Spring IOC容器源码解析之扩展原理
知识点：spring源码解析之扩展原理BeanFactoryPostProcessor和BeanDefinitionPostProcessor和ApplicationListener
一、Spring 是如何发布事件？ApplicationListener
1、 自己写一个NiuhApplicationListener 实现 ApplicationListener，并且把该组件加到容器中
@Configuration
@ComponentScan("com.niuh")
public class MainConfig {
}
@Component
public class NiuhApplicationListener implements ApplicationListener {
// 接收到消息，回调该方法
@Override
public void onApplicationEvent(ApplicationEvent applicationEvent) {
System.out.println("NiuhApplicationListener 接收到一个事件：" + applicationEvent);
}
}
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MainConfig.class);
// 手动发布一个事件
context.publishEvent(new ApplicationEvent("我手动发布了一个事件") {
@Override
public Object getSource() {
return super.getSource();
}
});
// 容器关闭也发布事件
context.close();
}
测试结果：
NiuhApplicationListener 接收到一个事件：org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.annotation.AnnotationConfigApplicationContext@7bfcd12c: startup date [Fri Jul 05 12:58:12 CST 2019]; root of context hierarchy]
NiuhApplicationListener 接收到一个事件：com.niuh.SpringTest$1[source=我手动发布了一个事件]
NiuhApplicationListener 接收到一个事件：org.springframework.context.event.ContextClosedEvent[source=org.springframework.context.annotation.AnnotationConfigApplicationContext@7bfcd12c: startup date [Fri Jul 05 12:58:12 CST 2019]; root of context hierarchy]
源码解析：
i1>org.springframework.context.support.AbstractApplicationContext#refresh
i2 >org.springframework.context.support.AbstractApplicationContext#initApplicationEventMulticaster （初始化事件多播器）
i3 >org.springframework.context.support.AbstractApplicationContext#registerListeners （把事件监听器注册到多播器）
- i2 ：初始化事件多播器 源码解析
/**
* Initialize the ApplicationEventMulticaster.
* Uses SimpleApplicationEventMulticaster if none defined in the context.
* @see org.springframework.context.event.SimpleApplicationEventMulticaster
*/
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
// 判断IOC容器中包含applicationEventMulticaster事件多播器的Bean的name
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
// 创建一个applicationEventMulticaster 的bean放在IOC容器中，bean的name为applicationEventMulticaster
this.applicationEventMulticaster = beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
if (logger.isDebugEnabled()) {
logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
}
}
// 容器中不包含一个beanName 为applicationEventMulticaster的多播器组件
else {
// 创建一个 SimpleApplicationEventMulticaster 多播器
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
// 注册到容器中
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
if (logger.isDebugEnabled()) {
logger.debug("Unable to locate ApplicationEventMulticaster with name '" +
APPLICATION_EVENT_MULTICASTER_BEAN_NAME +
"': using default [" + this.applicationEventMulticaster + "]");
}
}
}
- i3： 把容器中的监听器注册到多播器上去 源码解析
/**
* Add beans that implement ApplicationListener as listeners.
* Doesn't affect other listeners, which can be added without being beans.
*/
protected void registerListeners() {
// Register statically specified listeners first.
// 去容器中把applicationListener捞取出来注册到多播器上去 （系统的）
for (ApplicationListener listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let post-processors apply to them!
// 我们自己实现了ApplicationListener的组件
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// Publish early application events now that we finally have a multicaster...
// 在这里之前，我们早期想发布的事件由于没有多播器没有发布，在这里我们总算有了自己的多播器，可以在这里发布早期堆积的事件了
Set earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
-------------------------------如何发布事件的--------------------------------
public void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {
ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));
// 获取到所有的监听器
for (final ApplicationListener listener : getApplicationListeners(event, type)) {
// 看spring容器中是否支持线程池，异步发送事件
Executor executor = getTaskExecutor();
if (executor != null) {
executor.execute(() -> invokeListener(listener, event));
}
else {
// 同步发送事件
invokeListener(listener, event);
}
}
}
private void doInvokeListener(ApplicationListener listener, ApplicationEvent event) {
try {
// 调用对于listener的onApplicationEvent事件
listener.onApplicationEvent(event);
}
catch (ClassCastException ex) {
String msg = ex.getMessage();
if (msg == null || matchesClassCastMessage(msg, event.getClass())) {
// Possibly a lambda-defined listener which we could not resolve the generic event type for
// -> let's suppress the exception and just log a debug message.
