Springboot浅析（三）——容器刷新流程
(二)BeanDefinitionRegistryPostProcessor——bean定义注册表后置处理
BeanFactoryPostProcessor的子接口，多了一个postProcessBeanDefinitionRegistry方法，这个方法允许在Bean实例化之前对BeanDefinitionRegistry（bean定义注册表）进行后置处理。
(三)BeanPostProcessor——bean后置处理器
提供对实例化后的bean进行后置处理的扩展点。一般用于对将要实例化到容器的bean进行再次加工。
(四)MergedBeanDefinitionPostProcessor——合并Bean定义后置处理器
BeanPostProcessor的子接口，多一个postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) 方法，用于后置处理合并Bean定义。
二、容器刷新流程
（一）主要代码
//最终调到AbstractApplicationContext的refresh方法public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
// 初始化前的预处理，初始化Environment里面的PropertySources(猜测是webXML里面的东西)，debug下没有什么用
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
// 获取BeanFactory,直接返回的是前面初始化的beanFactory,只不过设置了一下SerializationId
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
// 3. BeanFactory的预处理配置
//(1) 在容器注册了ApplicationContextAwareProcessor这个Bean后置处理器用于处理实现了XXXAware接口的bean，调用其setXXX方法。
//(2)忽略一些自动注入，以及添加一些自动注入的支持，为什么要忽略这些自动注入勒，因为当beanDefinition的AutowireMode为1（按setXXX方法的名称进行注入）和2（按setXXX方法返回值类型进行自动注入）时，若自动注入生效，该Bean的setXXX方法将被自动注入，那么为了避免和XXXAware接口冲突，所以进行了忽略。
//(3) 添加一些自动注入支持，包含BeanFactory，ResourceLoader，ApplicationEventPublisher，ApplicationContext。
//(4) 在容器注册了new ApplicationListenerDetector(this)这个Bean后置处理器用于收集所有实现了ApplicationListener接口的bean并收集到容器中的一个集合中。
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
// 4. 准备BeanFactory完成后进行的后置处理
//以servlet环境为例：
//(1) 添加了一个bean的后置处理器处理ServletContextAware和ServletConfigAware，用于注入ServletContext和ServletConfig。
//(2) 往容器注册Scope，Scope描述的是Spring容器如何新建Bean实例的，这里注册了Request以及Session两个Scope并且注册ServletRequest、ServletResponse、HttpSession、WebRequest为自动装配。
//(3)当判断容器的basePackages属性不为null的时候进行包扫描（但debug下这里没执行）。
//(4)当判断容器的annotatedClasses属性不为null也进行注册(debug下没执行)。
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
// 5. 执行BeanFactory创建后的后置处理器，
// 这一步里面会处理ConfigurationClassPostProcessor这个bd后置处理器完成所有的bd注册
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
// 6. 注册Bean的后置处理器
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
// 7. 初始化MessageSource
initMessageSource();
// Initialize event multicaster for this context.
// 8. 初始化事件派发器
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
// 9. 子类的多态onRefresh
onRefresh();
// Check for listener beans and register them.
// 10. 注册监听器
registerListeners();
//到此为止，BeanFactory已创建完成
// Instantiate all remaining (non-lazy-init) singletons.
// 11. 初始化所有剩下的单例Bean
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
// 12. 完成容器的创建工作
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...
// 13. 清除缓存
resetCommonCaches();
}
}
}
(二)核心点
1.prepareBeanFactory(beanFactory)-BeanFactory的预处理配置
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) { // Tell the internal bean factory to use the context"s class loader etc.
// 设置BeanFactory的类加载器、表达式解析器等
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
// 配置一个BeanPostProcessor，这个Bean后处理器将实现了以下几个Aware的bean分别回调对应的方法
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
// 配置ignoreDependencyInterface，是的这些类型自动装配无效，但实测@Autowired注入时还是能装配，故这里的意思是为了避免其他bd设置了自动注入，即AutowireMode，而不是指使用@Autowired注解进行的依赖注入。
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.
// 自动注入的支持
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.
// 配置一个可加载所有监听器的组件
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.
