Spring源码解析——初始化解析
前言
1：实例化一个ApplicationContext的对象；
2：调用bean工厂后置处理器完成扫描；
3：循环解析扫描出来的类信息；
4：实例化一个BeanDefinition对象来存储解析出来的信息；
5：把实例化好的beanDefinition对象put到beanDefinitionMap当中缓存起来，以便后面实例化bean；
6：再次调用bean工厂后置处理器；
7：当然spring还会干很多事情，比如国际化，比如注册BeanPostProcessor等等，如果我们只关心如何实例化一个bean的话那么这一步就是spring调用finishBeanFactoryInitialization方法来实例化单例的bean，实例化之前spring要做验证，需要遍历所有扫描出来的类，依次判断这个bean是否Lazy，是否prototype，是否abstract等等；
源码
由AnnotationConfigApplicationContext入手
public class Test {
public static void main(String[] args) {
AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);
System.out.println(applicationContext.getBean("userService"));
}
}
进入AnnotationConfigApplicationContext(Class… componentClasses)
public AnnotationConfigApplicationContext(Class<?>... componentClasses) {
// 1. 创建BeanFactory
// 2. 生成AnnotatedBeanDefinitionReader
// 3. 生成ClassPathBeanDefinitionScanner
this();
// 利用reader把componentClasses注册为一个BeanDefinition
register(componentClasses);
// 调用AbstractApplicationContext的refresh()方法，模板模式，会启动ApplicationContext
// 为什么叫refresh，而不叫start?
refresh();
}
分别来分析：
- this();
主要就是初始化5个BeanDefinition，ConfigurationClassPostProcessor，AutowiredAnnotationBeanPostProcessor，CommonAnnotationBeanPostProcessor，EventListenerMethodProcessor，DefaultEventListenerFactory
public AnnotationConfigApplicationContext() {
// 在执行这个构造方法之前，会先执行父类的构造方法，会初始化一个beanFactory = new DefaultListableBeanFactory()
// 生成并注册5个BeanDefinition
// 1.ConfigurationClassPostProcessor
// 2.AutowiredAnnotationBeanPostProcessor
// 3.CommonAnnotationBeanPostProcessor
// 4.EventListenerMethodProcessor
// 5.DefaultEventListenerFactory
this.reader = new AnnotatedBeanDefinitionReader(this);
// 注册默认的includeFilter
this.scanner = new ClassPathBeanDefinitionScanner(this);
}
BeanDefinition具体生成逻辑
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
BeanDefinitionRegistry registry, @Nullable Object source) {
DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
if (beanFactory != null) {
// 设置beanFactory的OrderComparator，为AnnotationAwareOrderComparator
// 它是一个Comparator，是一个比较器，可以用来进行排序，比如new ArrayList<>().sort(Comparator);
if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
}
// 设置自动装配候选者解析式（判断某个bean是不是可以用来进行进行自动注入）
if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
}
}
Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);
// 注册ConfigurationClassPostProcessor类型的BeanDefinition
if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册AutowiredAnnotationBeanPostProcessor类型的BeanDefinition
if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册CommonAnnotationBeanPostProcessor类型的BeanDefinition
// Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册PersistenceAnnotationBeanPostProcessor类型的BeanDefinition
// Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor.
