文章目录
- 1. refresh()概览
- 2. refresh()内部方法详解
- 2.1 prepareRefresh()
- 2.2 prepareBeanFactory(beanFactory)
- 2.3 postProcessBeanFactory(beanFactory)
- 2.4 invokeBeanFactoryPostProcessors(beanFactory)
- 2.5 registerBeanPostProcessors(beanFactory)
- 2.6 initMessageSource()
- 2.7 initApplicationEventMulticaster()
- 2.8 onRefresh()
- 2.9 registerListeners()
- 2.10 finishBeanFactoryInitialization(beanFactory)
- 2.11 finishRefresh()
上一篇文章 《spring5源码阅读(一)》中,我们分析了AnnotationConfigApplicationContext构造方法中3大方法的前两个,这一节,继续分析第3个方法refresh()。
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
//1.会首先调用父类GenericApplicationContext中的构造方法,初始化工厂bean为new DefaultListableBeanFactory()
//2.调用自己的构造方法,初始化了一个读取器:AnnotatedBeanDefinitionReader reader;一个扫描器:ClassPathBeanDefinitionScanner scanner
//3.在reader的初始化构造方法中,还注册了6个post processors
this();
//注册bean,注册就是把bean都放在某个地方,一个并发map中,Map<String, BeanDefinition> beanDefinitionMap
//这调用了AnnotatedBeanDefinitionReader reader的注册方法
register(annotatedClasses);
//实例化bean
refresh();
}
前两个方法主要实现了BeanDefinition的注册,就是放到了容器的某个map中。
第3个方法,整体上就是实现bean的实例化。包括默认后置处理器,以及的配置类(@Configuration注解修饰的),以及我们自定义的bean(加了@Componet等类似注解的)。
由于内容比较多,在这篇文章中,我们不进行过多的代码深入扩展;本篇我们只是对整体的流程有一个比较清晰的认识即可,比较深入扩展的内容,我们在其他文章中单独分析,文章连接会贴在对应的代码处。
1. refresh()概览
先看下refresh()的代码:
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
//前期准备;记录了容器启动时间;容器状态;刷新一些在此方法之前就可能已经存在的监听器
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
//最终得到DefaultListableBeanFactory,也就是在this()方法中通过父类构造函数初始化的那个bean factory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
//准备bean factory,初始化工厂的一些标准固定的容器特性
//因为后边一系列容器初始化操作,都是基于beanFactory,所以前期准备得充足
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
//空方法,用于子类扩展功能
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
//实例化并执行之前已经注册了的各种BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
//实例化 拦截bean创建的处理器BeanPostProcessor;
//这里的注册,是指把实例化的BeanPostProcessor存到beanFactory的某个list中
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
//初始化容器的MessageSource类型的bean,MessageSource用于解析消息
initMessageSource();
// Initialize event multicaster for this context.
//初始化容器的事件广播
//用于管理若干ApplicationListener对象,并向他们推送消息
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
//空方法,在特定的子类中 初始化其他特殊bean
onRefresh();
// Check for listener beans and register them.
//注册实现了ApplicationListener接口的监听者
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
//实例化剩下的单例bean,完成全部bean的实例化,除了懒加载的
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
//最后一步,完成此刷新方法,发布完成事件
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();
}
}
}
差不多有12个方法,每个方法扩展开来,可能都比较复杂,下面我们单个方法分析。
2. refresh()内部方法详解
2.1 prepareRefresh()
此方法的主要作用就是前期准备;记录了容器启动时间;容器状态;刷新一些在此方法之前就可能已经存在的监听器;初始化事件集合等。
此方法没有什么特别重要的地方,可以粗略看下,然后跳过。
protected void prepareRefresh() {
// Switch to active.
//容器启动时刻
this.startupDate = System.currentTimeMillis();
//容器激活状态,默认没有关闭
this.closed.set(false);
//容器激活状态,默认激活的
this.active.set(true);
if (logger.isInfoEnabled()) {
logger.info("Refreshing " + this);
}
// Initialize any placeholder property sources in the context environment.