// 注册了默认的运行时环境、系统配置属性、系统环境的信息
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());
}
}
这里主要干了四件事：
- 在容器注册了ApplicationContextAwareProcessor这个Bean后置处理器用于处理实现了XXXAware接口的bean，调用其setXXX方法。
- 忽略一些自动注入，以及添加一些自动注入的支持，为什么要忽略这些自动注入勒，因为当beanDefinition的AutowireMode为1（按setXXX方法的名称进行注入）和2（按setXXX方法返回值类型进行自动注入）时，若自动注入生效，该Bean的setXXX方法将被自动注入，那么为了避免和XXXAware接口冲突，所以进行了忽略。
- 添加一些自动注入支持，包含BeanFactory，ResourceLoader，ApplicationEventPublisher，ApplicationContext。
- 在容器注册了new ApplicationListenerDetector(this)这个Bean后置处理器用于收集所有实现了ApplicationListener接口的bean并收集到容器中的一个集合中。
2.postProcessBeanFactory(beanFactory)-准备BeanFactory完成后进行的后置处理
以servlet为例:这里的ApplicationContext实现实际上为AnnotationConfigServletWebServerApplicationContext。在AnnotationConfigServletWebServerApplicationContext类中该方法主要是完成了：
- 往容器注册了一个bean的后置处理器处理ServletContextAware和ServletConfigAware，用于注入ServletContext和ServletConfig。
- 往容器注册Scope，Scope描述的是Spring容器如何新建Bean实例的，这里注册了Request以及Session两个Scope并且注册ServletRequest、ServletResponse、HttpSession、WebRequest为自动装配。
- 当判断容器的basePackages属性不为null的时候进行包扫描（但debug下这里没执行）。
- 当判断容器的annotatedClasses属性不为null也进行注册(debug下没执行)。
3.invokeBeanFactoryPostProcessors(beanFactory)-执行BeanFactory创建后的后置处理器
代码：
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { // 执行BeanFactory后置处理器
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()));
}
}
进入 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors())：
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
//用于存放已经执行了的processedBeans
Set<String> processedBeans = new HashSet<>();
// 这里要判断BeanFactory的类型，默认SpringBoot创建的BeanFactory是DefaultListableBeanFactory
// 这个类实现了BeanDefinitionRegistry接口，则此if结构必进
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<>();
//遍历已经注册到beanFactory的BeanFactoryPostProcessor后置处理器，然后分类为regularPostProcessors和registryProcessors
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
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.
//这个currentRegistryProcessors变量用于分阶段执行方法，因为有PriorityOrdered和Ordered接口的存在
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 首先，调用实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessors并添加到processedBeans
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);
//添加到registryProcessors
registryProcessors.addAll(currentRegistryProcessors);
//执行
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 接下来，调用实现Ordered接口的BeanDefinitionRegistryPostProcessors。
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);
}
}
//排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//添加到registryProcessors
registryProcessors.addAll(currentRegistryProcessors);
//执行
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后，调用所有其他BeanDefinitionRegistryPostProcessor
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;
}
}
//排序添加执行
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
// 回调所有BeanFactoryPostProcessor的postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
// 先回调BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法
// 再调用BeanFactoryPostProcessor的postProcessBeanFactory方法
}
// 如果BeanFactory没有实现BeanDefinitionRegistry接口，则进入下面的代码流程
else {
// Invoke factory processors registered with the context instance.
// 调用在上下文实例中注册的工厂处理器。
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 下面的部分是回调BeanFactoryPostProcessor，思路与上面的几乎一样
// 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)) {
// 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...
// 清理缓存
beanFactory.clearMetadataCache();
}
上面代码有点长主要干得事有：
- 第一步获取已经注册到容器（与beanDifinitionMap相区别，这里用了容器内beanFactoryPostProcessors这个变量存的而不是从beanDefinition获取的）的beanFactoryPostProcessor的beanFactoryPostProcessors，并筛选实现了BeanDefinitionRegistryPostProcessor接口的，执行其postProcessBeanDefinitionRegistry方法.