if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition();
try {
def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
AnnotationConfigUtils.class.getClassLoader()));
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
}
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册EventListenerMethodProcessor类型的BeanDefinition
if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
}
// 注册DefaultEventListenerFactory类型的BeanDefinition
if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
}
return beanDefs;
}
- register(componentClasses);
利用reader把componentClasses注册为一个BeanDefinition
/**
* 这个方法是注册一个bean最底层的方法，参数很多
* beanClass表示bean的类型
* name表示bean的名字
* qualifiers表示资格限定器，如果某个类上没有写@Lazy注解，但是在调用registerBean方法时传递了Lazy.class，那么则达到了一样的效果
* supplier表示实例提供器，如果指定了supplier，那么bean的实例是有这个supplier生成的
* customizers表示BeanDefinition自定义器，可以通过customizers对BeanDefinition进行自定义修改
*/
private <T> void doRegisterBean(Class<T> beanClass, @Nullable String name,
@Nullable Class<? extends Annotation>[] qualifiers, @Nullable Supplier<T> supplier,
@Nullable BeanDefinitionCustomizer[] customizers) {
// 直接生成一个AnnotatedGenericBeanDefinition
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(beanClass);
// 判断当前abd是否被标注了@Conditional注解，并判断是否符合所指定的条件，如果不符合，则跳过，不进行注册
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
// 设置supplier、scope属性，以及得到beanName
abd.setInstanceSupplier(supplier);
// @Scope注解的元数据信息
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
abd.setScope(scopeMetadata.getScopeName());
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
// 获取Lazy、Primary、DependsOn、Role、Description注解信息并设置给abd
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
if (qualifiers != null) {
for (Class<? extends Annotation> qualifier : qualifiers) {
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
else {
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
// 使用自定义器修改BeanDefinition
if (customizers != null) {
for (BeanDefinitionCustomizer customizer : customizers) {
customizer.customize(abd);
}
}
// BeanDefinition中是没有beanName的，BeanDefinitionHolder中持有了BeanDefinition,beanName,alias
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
// 解析Scope中的ProxyMode属性，默认为no，不生成代理对象
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
// 注册到registry中
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
- refresh();
调用AbstractApplicationContext的refresh()方法，模板模式，会启动ApplicationContext，在这里我们主要关注一个方法invokeBeanFactoryPostProcessors
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
// 刷新BeanFactory，得到一个空的BeanFactory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
// 准备BeanFactory
// 1. 设置BeanFactory的类加载器、表达式解析器、类型转化注册器
// 2. 添加三个BeanPostProcessor，注意是具体的BeanPostProcessor实例对象
// 3. 记录ignoreDependencyInterface
// 4. 记录ResolvableDependency
// 5. 添加三个单例Bean
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
// 子类可以对BeanFactory进行进一步初始化
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
// BeanFactory准备好了之后，执行BeanFactoryPostProcessor，开始对BeanFactory进行处理
// 默认情况下:
// 此时beanFactory的beanDefinitionMap中有6个BeanDefinition，5个基础BeanDefinition+AppConfig的BeanDefinition
// 而这6个中只有一个BeanFactoryPostProcessor：ConfigurationClassPostProcessor
// 这里会执行ConfigurationClassPostProcessor进行@Component的扫描，扫描得到BeanDefinition，并注册到beanFactory中
// 注意：扫描的过程中可能又会扫描出其他的BeanFactoryPostProcessor，那么这些BeanFactoryPostProcessor也得在这一步执行
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
// 从BeanFactory找出扫描得到得BeanPostProcessor，实例化并注册到BeanFactory中
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
// 初始化MessageSource，如果配置了一个名字叫做“messageSource”的BeanDefinition
// 就会把这个Bean创建出来，并赋值给ApplicationContext的messageSource属性
// 这样ApplicationContext就可以使用国际化的功能了
initMessageSource();
// Initialize event multicaster for this context.
// 设置ApplicationContext的applicationEventMulticaster
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
// 执行子类的onRefresh方法
onRefresh();
// Check for listener beans and register them.
// 注册Listener
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
// 完成beanFactory的初始化（实例化非懒加载的单例bean）
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
// 发布事件
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();
}
}
}
invokeBeanFactoryPostProcessors(beanFactory)
BeanFactory准备好了之后，执行BeanFactoryPostProcessor，开始对BeanFactory进行处理默认情况下:
此时beanFactory的beanDefinitionMap中有6个BeanDefinition，5个基础BeanDefinition+AppConfig的BeanDefinition而这6个中只有一个BeanFactoryPostProcessor：ConfigurationClassPostProcessor这里会执行ConfigurationClassPostProcessor进行@Component的扫描，扫描得到BeanDefinition，并注册到beanFactory中
注意：扫描的过程中可能又会扫描出其他的BeanFactoryPostProcessor，那么这些BeanFactoryPostProcessor也得在这一步执行
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)
// 关于LoadTimeWeaver看这篇文章了解即可，https://www.cnblogs.com/wade-luffy/p/6073702.html
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
核心invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List beanFactoryPostProcessors)
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
// 这个beanFactoryPostProcessors集合一般情况下都是空的，除非我们手动调用容器的addBeanFactoryPostProcessor方法
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
// BeanDefinitionRegistryPostProcessor是一个特殊的BeanFactoryPostProcessor，需要先执行postProcessBeanDefinitionRegistry方法
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
// 保存当前需要执行的实现了BeanDefinitionRegistryPostProcessor接口的后置处理器
// 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.