//空方法
initPropertySources();
// Validate that all properties marked as required are resolvable:
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
//执行refresh之前就已经注册的listeners集合,如果没有,就初始化集合;
//调试发现是null的
if (this.earlyApplicationListeners == null) {
this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// Reset local application listeners to pre-refresh state.
//如果不为空,重新设置到applicationListeners监听器集合
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
//事件集合初始化
this.earlyApplicationEvents = new LinkedHashSet<>();
}
2.2 prepareBeanFactory(beanFactory)
准备bean factory,初始化工厂的一些标准固定的容器特性,因为后边一系列容器初始化操作,都是基于beanFactory,所以前期准备得充足。
其中入参通过以下方式得到:
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
跟代码进去,最终获取到的是获取到的是DefaultListableBeanFactory,其实在上篇中的this()中就已经初始化了。
下面看prepareBeanFactory的代码:
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
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.
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.
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
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()));
}
// Register default environment beans.
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());
}
}
都是些bean工厂本身的固有特性的初始化操作;
注意beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
这个属于神功周期中的一个环节,在初始化bean的时候,会执行。
其他也不是特别重要,看一错略看过。
2.3 postProcessBeanFactory(beanFactory)
空方法,用于子类扩展功能。
2.4 invokeBeanFactoryPostProcessors(beanFactory)
此方法比较重要;实例化并执行之前已经注册了的各种BeanFactoryPostProcessor。
BeanFactoryPostProcessor的作用就是在容器实例化具体的普通bean(比如我们自己定义的一个service类)之前,去修改(定制化)bean的相关定义。
进入方法:
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//委派模式,委派PostProcessorRegistrationDelegate类来实现具体逻辑
//getBeanFactoryPostProcessors()这里得到的是empty
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()));
}
}
核心代码在第一行,使用了委派模式;核心实现在委派类中。
我们继续进入委派类中,会发现代码比较长,主要是因为要处理不同类型的BeanFactoryPostProcessor;
但是仔细理以下,其实逻辑并不复杂,就是在查找各种BeanFactoryPostProcessor然后i将其实例化。
BeanFactoryPostProcessor总共有两种:
1.BeanFactoryPostProcessor
2.BeanDefinitionRegistryPostProcessor,它继承了第一种。
spring机制要求先处理直接实现了第二种的Post Processor,然后处理直接实现了第一种的;
在处理每一种Post Processor时,还要分优先级情况PriorityOrdered, Ordered。
整体上流程如下:
1.处理BeanDefinitionRegistryPostProcessor
-------1.1 处理PriorityOrdered优先级的
-------1.2处理Ordered优先级的
-------1.3处理其他优先级的
2.处理BeanFactoryPostProcessor
-------2.1 处理PriorityOrdered优先级的
-------2.2处理Ordered优先级的
-------2.3处理其他优先级的
由于方法代码比较长,我们从上到下拆分代码分析,一行不漏:
2.4.1 处理BeanDefinitionRegistryPostProcessor
在具体处理具体的优先级之前,先进行了如下for循环代码,这里beanFactoryPostProcessors实际默认是空的,除非手动调用AbstractApplicationContext#addBeanFactoryPostProcessor方法;因为是空的,我们暂时跳过。
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
//如果有BeanDefinitionRegistryPostProcessor类型的后置处理器,先处理这种;
//总共也就两种:
//1.BeanFactoryPostProcessor
//2.BeanDefinitionRegistryPostProcessor,它继承了第一种
//存储所有实例化的bean名字
Set<String> processedBeans = new HashSet<>();
//这里是true,因为beanFactory是DefaultListableBeanFactory,实现了BeanDefinitionRegistry
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
//常规类型的Post Processors"实例"列表,这里是相对于下一行BeanDefinitionRegistryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
//BeanDefinitionRegistry相关的Post Processors "实例"列表
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
//正常情况下,beanFactoryPostProcessors是empty;除非调用了AbstractApplicationContext#addBeanFactoryPostProcessor方法
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//遍历找到类型为BeanDefinitionRegistryPostProcessor的post processor,如果有,优先处理这个类型
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//执行后置处理方法
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
} else {
//存到list后边用
regularPostProcessors.add(postProcessor);
}
}
//后续代码在下节...