- 第二步获取容器内已注册的beanDefinition中BeanDefinitionRegistryPostProcessor类型的bean，筛选实现了PriorityOrdered接口的，进行排序，然后回调其postProcessBeanDefinitionRegistry。这里执行最重要的ConfigurationClassPostProcessor，他会对当前beandifinitonMap中的带有configraution注解的进行处理，比如处理@Component 、@ComponentScan 、@Import 、@ImportResource、@PropertySource 、@ComponentScan 、@Import 、@ImportResource 、@Bean注解，注册所有的beanDefinition,等一下展开讲这个ConfigurationClassPostProcessor。
- 第三步获取容器内已注册的beanDefinition中BeanDefinitionRegistryPostProcessor类型的bean，会根据是否实现PriorityOrdered接口Ordered接口进行排序（大体顺序是PriorityOrdered优先Ordered优先没实现接口的，同一接口的按方法返回值确定顺序），然后调用其postProcessBeanDefinitionRegistry方法。
- 第四步执行上面所有beanDefinitionRegistryPostProcessor类型的bean的postBeanFactory方法。
- 第五步对于ApplicationContext内（与beanDifinitionMap相区别，这里用了beanFactoryPostProcessors这个变量存而不是beanDefinition存）的beanFactoryPostProcessor，不属于BeanDefinitionRegistryPostProcessor接口的（即只是BeanFactoryProcessor），调用其postBeanFactory方法。
- 第六步调用其他所有BeanFactoryPostProcessor的postBeanFactory方法，也会解析PriorityOrdered及Ordered接口。
接下来重点看一看在第二步执行的ConfigurationClassPostProcessor的源码，内部就不详细展开了，大概的流程已经写入注释中：
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) { int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
}
if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanFactory already called on this post-processor against " + registry);
}
this.registriesPostProcessed.add(registryId);
processConfigBeanDefinitions(registry);
}
这里的意思是获取容器Id,获取其是否调用过，如果没有则继续执行processConfigBeanDefinitions。看一看 processConfigBeanDefinitions(registry)方法：
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) { List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
String[] candidateNames = registry.getBeanDefinitionNames();
// 确定配置类和组件
//带有@Configuration注解的bd的configurationClass值设为full，
//带有@Component 、@ComponentScan 、@Import 、@ImportResource注解或方法中添加了带@Bean的方法
//（只是将带bean的方法收集起来，并没有注册bd）的设为configurationClass值设为lite，并加入到configCandidates
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// Return immediately if no @Configuration classes were found
if (configCandidates.isEmpty()) {
return;
}
// Sort by previously determined @Order value, if applicable
// 对配置类进行排序
configCandidates.sort((bd1, bd2) -> {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return Integer.compare(i1, i2);
});
// Detect any custom bean name generation strategy supplied through the enclosing application context
// 加载获取BeanNameGenerator
SingletonBeanRegistry sbr = null;
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet) {
BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
if (generator != null) {
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
}
if (this.environment == null) {
this.environment = new StandardEnvironment();
}
// Parse each @Configuration class
// 初始化配置类解析器
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
//需要解析的配置类集合
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
//已经解析的配置类集合
Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
do {
// 解析配置类，最重要的方法
//对configCandidates按照@Order进行排序并遍历进行递归一直解析父类，
//需解析@PropertySource 、@ComponentScan 、@Import 、@ImportResource 、@Bean注解(注这一步还没有对扫描到的组件完全进行Bd注册，
//而只是注册了包扫描到的bd以及处理@Import注解时实现了ImportBeanDefinitionRegistrar或者ImportSelector接口的bd,
//并且这里会先处理一个类的嵌套配置类）
parser.parse(candidates);
//校验
parser.validate();
Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses());
configClasses.removeAll(alreadyParsed);
// Read the model and create bean definitions based on its content
if (this.reader == null) {
this.reader = new ConfigurationClassBeanDefinitionReader(
registry, this.sourceExtractor, this.resourceLoader, this.environment,
this.importBeanNameGenerator, parser.getImportRegistry());
}
//解析配置类中的内容
//将通过@Import、@Bean注解方式注册的类以及处理@ImportResource注解引入的配置文件解析成BeanDefinition，然后注册到BeanDefinitionMap中。
this.reader.loadBeanDefinitions(configClasses);
alreadyParsed.addAll(configClasses);
candidates.clear();
if (registry.getBeanDefinitionCount() > candidateNames.length) {
//当前的bdNames
String[] newCandidateNames = registry.getBeanDefinitionNames();
//上一次解析之前的bdNames
Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
//这次解析的bdNames
Set<String> alreadyParsedClasses = new HashSet<>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
//遍历当前bdNames，若不是以前有的，并且是配置类，并且没有被解析到，则添加到candidates，下一次循环再解析一次
for (String candidateName : newCandidateNames) {
if (!oldCandidateNames.contains(candidateName)) {
BeanDefinition bd = registry.getBeanDefinition(candidateName);
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(bd.getBeanClassName())) {
candidates.add(new BeanDefinitionHolder(bd, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
while (!candidates.isEmpty());
// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
// 将ImportRegistry注册为Bean，以支持ImportAware 和@Configuration类
if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
// 清除缓存
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
// Clear cache in externally provided MetadataReaderFactory; this is a no-op
// for a shared cache since it"ll be cleared by the ApplicationContext.
((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
}
}
4.registerBeanPostProcessors(beanFactory)-注册bean后置处理器（包含MergedBeanDefinitionPostProcessor）
注册逻辑跟注册beanFactoryPostProcessor差不多，注册顺序都会判断priorityOrdered与Ordered接口，并且先注册MergedBeanDefinitionPostProcessor再注册beanFactoryPostProcessor。
这里有两个MergedBeanDefinitionPostProcessor，一个是AutowiredAnnotationBeanPostProcessor，一个是ApplicationListenerDetector。
---------------------------- 困了，未完待续
以上是 Springboot浅析（三）——容器刷新流程 的全部内容， 来源链接： utcz.com/z/513996.html