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 首先，先执行实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
// 判断这个类是否还实现了PriorityOrdered接口
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
// 这里调用了getBean，所以生成一个BeanDefinitionRegistryPostProcessor的bean对象
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// 执行postProcessBeanDefinitionRegistry方法
//todo
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 首先，先执行实现了Ordered接口的BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法
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);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后，最后其他普通的BeanDefinitionRegistryPostProcessors的postProcessBeanDefinitionRegistry方法
boolean reiterate = true;
// 在一个BeanDefinitionRegistryPostProcessor中可以注册另一个BeanDefinitionRegistryPostProcessor，所以需要递归找出所有的BeanDefinitionRegistryPostProcessor
// 一个没有实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor如果在内部注册了一个实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessor，那么就是没有实现PriorityOrdered接口的先执行
while (reiterate) {
reiterate = false;
// 这里会再一次拿到实现了PriorityOrdered接口或Ordered接口的BeanDefinitionRegistryPostProcessor，所以需要processedBeans进行过滤
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.
// 执行完BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法后，
// 再执行BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
// 执行手动添加的非BeanDefinitionRegistryPostProcessor类型的Bean工厂后置处理器的postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// 如果beanFactory没有可以注册BeanDefinition的功能，则没有BeanDefinitionRegistryPostProcessor，则执行Bean工厂后置处理器的postProcessBeanFactory方法
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 总结一下上面的流程：
// 1. 如果beanFactory实现了BeanDefinitionRegistry接口，则表示可以通过BeanDefinitionRegistryPostProcessor接口来注册BeanDefinition
// 2. 因为现在是Spring启动过程中的比较早的阶段（还没有开始扫描@Component），所以只能获取Spring默认添加到BeanFactory中的bean工厂后置处理器，以及程序员手动添加的bean工厂后置处理器
// 3. 执行的顺序是，先执行BeanDefinitionRegistryPostProcessor中的postProcessBeanDefinitionRegistry方法，因为这个方法可以注册BeanDefinition
// 4. 先执行手动添加进行来的BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法,这个过程中可能会向BeanFactory中注册其他的BeanDefinitionRegistryPostProcessor
// 5. 从BeanFactory中获取PriorityOrdered接口的BeanDefinitionRegistryPostProcessor，并执行postProcessBeanDefinitionRegistry方法
// 6. 从BeanFactory中获取Ordered接口的BeanDefinitionRegistryPostProcessor，并执行postProcessBeanDefinitionRegistry方法
// 7. 在5,6步中都有可能注册新的BeanDefinitionRegistryPostProcessor的
// 8. 从BeanFactory中获取普通的BeanDefinitionRegistryPostProcessor，并执行postProcessBeanDefinitionRegistry方法
// 9. 在8步中也有可能注册新的BeanDefinitionRegistryPostProcessor，所以第8步会递归，直到没有新的BeanDefinitionRegistryPostProcessor注册进来了
// 10. 在前面的步骤中都是执行BeanDefinitionRegistryPostProcessor中的postProcessBeanDefinitionRegistry方法，进行BeanDefinition的注册
// 11. BeanDefinition注册完了之后，因为BeanDefinitionRegistryPostProcessor本身也是一个BeanFactoryProcessor，所以最后再执行postProcessBeanFactory方法
// 12. 总结一句话就是：先通过BeanDefinitionRegistryPostProcessor注册BeanDefinition，再执行BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法
// 在默认情况下，上面的步骤中只有一个BeanDefinitionRegistryPostProcessor会执行，就是ConfigurationClassPostProcessor，因为它是Spring默认在添加进去的
// BeanDefinitionRegistryPostProcessor是特殊的BeanFactoryPostProcessor，在上面的逻辑中都处理完了
// 所以接下来就是处理普通的BeanFactoryPostProcessor
// 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);
// 默认情况下会拿到两个，一个就是ConfigurationClassPostProcessor，一个就是EventListenerMethodProcessor
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
// 保存直接实现了BeanFactoryPostProcessor接口和PriorityOrdered接口的后置处理器
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
// 保存直接实现了BeanFactoryPostProcessor接口和Ordered接口的后置处理器
List<String> orderedPostProcessorNames = new ArrayList<>();
// 保存直接实现了BeanFactoryPostProcessor接口的后置处理器，不包括那些实现了排序接口的类
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
// 把所有BeanFactoryPostProcessor进行分类
for (String ppName : postProcessorNames) {
// 拿到的BeanFactoryPostProcessor包括了BeanDefinitionRegistryPostProcessor，所以要跳过
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.