2.4.1.1 处理PriorityOrdered优先级
// 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.
//翻译上边:这里先不初始化FactoryBeans,我们需要保留所有常规bean的状态为非初始化状态,好让post-processors能对它们发挥作用
//实现了PriorityOrdered, Ordered或者其他接口的,要分开处理。
//和上边registryProcessors一样,只是这个用于暂时排序用,排完序就清空
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
//1.首先,执行实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessors,这种类型的优先级最高
//1.1 先找到beanName,就是从beanFactory中get出来
//之前在this方法中,注册了6个 post processor,第一个就是ConfigurationClassPostProcessor,它实现了PriorityOrdered接口
//所以这里数组长度是1
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//1.2 遍历beanName,实例化
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
//beanFactory是DefaultListableBeanFactory
//getBean是其父类AbstractBeanFactory中的方法,调用完getBean就完成了实例化
//这里beanFactory.getBean方法是个比较重要的方法
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//根据优先级顺序排序,每个post processor 里面都有个gerOrder指定了order的值
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
//1.3 执行后置处理方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
//这一小波处理完了,清空
currentRegistryProcessors.clear();
//后续代码在下节...
步骤说明:
1.先从beanFactory(容器)中查询到所有BeanDefinitionRegistryPostProcessor类型的bean名字。这个是很容易get到的,我们不展开了。因为在上篇文章中,已经把所有bean的定义和名字都注册到了容器中,要么存在map中,要么存在list中。
2.遍历这些名字,并判断有没有实现PriorityOrdered接口,没实现的不处理;
3.如果就是我们找的PriorityOrdered类型的,那么就通过beanFactory.getBean方法实例化bean;这个beanFactory.getBean因为代码比较多,我们单独放在下篇文章中分析《spring5源码阅读(三)》,这里我们知道它能实例化bean就行。
4.把挑选出来的post processor实例列表根据order排序;每个processor都指定了order(通过内部的gerOrder方法可获取),越大优先级越低。
5.最后就是执行这这些后置处理器的内部接口方法了。当然不同的实现类有不同的实现。
通过打断点,我们可以发现,这个for循环后,有一个符合条件的post processor,他就是ConfigurationClassPostProcessor,还记得上篇文章中的this()中,我们说了注册了6个bean定义嘛,就是其中第一个。
ConfigurationClassPostProcessor的后置处理方法postProcessBeanDefinitionRegistry(),我们暂时不展开了,大致上是处理了一些@Configuration修饰的配置类,然后进一步派生其他bean定义(比如我们自定义的model,mapper啥的)。
2.4.1.2 处理Ordered优先级
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
//2.然后实例化实现了Ordered的BeanDefinitionRegistryPostProcessors
//2.1这里又重新拉取了一遍,同1.1
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//2.2 遍历beanName,实例化
for (String ppName : postProcessorNames) {
//上边已经处理了PriorityOrdered类型的,所以这里要排除掉
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();
//后续代码在下节...
步骤说明:
同上一小节逻辑,只是这一段代码处理的是实现了Ordered接口的处理器。
注意PriorityOrdered接口继承了Ordered接口。实现了PriorityOrdered的,理论上也实现了Order,也能被getBeanNamesForType出来。所以循环内部要先排除那些实现PriorityOrdered的。
2.4.1.3 处理其他剩余优先级的
上面PriorityOrdered和Ordered两种类型的处理完了,要继续处理其他剩余的。
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//3.最后实例化 剩下的,既不是PriorityOrdered类型,也不是Ordered类型的
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();
}
//后续代码在下节...
