本文深入剖析Spring中BeanFactoryPostProcessor的执行流程，包括invokeBeanFactoryPostProcessors方法、BeanFactoryPostProcessor接口及其实现类的作用，以及ConfigurationClassPostProcessor如何解析@Configuration注解类。
目录
invokeBeanFactoryPostProcessors()
2.sortPostProcessors(currentRegistryProcessors, beanFactory) 方法
3.invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry)方法
processConfigBeanDefintions（）方法
ConfigurationClassUtils.checkConfigurationClassCandidate()；
4.invokeBeanFactoryPostProcessors（）方法
enhanceConfigurationClasses(beanFactory)方法 （ spring 对加有注解@Configuration 类的解析过程）
invokeBeanFactoryPostProcessors()
主要是对所有注册的BeanFactoryPostProcessor的Bean 进行调用；
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
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()));
}
}东方鲤鱼PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());此方法PostProcessorRegistrationDelegate . invokeBeanFactoryPostProcessors 方法 ：首先分别过滤 beanFactory 类的 beanDefinitionMap 属性中的 实现了 PriorityOrdered 接口 和 Ordered 接口 的 BeanDefinitionRegistryPostProcessor 类型的 bean 定义；根据过滤后的 postProcessor 注册相关的 bean定义，并且解析 Configuration 注解类；最后根据 postProcessor使用 CGLIB 加强 Configruation 注解的类；
其次分别过滤 beanFactory 类的 beanDefinitionMap 属性中的 实现了 PriorityOrdered 接口 和 Ordered 接口 的 BeanFactoryPostProcessor 类型的 bean 定义；最后根据 postProcessor 使用CGLIB 代理加强Configruation 注解的类；
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
// 判断是否是BeanDefinitionRegistry 的子类，方便发生转型
if (beanFactory instanceof BeanDefinitionRegistry) {
// 向上转型为 registry
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<>();
// 循环注册事件处理器
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.
//根据类 的 Class 获取 bean 的名称,用于过滤 BeanDefinitionRegistryPostProcessor类型的 bean 定义
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
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);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
//调用 实现了 PriorityOrdered 的 BeanDefinitionRegistryPostProcessors 处理器
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 执行
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// 执行注册处理器
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//
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();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 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...
beanFactory.clearMetadataCache();
}东方鲤鱼解析： 此方法主要是执行系统内的事件处理器，过滤是否实现 PriorityOrdered 接口 和 Ordered 接口；以及对注解Configruation 解析，代理增强；
BeanFactoryPostProcessor：顶级接口，允许 应用上下文 的 bean definition 的 自定义修改，上下文内置 bean 工厂 的 bean 属性值的 改写；
BeanDefinitionRegistryPostProcessor： BeanFactoryPostProcessor 的子接口，标准的 BeanFactoryPostProcessor SPI 的 扩展 ；
ConfigurationClassPostProcessor ： BeanDefinitionRegistryPostProcessor 的 唯一实现类，用于引导 @Configuration 注解的 类的 处理，当使用了 <context:annotation-config> 或者 <context:component-scan> 配置时，被默认的注册，否则，可以与 其他的 BeanFactoryPostProcessor 一起 手动声明；
1.getBeanNamesForType（） 方法
DefaultListableBeanFactory.getBeanNamesForType（） 方法 如下
@Override
public String[] getBeanNamesForType(@Nullable Class<?> type, boolean includeNonSingletons, boolean allowEagerInit) {
if (!isConfigurationFrozen() || type == null || !allowEagerInit) {
return doGetBeanNamesForType(ResolvableType.forRawClass(type), includeNonSingletons, allowEagerInit);
}
Map<Class<?>, String[]> cache =
(includeNonSingletons ? this.allBeanNamesByType : this.singletonBeanNamesByType);
String[] resolvedBeanNames = cache.get(type);
if (resolvedBeanNames != null) {
return resolvedBeanNames;
}
resolvedBeanNames = doGetBeanNamesForType(ResolvableType.forRawClass(type), includeNonSingletons, true);
if (ClassUtils.isCacheSafe(type, getBeanClassLoader())) {
cache.put(type, resolvedBeanNames);
}
return resolvedBeanNames;
}
private String[] doGetBeanNamesForType(ResolvableType type, boolean includeNonSingletons, boolean allowEagerInit) {
List<String> result = new ArrayList<>();
// 循环所有定义.
for (String beanName : this.beanDefinitionNames) {
// Only consider bean as eligible if the bean name
// is not defined as alias for some other bean.
if (!isAlias(beanName)) {
try {
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
// Only check bean definition if it is complete.