// 先执行实现了PriorityOrdered接口的BeanFactoryPostProcessor
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
// 再执行实现了Ordered接口的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
// 最后执行普通的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String postProcessorName : nonOrderedPostProcessorNames) {
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// 到此，所有的BeanFactoryPostProcessor都执行完了
// 对于BeanFactoryPostProcessor我们可以这么理解：它是去完善BeanFactory的，比如向BeanFactory中去注册BeanDefinition
// 就好比：BeanFactory是一张白纸，每个BeanFactoryPostProcessor都去这张白纸上去画上一笔，这个白纸就丰满了
// 所以这段代码，虽然内容很多，但是在默认情况下，主要就是执行了ConfigurationClassPostProcessor
// 1. 先执行了ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry方法，基本上就是去注册BeanDefinition
// 2. 然后执行了ConfigurationClassPostProcessor的postProcessBeanFactory方法
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
beanFactory.clearMetadataCache();
}
先看解析接口invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry)底层调用的postProcessBeanDefinitionRegistry，parse
/**
* Derive further bean definitions from the configuration classes in the registry.
* 扫描，得到BeanDefinition，然后注册到registry中（就是BeanFactory中）
*/
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
//生成唯一标识，用于重复处理验证
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);
// 寻找配置类对应的BeanDefinition然后进行处理
// 比如开始扫描
processConfigBeanDefinitions(registry);
}
进入processConfigBeanDefinitions(registry)处理逻辑：主要关注的方法checkConfigurationClassCandidate，
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
String[] candidateNames = registry.getBeanDefinitionNames();
// 遍历BeanDefinitionRegistry中当前存在的beanDefinition，从中找出那些beanDefinition是配置bean
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
if (beanDef.getAttribute(ConfigurationClassUtils.CONFIGURATION_CLASS_ATTRIBUTE) != null) {
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
// 检查BeanDefinition是不是配置类候选者，那么什么样的BeanDefinition符合呢？
// 1. 存在@Configuration的就是配置类，或者
// 2. 存在@Component，@ComponentScan，@Import，@ImportResource，或者
// 3. 存在@Bean标注的方法
else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// Return immediately if no @Configuration classes were found
// 没有找到配置类
if (configCandidates.isEmpty()) {
return;
}
// Sort by previously determined @Order value, if applicable
// 将配置类进行排序，根据@Order注解进行排序
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
SingletonBeanRegistry sbr = null;
// 当前BeanFactory是不是支持单例bean，如果支持则设置一个BeanNameGenerator，用来在扫描@Component和@Import某个Bean时取名字
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet) {
// 程序员可以指定一个beanName生成器 applicationContext.setBeanNameGenerator()
BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(
AnnotationConfigUtils.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
// 配置bean解析器，在解析器里存在registry，所以在解析的过程中可以往registry中添加beanDefinition
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 {
// 对配置类进行解析
parser.parse(candidates);
//主要校验配置类不能使用final修饰符（CGLIB代理是生成一个子类，因此原先的类不能使用final修饰）
parser.validate();
//排除已处理过的配置类
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());
}
// 利用reader解析ConfigurationClass，同时注册BeanDefinition
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 && !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();
}
}
checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)检查BeanDefinition是不是配置类候选者
public static boolean checkConfigurationClassCandidate(
BeanDefinition beanDef, MetadataReaderFactory metadataReaderFactory) {
String className = beanDef.getBeanClassName();
if (className == null || beanDef.getFactoryMethodName() != null) {
return false;
}
// 如果是AnnotatedBeanDefinition，那么就直接获取Metadata
// 如果是其他的，那么则根据类解析出来Metadata
AnnotationMetadata metadata;
if (beanDef instanceof AnnotatedBeanDefinition &&
className.equals(((AnnotatedBeanDefinition) beanDef).getMetadata().getClassName())) {
// Can reuse the pre-parsed metadata from the given BeanDefinition...