步骤和上面是一样的。
只是这里是个while循环,为啥要循环呢,因为beanFactory.getBeanNamesForType查出来的处理完毕后,在这个处理过程中,可能会有新的bean被spring发现,并注册到容器中。
最后还剩两行,也说一下:
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
这里执行postProcessBeanFactory接口中的的回调方法,因为前边子类BeanDefinitionRegistryPostProcessor接口的方法已经优先执行了,但是父类BeanFactoryPostProcessor中,也有一个接口方法,同样需要执行。
2.4.2 处理BeanFactoryPostProcessor
上一节,说的是实现了BeanFactoryPostProcessor的子类BeanDefinitionRegistryPostProcessor接口的一些后置处理器。
这一节,是处理那些直接实现BeanFactoryPostProcessor接口的后置处理器。
我们就不在继续细分小节详细说,因为整体逻辑基本和2.4.1一样。
直接贴代码吧,上边流程弄明白了的话,看这里就会发现一样的。
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
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) {
if (processedBeans.contains(ppName)) {
//前面可能已经处理过了,跳过
// 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();
}
2.5 registerBeanPostProcessors(beanFactory)
本方法作用是实例化BeanPostProcessor,然后注册到beanFactory中;
BeanPostProcessor的作用是拦截bean创建,也就是在bean实例化的时候(实例化前后),能插入一些额外的动作。
看代码:
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}
仍然是委派模式,继续进入:
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
//从beanFactory查询之前注册的BeanPostProcessor类型的bean名字
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
//实例化一个BeanPostProcessorChecker,用于记录日志信息,比如当一个bean没有被任何后置处理器处理时
//BeanPostProcessorChecker是一个内部类,实现了BeanPostProcessor接口
// 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.
//这里也分为PriorityOrdered,Ordered, and 其他 3中情况分开处理;所以先遍历一遍,把类型分开;
//遍历时候,顺便把PriorityOrdered实例化了
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
//是否框架内部使用的PostProcessor
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.
//首先注册实现了PriorityOrdered接口的,注册就是把实例化的ostProcessors放到容器的list结合中
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
//然后注册Ordered实现了Ordered接口的
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.
//最后注册其他类型的
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.
//最后注册内部类型的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).
//初始化一个类,用于监听器的探测
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
流程比较简单,
1.从beanFactory中查找到所有BeanPostProcessor类型的bean名字;
2.PriorityOrdered,Ordered, 和其他共 3中情况分开实例化化,并注册到beanFactory中,注意并没有执行回调方法。
2.6 initMessageSource()
beanFactory有一个MessageSource类型的属性,在这里初始化它;
MessageSource用于解析消息。提供了若干获取消息的方法。
protected void initMessageSource() {
//beanFactory是DefaultListableBeanFactory;
//其实这里没必要从新获取beanFactory,直接从外边传进来不是更好嘛
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//这个if进不去
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 {
// Use empty MessageSource to be able to accept getMessage calls.
//实例化DelegatingMessageSource并添加到单例池中
DelegatingMessageSource dms = new DelegatingMessageSource();
dms.setParentMessageSource(getInternalParentMessageSource());
this.messageSource = dms;
//注册到单例池singletonObjects 中
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 + "]");
}
}
}
2.7 initApplicationEventMulticaster()
初始化一个ApplicationEventMulticaster,放在beanFactory的单例池中,
用于管理ApplicationListener,默认使用SimpleApplicationEventMulticaster。
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);
if (logger.isDebugEnabled()) {
logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
}
} 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 + "]");
}
}
}
2.8 onRefresh()
空方法;
2.9 registerListeners()
2.7节实例化了一个ApplicationEventMulticaster,用于管理ApplicationListener。
这一节的方法就是往ApplicationEventMulticaster中注册,最终放在了一个set中。
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!
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...
//广播事件到对应的监听器;
//earlyApplicationEvents是在第一个方法prepareRefresh()中初始化的
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
2.10 finishBeanFactoryInitialization(beanFactory)
实例化剩下的单例bean,完成全部bean的实例化,除了懒加载的 ;
2.11 finishRefresh()
最后一步,完成此刷新方法,发布完成事件;
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.
//执行LifecycleProcessor的方法
getLifecycleProcessor().onRefresh();
// Publish the final event.
//发布完成时间给所有的监听者
publishEvent(new ContextRefreshedEvent(this));
// Participate in LiveBeansView MBean, if active.
LiveBeansView.registerApplicationContext(this);
}