if (!mbd.isAbstract() && (allowEagerInit ||
((mbd.hasBeanClass() || !mbd.isLazyInit() || isAllowEagerClassLoading())) &&
!requiresEagerInitForType(mbd.getFactoryBeanName()))) {
// In case of FactoryBean, match object created by FactoryBean.
boolean isFactoryBean = isFactoryBean(beanName, mbd);
BeanDefinitionHolder dbd = mbd.getDecoratedDefinition();
boolean matchFound =
(allowEagerInit || !isFactoryBean ||
(dbd != null && !mbd.isLazyInit()) || containsSingleton(beanName)) &&
(includeNonSingletons ||
(dbd != null ? mbd.isSingleton() : isSingleton(beanName))) &&
isTypeMatch(beanName, type);
if (!matchFound && isFactoryBean) {
// In case of FactoryBean, try to match FactoryBean instance itself next.
beanName = FACTORY_BEAN_PREFIX + beanName;
matchFound = (includeNonSingletons || mbd.isSingleton()) && isTypeMatch(beanName, type);
}
if (matchFound) {
result.add(beanName);
}
}
}
catch (CannotLoadBeanClassException ex) {
if (allowEagerInit) {
throw ex;
}
// Probably contains a placeholder: let's ignore it for type matching purposes.
if (this.logger.isDebugEnabled()) {
this.logger.debug("Ignoring bean class loading failure for bean '" + beanName + "'", ex);
}
onSuppressedException(ex);
}
catch (BeanDefinitionStoreException ex) {
if (allowEagerInit) {
throw ex;
}
// Probably contains a placeholder: let's ignore it for type matching purposes.
if (this.logger.isDebugEnabled()) {
this.logger.debug("Ignoring unresolvable metadata in bean definition '" + beanName + "'", ex);
}
onSuppressedException(ex);
}
}
}
// 循环所有手动注册定义.
for (String beanName : this.manualSingletonNames) {
try {
// In case of FactoryBean, match object created by FactoryBean.
if (isFactoryBean(beanName)) {
if ((includeNonSingletons || isSingleton(beanName)) && isTypeMatch(beanName, type)) {
result.add(beanName);
// Match found for this bean: do not match FactoryBean itself anymore.
continue;
}
// In case of FactoryBean, try to match FactoryBean itself next.
beanName = FACTORY_BEAN_PREFIX + beanName;
}
// Match raw bean instance (might be raw FactoryBean).
if (isTypeMatch(beanName, type)) {
result.add(beanName);
}
}
catch (NoSuchBeanDefinitionException ex) {
// Shouldn't happen - probably a result of circular reference resolution...
if (logger.isDebugEnabled()) {
logger.debug("Failed to check manually registered singleton with name '" + beanName + "'", ex);
}
}
}
return StringUtils.toStringArray(result);
}东方鲤鱼
protected RootBeanDefinition getMergedBeanDefinition(
String beanName, BeanDefinition bd, @Nullable BeanDefinition containingBd)
throws BeanDefinitionStoreException {
synchronized (this.mergedBeanDefinitions) {
// 准备一个RootBeanDefinition变量引用，用于记录要构建和最终要返回的BeanDefinition，
RootBeanDefinition mbd = null;
// Check with full lock now in order to enforce the same merged instance.
if (containingBd == null) {
mbd = this.mergedBeanDefinitions.get(beanName);
}
if (mbd == null) {
// 判断当前BeanDefinition 是否有父类，如果ParentName 为null ,证明是RootBeanDefinition 类型
if (bd.getParentName() == null) {
// Use copy of given root bean definition.
if (bd instanceof RootBeanDefinition) {
mbd = ((RootBeanDefinition) bd).cloneBeanDefinition();
}
else {
mbd = new RootBeanDefinition(bd);
}
}
// 否则，当前BeanDefinition为ChildReanDefinition 类型
// 这种情况下，需要将bd和其parent bean definition 合并到一起,
// 用到了递归执行getMergedBeanDefinition，原因，当前BeanDefinition存在父类，我们进行合并，那么父类也有可能还存在父类，所以需要递归
else {
// Child bean definition: needs to be merged with parent.