metadata = ((AnnotatedBeanDefinition) beanDef).getMetadata();
}
else if (beanDef instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) beanDef).hasBeanClass()) {
// Check already loaded Class if present...
// since we possibly can't even load the class file for this Class.
Class<?> beanClass = ((AbstractBeanDefinition) beanDef).getBeanClass();
if (BeanFactoryPostProcessor.class.isAssignableFrom(beanClass) ||
BeanPostProcessor.class.isAssignableFrom(beanClass) ||
AopInfrastructureBean.class.isAssignableFrom(beanClass) ||
EventListenerFactory.class.isAssignableFrom(beanClass)) {
return false;
}
metadata = AnnotationMetadata.introspect(beanClass);
}
else {
try {
MetadataReader metadataReader = metadataReaderFactory.getMetadataReader(className);
metadata = metadataReader.getAnnotationMetadata();
}
catch (IOException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Could not find class file for introspecting configuration annotations: " +
className, ex);
}
return false;
}
}
// 获取Configuration注解的属性信息，配置类分两种，被@Configuration标记的配置类为full,其他的配置类为lite,full的配置类会生成代理对象
Map<String, Object> config = metadata.getAnnotationAttributes(Configuration.class.getName());
if (config != null && !Boolean.FALSE.equals(config.get("proxyBeanMethods"))) {
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL);
}
// 注意isConfigurationCandidate方法，会检查是否存在@Component， @ComponentScan，@Import，@ImportResource，@Bean注解
else if (config != null || isConfigurationCandidate(metadata)) {
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE);
}
else {
// 如果没有Configuration注解信息，则返回false，表示不是一个配置类
return false;
}
// It's a full or lite configuration candidate... Let's determine the order value, if any.
Integer order = getOrder(metadata);
if (order != null) {
beanDef.setAttribute(ORDER_ATTRIBUTE, order);
}
return true;
}
解析Java配置类parser.parse(candidates)
parser.parse(candidates)方法最终调用processConfigurationClass方法来处理@Configuration配置类，ConfigurationClassParser. processConfigurationClass()方法实现代码如下：
// 解析配置类
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
//判断是否需要解析
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
//判断同一个配置类是否重复加载过，如果重复加载过，则合并，否则从集合中移除旧的配置类，后续逻辑将处理新的配置类
ConfigurationClass existingClass = this.configurationClasses.get(configClass);
if (existingClass != null) {
if (configClass.isImported()) {
if (existingClass.isImported()) {
existingClass.mergeImportedBy(configClass);
}
// Otherwise ignore new imported config class; existing non-imported class overrides it.
return;
}
else {
// Explicit bean definition found, probably replacing an import.
// Let's remove the old one and go with the new one.
this.configurationClasses.remove(configClass);
this.knownSuperclasses.values().removeIf(configClass::equals);
}
}
// Recursively process the configuration class and its superclass hierarchy.
