBean()方法完成。

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
//如果IOC中有conversionService的话,就实例化并设置到IOC中
//conversionService用于类型转换
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));
}
// 如果有LoadTimeWeaverAware,就实例化
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// 清理临时的classLoader
beanFactory.setTempClassLoader(null);
// 缓存所有beanDefinition的name,以备不时之需
beanFactory.freezeConfiguration();
// 实例化所有非non-lazy-init的单例
beanFactory.preInstantiateSingletons();
}

12.finishRefresh
完成bean创建和初始化过程,通知生命周期处理器 lifecycleProcessor 刷新过程,同时发出 ContextRefreshEvent 通知。

protected void finishRefresh() {
// 实例化或初始化lifecycleProcessor
initLifecycleProcessor();
// 调用lifecycleProcessor的刷新方法
getLifecycleProcessor().onRefresh();
//发布一个ContextRefreshedEvent事件
publishEvent(new ContextRefreshedEvent(this));
// 注册MBean,用于JMX管理
LiveBeansView.registerApplicationContext(this);
}

参考资料:

解读Spring容器的refresh()
Spring 源码深度解析
Spring IoC之ApplicationContext中refresh过程

原文链接:https://blog.youkuaiyun.com/xuan_lu/article/details/108249324?utm_medium=distribute.pc_feed.none-task-blog-personrec_tag-12.nonecase&depth_1-utm_source=distribute.pc_feed.none-task-blog-personrec_tag-12.nonecase&request_id=5f4727690388ae0b5643da4b

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