// 最终形成合并后保存保存对象
BeanDefinition pbd;
try {
String parentBeanName = transformedBeanName(bd.getParentName());
if (!beanName.equals(parentBeanName)) {
pbd = getMergedBeanDefinition(parentBeanName);
}
else {
BeanFactory parent = getParentBeanFactory();
if (parent instanceof ConfigurableBeanFactory) {
pbd = ((ConfigurableBeanFactory) parent).getMergedBeanDefinition(parentBeanName);
}
else {
throw new NoSuchBeanDefinitionException(parentBeanName,
"Parent name '" + parentBeanName + "' is equal to bean name '" + beanName +
"': cannot be resolved without an AbstractBeanFactory parent");
}
}
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanDefinitionStoreException(bd.getResourceDescription(), beanName,
"Could not resolve parent bean definition '" + bd.getParentName() + "'", ex);
}
// Deep copy with overridden values.
mbd = new RootBeanDefinition(pbd);
mbd.overrideFrom(bd);
}
// Set default singleton scope, if not configured before.
if (!StringUtils.hasLength(mbd.getScope())) {
mbd.setScope(RootBeanDefinition.SCOPE_SINGLETON);
}
// A bean contained in a non-singleton bean cannot be a singleton itself.
// Let's correct this on the fly here, since this might be the result of
// parent-child merging for the outer bean, in which case the original inner bean
// definition will not have inherited the merged outer bean's singleton status.
if (containingBd != null && !containingBd.isSingleton() && mbd.isSingleton()) {
mbd.setScope(containingBd.getScope());
}
// Cache the merged bean definition for the time being
// (it might still get re-merged later on in order to pick up metadata changes)
if (containingBd == null && isCacheBeanMetadata()) {
this.mergedBeanDefinitions.put(beanName, mbd);
}
}
return mbd;
}
} 解析： 主要是对系统内部定义的bean 与我们手动注册的bean 这个个集合做循环过滤，通过beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false)，获取spring配置文件中定义的所有实现BeanFactoryPostProcessor接口的bean，然后根据优先级进行排序，之后对于每个BeanFactoryPostProcessor，调用postProcessBeanFactory方法
最终返回一个roootBeanDifinition 对象，
2.sortPostProcessors(currentRegistryProcessors, beanFactory) 方法
private static void sortPostProcessors(List<?> postProcessors, ConfigurableListableBeanFactory beanFactory) {
Comparator<Object> comparatorToUse = null;
if (beanFactory instanceof DefaultListableBeanFactory) {
comparatorToUse = ((DefaultListableBeanFactory) beanFactory).getDependencyComparator();
}
if (comparatorToUse == null) {
comparatorToUse = OrderComparator.INSTANCE;
}
Collections.sort(postProcessors, comparatorToUse);
}解析： 此方法主要是对实现了Ordered 接口的扩展类进行排序，按优先级执行；看都用的是工具类Collections.sort()方法；
3.invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry)方法
PostProcessorRegistrationDelegate . invokeBeanDefinitionRegistryPostProcessors（）方法： 处理 bean 定义的记录器
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}此处循环执行 postProcessBeanDefinitionRegistry（）方法；此方法BeanDefinitionRegistryPostProcessor . postProcessBeanDefinitionRegistry（） 为抽象方法；实现类为ConfigurationClassPostProcessor类，ConfigurationClassPostProcessor类 主要是对上下文中的beanDifinition 集合中的configuration 注解解析，查看此类方法；
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
RootBeanDefinition iabpp = new RootBeanDefinition(ConfigurationClassPostProcessor.ImportAwareBeanPostProcessor.class);
iabpp.setRole(2);
registry.registerBeanDefinition(IMPORT_AWARE_PROCESSOR_BEAN_NAME, iabpp);
RootBeanDefinition ecbpp = new RootBeanDefinition(ConfigurationClassPostProcessor.EnhancedConfigurationBeanPostProcessor.class);
ecbpp.setRole(2);
registry.registerBeanDefinition(ENHANCED_CONFIGURATION_PROCESSOR_BEAN_NAME, ecbpp);
int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException("postProcessBeanDefinitionRegistry already called for this post-processor against " + registry);
} else if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException("postProcessBeanFactory already called for this post-processor against " + registry);
} else {
this.registriesPostProcessed.add(registryId);
this.processConfigBeanDefinitions(registry);
}
}东方鲤鱼 解析：主要是最后一步 ConfigurationClassPostProcessor . processConfigBeanDefintions（）方法：创建和验证 基于 registry 的 configuration 模型；即解析 registry beanDefinitionMap 中 Configuration 注解的 类
processConfigBeanDefintions（）方法
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
String[] candidateNames = registry.getBeanDefinitionNames();
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