SourceClass sourceClass = asSourceClass(configClass);
do {
//真正解析配置类
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
this.configurationClasses.put(configClass, configClass);
}
doProcessConfigurationClass方法主要实现从配置类中解析所有bean，包括处理内部类，父类以及各种注解
ConfigurationClassParser. doProcessConfigurationClass()解析配置类逻辑如下
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
throws IOException {
// 1. 如果配置bean上有@Component注解，递归去解析内部类上的注解
if (configClass.getMetadata().isAnnotated(Component.class.getName())) {
// Recursively process any member (nested) classes first
processMemberClasses(configClass, sourceClass);
}
// Process any @PropertySource annotations
// 2. 解析@PropertySource注解
for (AnnotationAttributes propertySource : AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), PropertySources.class,
org.springframework.context.annotation.PropertySource.class)) {
if (this.environment instanceof ConfigurableEnvironment) {
processPropertySource(propertySource);
}
else {
logger.info("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() +
"]. Reason: Environment must implement ConfigurableEnvironment");
}
}
// Process any @ComponentScan annotations
// 3. 解析@ComponentScan注解，并进行扫描
Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() &&
!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
for (AnnotationAttributes componentScan : componentScans) {
// The config class is annotated with @ComponentScan -> perform the scan immediately
// 扫描得到BeanDefinition
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
// Check the set of scanned definitions for any further config classes and parse recursively if needed
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
if (bdCand == null) {
bdCand = holder.getBeanDefinition();
}
// 检查扫描所得到BeanDefinition是不是配置Bean，基本上都有@Component注解，所以都是配置类
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
// Process any @Import annotations
// 4. 解析@Import，getImports方法返回AppConfig.class上定义的Import注解中所导入的类的信息
processImports(configClass, sourceClass, getImports(sourceClass), true);
// Process any @ImportResource annotations
// 5. 解析@ImportResource，得到导入进来的spring的xml配置文件，然后解析
AnnotationAttributes importResource =
AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
if (importResource != null) {
String[] resources = importResource.getStringArray("locations");
Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
for (String resource : resources) {
String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
configClass.addImportedResource(resolvedResource, readerClass);
}
}
// Process individual @Bean methods
// 6. 解析配置类中的加了@Bean注解的方法
Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
// Process default methods on interfaces
// 7. 如果配置类实现了某个接口，那么则解析该接口中的加了@Bean注解的默认方法
processInterfaces(configClass, sourceClass);
// Process superclass, if any
// 8. 如果有父类，则返回父类给上层遍历进行处理
if (sourceClass.getMetadata().hasSuperClass()) {
String superclass = sourceClass.getMetadata().getSuperClassName();
if (superclass != null && !superclass.startsWith("java") &&
!this.knownSuperclasses.containsKey(superclass)) {
this.knownSuperclasses.put(superclass, configClass);
// Superclass found, return its annotation metadata and recurse
return sourceClass.getSuperClass();
}
}
// No superclass -> processing is complete
return null;
}
下面分开看看@ComponentScan注解的解析过程
@ComponentScan注解解析过程：
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);
// 设置BeanName生成器
Class<? extends BeanNameGenerator> generatorClass = componentScan.getClass("nameGenerator");
boolean useInheritedGenerator = (BeanNameGenerator.class == generatorClass);
scanner.setBeanNameGenerator(useInheritedGenerator ? this.beanNameGenerator :
BeanUtils.instantiateClass(generatorClass));
ScopedProxyMode scopedProxyMode = componentScan.getEnum("scopedProxy");
if (scopedProxyMode != ScopedProxyMode.DEFAULT) {
scanner.setScopedProxyMode(scopedProxyMode);
}
else {
Class<? extends ScopeMetadataResolver> resolverClass = componentScan.getClass("scopeResolver");
scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
}
scanner.setResourcePattern(componentScan.getString("resourcePattern"));
// 设置IncludeFilter
for (AnnotationAttributes filter : componentScan.getAnnotationArray("includeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addIncludeFilter(typeFilter);
}
}
// 设置ExcludeFilter
for (AnnotationAttributes filter : componentScan.getAnnotationArray("excludeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addExcludeFilter(typeFilter);
}
}
// 设置懒加载
boolean lazyInit = componentScan.getBoolean("lazyInit");
if (lazyInit) {
scanner.getBeanDefinitionDefaults().setLazyInit(true);
}
Set<String> basePackages = new LinkedHashSet<>();
String[] basePackagesArray = componentScan.getStringArray("basePackages");
for (String pkg : basePackagesArray) {