configCandidates.sort((bd1, bd2) -> {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return (i1 < i2) ? -1 : (i1 > i2) ? 1 : 0;
});
// Detect any custom bean name generation strategy supplied through the enclosing application context
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
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
do {
parser.parse(candidates);
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());
}
this.reader.loadBeanDefinitions(configClasses);
alreadyParsed.addAll(configClasses);
candidates.clear();
if (registry.getBeanDefinitionCount() > candidateNames.length) {
String[] newCandidateNames = registry.getBeanDefinitionNames();
Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
Set<String> alreadyParsedClasses = new HashSet<>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
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
if (sbr != null) {
if (!sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
}
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();
}
}东方鲤鱼解析： 各版本此处代码不同 ，但逻辑基本没变，作用是即解析 registry beanDefinitionMap 中 Configuration 注解的 类 ，主要类介绍一下； SingletonBeanRegistry：顶层接口，定义了一个用于 共享 bean 实例 的 registry，ConfigurableBeanFactory 接口 继承了该接口；
ConfigurationClassParser 类：用于解析 一个 Configuration 标注的 类 的 定义，得到的是一个 ConfiguraionClass 对象的集合（解析一个单独的 Configuration 类可以产生多个 ConfigurationClass 对象，因为一个 Configuration 类 可以使用 import 注解导入其他的 Configuration 类）；
ConfigurationClass：代表 用户使用 @Configuration 注解 定义 的 Cofiguration 类，包含了一组 bean 方法（@Bean 注解的方法；
ConfigurationClassUtils.checkConfigurationClassCandidate() 方法
ConfigurationClassUtils.checkConfigurationClassCandidate()；
此方法是spring 对Bean是Configaration的判断；这个方法中前半部分就是为了得到这个Bean对应的AnnotationMetadata。随后通过两个判断方法isFullConfigurationCandidate和isLiteConfigurationCandidate判断是否需要给BeanDefination中增加对应的键值对，通过setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL)或beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE);设置 full和lite属性；而key：CONFIGURATION_CLASS_ATTRIBUTE 就是 org.springframework.context.annotation.ConfigurationClassPostProcessor.configurationClass 。那么看看是具体怎么判断的：
public static boolean isFullConfigurationCandidate(AnnotationMetadata metadata) {
return metadata.isAnnotated(Configuration.class.getName());
}
public static boolean isLiteConfigurationCandidate(AnnotationMetadata metadata) {
// Do not consider an interface or an annotation...
if (metadata.isInterface()) {
return false;
}
// Any of the typical annotations found?
for (String indicator : candidateIndicators) {
if (metadata.isAnnotated(indicator)) {
return true;
}
}
// Finally, let's look for @Bean methods...
try {
return metadata.hasAnnotatedMethods(Bean.class.getName());
}
catch (Throwable ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to introspect @Bean methods on class [" + metadata.getClassName() + "]: " + ex);
}
return false;
}
}东方鲤鱼解析：如果类上有@Configuration注解说明是一个完全（Full）的配置类；
isLiteConfigurationCandidate 判断 如果是一个接口，那么不是简化（Lite）配置类，如果类上有candidateIndicators这个Set中定义的注解的话（@Component，@ComponentScan，@Import，@ImportResource）那么就是一个简化配置类，如果不是上面两种情况，那么有@Bean注解修饰的方法也是简化配置类；
candidateIndicators 为静态定义
到此 就是spring是怎么判断是一个配置类，随后将配置类放入到scannedBeanDefinitions set集合中，通过parse（） 方法将Configuration注册成了BeanDefinition,将配置文件里面的使用@Bean注释的方法变成了BeanDefinition，将ImportResource进来的配置文件加载解析，从资源文件加载合适的Bean,最后一个就是调用Config类中ImportBeanDefinitionRegistrar类型的对象的registerBeanDefinitions方法，实现他们内部的注册逻辑。
4.invokeBeanFactoryPostProcessors（）方法
private static void invokeBeanFactoryPostProcessors(
Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {
for (BeanFactoryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanFactory(beanFactory);
}
}解析：此处的BeanFactoryPostProcessor 是经过上一步过滤以后的，作用调用过滤后的处理器；
postProcessBeanFactory()方法
此方法是在BeanFactoryPostProcessor 中定义的接口，BeanFactoryPostProcessor允许在容器实例化任何其他的bean之前读取配置元数据,并有可能修改它；实现类有ConfigurationClassPostProcessor 类，查看实现方法：
Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
int factoryId = System.identityHashCode(beanFactory);
if (this.factoriesPostProcessed.contains(factoryId)) {
throw new IllegalStateException(
"postProcessBeanFactory already called on this post-processor against " + beanFactory);
}
this.factoriesPostProcessed.add(factoryId);
if (!this.registriesPostProcessed.contains(factoryId)) {
// BeanDefinitionRegistryPostProcessor hook apparently not supported...