String[] tokenized = StringUtils.tokenizeToStringArray(this.environment.resolvePlaceholders(pkg),
ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
Collections.addAll(basePackages, tokenized);
}
for (Class<?> clazz : componentScan.getClassArray("basePackageClasses")) {
basePackages.add(ClassUtils.getPackageName(clazz));
}
if (basePackages.isEmpty()) {
basePackages.add(ClassUtils.getPackageName(declaringClass));
}
scanner.addExcludeFilter(new AbstractTypeHierarchyTraversingFilter(false, false) {
@Override
protected boolean matchClassName(String className) {
return declaringClass.equals(className);
}
});
// 开始扫描包路径，得到BeanDefinitionHolder
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
scanner.doScan(StringUtils.toStringArray(basePackages))真正的处理
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
// 这是Spring中的Assert，大家开发时也可以用
Assert.notEmpty(basePackages, "At least one base package must be specified");
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
for (String basePackage : basePackages) {
// 扫描包路径得到BeanDefinition，得到的BeanDefinition是空的，还没有解析类上所定义的注解信息
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
for (BeanDefinition candidate : candidates) {
// 得到Scope的信息，并设置
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
// 得到beanName
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
//通用注解解析到candidate结构中，主要是处理Lazy, primary DependsOn, Role ,Description这五个注解
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
if (candidate instanceof AnnotatedBeanDefinition) {
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
if (checkCandidate(beanName, candidate)) {
// 生成BeanDefinitionHolder并注册到registry中
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
beanDefinitions.add(definitionHolder);
// 注册到ioc容器中，主要是一些@Component组件，@Bean注解方法并没有在此处注册， definitionHolder: beanname和beandefinition 键值对
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
findCandidateComponents(basePackage)扫描包路径得到BeanDefinition，得到的BeanDefinition是空的，还没有解析类上所定义的注解信息
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
// 扫描Component，最笨的方法就是扫描basePackage下的所有类，看是否有@Component注解
// Spring提供了一种支持更快速扫描的机制，就是编译时直接创建一个静态的
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
else {
return scanCandidateComponents(basePackage);
}
}
scanCandidateComponents(basePackage)
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
// 扫描类，得到BeanDefinition
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
if (resource.isReadable()) {
try {
// MetadataReader包含了对应class的元信息以及注解元信息, MetadataReader
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
// 判断一个类是不是Component
if (isCandidateComponent(metadataReader)) {
// 通过扫描@Component得到的BeanDefinition为ScannedGenericBeanDefinition
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
// 再进一步验证是不是备选的Component
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
candidates.add(sbd);
}
else {
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + resource);
}
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not matching any filter: " + resource);
}
}
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not readable: " + resource);
}
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
配置解析完成就得进去加载回到ConfigurationClassPostProcessor类的processConfigBeanDefinitions方法，关注this.reader.loadBeanDefinitions(configClasses);
ConfigurationClassBeanDefinitionReader.loadBeanDefinitions()方法的功能就是将之前解析出的configClasses配置类信息中所有配置相关的信息添加到spring的bean定义，主要是配置类中的@Bean注解方法，配置类@ImportResource和@Import(实现ImportBeanDefinitionRegistrar接口方式)的bean注册
public void loadBeanDefinitions(Set<ConfigurationClass> configurationModel) {
TrackedConditionEvaluator trackedConditionEvaluator = new TrackedConditionEvaluator();
for (ConfigurationClass configClass : configurationModel) {
loadBeanDefinitionsForConfigurationClass(configClass, trackedConditionEvaluator);
}
}
private void loadBeanDefinitionsForConfigurationClass(
ConfigurationClass configClass, TrackedConditionEvaluator trackedConditionEvaluator) {
if (trackedConditionEvaluator.shouldSkip(configClass)) {
String beanName = configClass.getBeanName();
if (StringUtils.hasLength(beanName) && this.registry.containsBeanDefinition(beanName)) {
this.registry.removeBeanDefinition(beanName);
}
this.importRegistry.removeImportingClass(configClass.getMetadata().getClassName());
return;
}
// 当前配置类是不是通过@Import注解导入进来的，如果是则解析该类上面的比如@Scope,@Lazy这些注解信息
if (configClass.isImported()) {
registerBeanDefinitionForImportedConfigurationClass(configClass);
}
for (BeanMethod beanMethod : configClass.getBeanMethods()) {
loadBeanDefinitionsForBeanMethod(beanMethod);
}
// 从配置类中Import进来的资源文件中加载BeanDefinition，比如xml文件
loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
// 调用ImportBeanDefinitionRegistrar对象的registerBeanDefinitions方法加载BeanDefinition
loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
}