// Simply call processConfigurationClasses lazily at this point then.
//调用processConfigurationClasses 完成上一步的注册
processConfigBeanDefinitions((BeanDefinitionRegistry) beanFactory);
}
// 对容器中的Configuration 注解的类 的 beanDefinition进行处理
enhanceConfigurationClasses(beanFactory);
beanFactory.addBeanPostProcessor(new ImportAwareBeanPostProcessor(beanFactory));
}东方鲤鱼enhanceConfigurationClasses(beanFactory)方法 （ spring 对加有注解@Configuration 类的解析过程）
此方法是spring 对加有注解@Configuration 类的解析过程；上边我们知道spring 怎么判断一个类是不是配置类；这里就是解析配置的过程；
public void enhanceConfigurationClasses(ConfigurableListableBeanFactory beanFactory) {
Map<String, AbstractBeanDefinition> configBeanDefs = new LinkedHashMap<>();
//遍历查找 beanDefinitionNames map 中的 configuration 注解类的 bean 定义
for (String beanName : beanFactory.getBeanDefinitionNames()) {
BeanDefinition beanDef = beanFactory.getBeanDefinition(beanName);
// isFullConfigurationClass 判断是否是full configuration，带有@Configuration注解的类，那么这个类叫做full configuration
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef)) {
if (!(beanDef instanceof AbstractBeanDefinition)) {
throw new BeanDefinitionStoreException("Cannot enhance @Configuration bean definition '" +
beanName + "' since it is not stored in an AbstractBeanDefinition subclass");
}
else if (logger.isWarnEnabled() && beanFactory.containsSingleton(beanName)) {
logger.warn("Cannot enhance @Configuration bean definition '" + beanName +
"' since its singleton instance has been created too early. The typical cause " +
"is a non-static @Bean method with a BeanDefinitionRegistryPostProcessor " +
"return type: Consider declaring such methods as 'static'.");
}
configBeanDefs.put(beanName, (AbstractBeanDefinition) beanDef);
}
}
if (configBeanDefs.isEmpty()) {
// nothing to enhance -> return immediately
return;
}
// 增强 Configuration 注解的 类，这里的增强就是使用代理（CGLIB）
ConfigurationClassEnhancer enhancer = new ConfigurationClassEnhancer();
for (Map.Entry<String, AbstractBeanDefinition> entry : configBeanDefs.entrySet()) {
AbstractBeanDefinition beanDef = entry.getValue();
// If a @Configuration class gets proxied, always proxy the target class
beanDef.setAttribute(AutoProxyUtils.PRESERVE_TARGET_CLASS_ATTRIBUTE, Boolean.TRUE);
try {
// Set enhanced subclass of the user-specified bean class
Class<?> configClass = beanDef.resolveBeanClass(this.beanClassLoader);
if (configClass != null) {
// 真正生成代理的过程
Class<?> enhancedClass = enhancer.enhance(configClass, this.beanClassLoader);
if (configClass != enhancedClass) {
if (logger.isDebugEnabled()) {
logger.debug(String.format("Replacing bean definition '%s' existing class '%s' with " +
"enhanced class '%s'", entry.getKey(), configClass.getName(), enhancedClass.getName()));
}
beanDef.setBeanClass(enhancedClass);
}
}
}
catch (Throwable ex) {
throw new IllegalStateException("Cannot load configuration class: " + beanDef.getBeanClassName(), ex);
}
}
}
东方鲤鱼spring 判断非接口类 默认采用cglib代理；至于spring中的代理怎么区别采用 ，后边单独写；
public Class<?> enhance(Class<?> configClass, @Nullable ClassLoader classLoader) {
if (EnhancedConfiguration.class.isAssignableFrom(configClass)) {
if (logger.isDebugEnabled()) {
logger.debug(String.format("Ignoring request to enhance %s as it has " +
"already been enhanced. This usually indicates that more than one " +
"ConfigurationClassPostProcessor has been registered (e.g. via " +
"<context:annotation-config>). This is harmless, but you may " +
"want check your configuration and remove one CCPP if possible",
configClass.getName()));
}
return configClass;
}
Class<?> enhancedClass = createClass(newEnhancer(configClass, classLoader));
if (logger.isDebugEnabled()) {
logger.debug(String.format("Successfully enhanced %s; enhanced class name is: %s",
configClass.getName(), enhancedClass.getName()));
}
return enhancedClass;
}
到此 invokeBeanFactoryPostProcessors 方法执行结束； 当然源码中有很多分支流程，我没有一一贴图，不足指出，欢迎赐教；
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