Log logger = LogFactory.getLog(getClass());
if (logger.isDebugEnabled()) {
logger.debug("Non-matching event type for listener: " + listener, ex);
}
}
else {
throw ex;
}
}
}
二、BeanDefinitionRegistryPostProcessor 的处理源码流程
执行时机：所有的bean定义信息将要被加载到容器中，Bean实例还没有被初始化。
@Component
public class NiuhBeanDefinationRegisterPostProcessor implements BeanDefinitionRegistryPostProcessor {
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
System.out.println("NiuhBeanDefinationRegisterPostProcessor的postProcessBeanDefinitionRegistry方法");
System.out.println("bean定义的数量：" + beanDefinitionRegistry.getBeanDefinitionCount());
RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(NiuhLog.class);
beanDefinitionRegistry.registerBeanDefinition("niuhLog",rootBeanDefinition);
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
System.out.println("NiuhBeanDefinationRegisterPostProcessor的postProcessBeanFactory方法");
System.out.println(configurableListableBeanFactory.getBeanDefinitionCount());
}
}
三、BeanFactoryPostProcessor 处理流程
执行时间：所有的Bean定义信息已经加载到容器中，但是Bean实例还没有被初始化。
@Component
public class NiuhBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("IOC容器调用了NiuhBeanFactoryPostProcessor的postProcessBeanFactory方法");
for(String name:beanFactory.getBeanDefinitionNames()) {
if("niuhLog".equals(name)) {
BeanDefinition beanDefinition = beanFactory.getBeanDefinition(name);
beanDefinition.setLazyInit(true);
}
}
}
}
调用链：
i1:org.springframework.context.support.AbstractApplicationContext#refresh
>i2:org.springframework.context.support.AbstractApplicationContext#invokeBeanFactoryPostProcessors
>i3:org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
>i4:org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanDefinitionRegistryPostProcessors
>i5:org.springframework.context.annotation.ConfigurationClassPostProcessor#processConfigBeanDefinitions
>i6:org.springframework.context.annotation.ConfigurationClassParser#parse
>i7:org.springframework.context.annotation.ConfigurationClassParser#processConfigurationClass
>i8:org.springframework.context.annotation.ConfigurationClassParser#doProcessConfigurationClass
- i3标记处源码解析 org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set processedBeans = new HashSet<>();
// 判断IOC容器是不是BeanDefinitionRegistry
if (beanFactory instanceof BeanDefinitionRegistry) {
// 把IOC容器强制转为BeanDefinitionRegistry类型的
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
// 创建一个普通的PostProcessors的list组件
List regularPostProcessors = new ArrayList<>();
// 创建一个BeanDefinitionRegistryPostProcessor类型的list
List registryProcessors = new ArrayList<>();
// 处理容器硬编码（new 出来的）带入的beanFactoryProcessor
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//判断是不是BeanDefinitionRegistryPostProcessor
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//调用BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry
registryProcessor.postProcessBeanDefinitionRegistry(registry);
//加入到list集合中ConfigurationClassPostProcessor
registryProcessors.add(registryProcessor);
}
else {//判断不是BeanDefinitionRegistryPostProcessor
//加入到集合中
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.
//创建一个当前注册的RegistryProcessors的集合
List currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 第一步:去容器中查询是否有BeanDefinitionRegistryPostProcessor类型的
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
//判断是不是实现了PriorityOrdered接口的
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
//添加到currentRegistryProcessors的集合中
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
//添加到processedBeans的集合中
processedBeans.add(ppName);
}
}
//进行排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
//调用BeanDefinitionRegistryPostProcessors的postProcessBeanDefinitionRegistry方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 第二步:去容器中查询是否有BeanDefinitionRegistryPostProcessor类型的
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
//排除被处理过的，并且实现了Ordered接口的
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
//加到以处理的list中
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
//调用BeanDefinitionRegistryPostProcessors的postProcessBeanDefinitionRegistry方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//调用普通的BeanDefinitionRegistryPostProcessors没用实现 PriorithOrdered和Ordered接口
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.
//调用上诉实现了也实现了BeanFactoryPostProcessors的接口
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!
//去IOC 容器中获取BeanFactoryPostProcessor 类型的
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
//分离实现了PriorityOrdered接口的 Ordered 接口的 普通的
List priorityOrderedPostProcessors = new ArrayList<>();
List orderedPostProcessorNames = new ArrayList<>();
List 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.
// 调用 PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
//调用 Ordered.
List 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.
//调用普通的
List 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();
}
- i5标记处源码解析，org.springframework.context.annotation.ConfigurationClassPostProcessor#processConfigBeanDefinitions
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List configCandidates = new ArrayList<>();
//没有解析之前，系统候选的bean定义配置(有自己的 有系统自带的)
String[] candidateNames = registry.getBeanDefinitionNames();
//循环Bean定义的名称 找出自己的传入的主配置类的bean定义信息 configCandidates
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
//检查该bean定义对象是不是用来描述配置类
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
//检查配置类排序
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
// bean的名称生成策略
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();
}
/***创建一个配置类解析器
1)元数据读取器工厂
this.metadataReaderFactory = metadataReaderFactory;
2)问题报告器
this.problemReporter = problemReporter;
//设置环境
this.environment = environment;
3)资源加载器
this.resourceLoader = resourceLoader;
4）创建了一个组件扫描器
this.componentScanParser = new ComponentScanAnnotationParser(
environment, resourceLoader, componentScanBeanNameGenerator, registry);
this.conditionEvaluator = new ConditionEvaluator(registry, environment, resourceLoader);
****/
// Parse each @Configuration class
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
//将要被解析的配置类(把自己的configCandidates加入到 候选的)
Set candidates = new LinkedHashSet<>(configCandidates);
//已经被解析的配置类(由于do while 那么mainclass就一定会被解析,被解析的size为1)
Set alreadyParsed = new HashSet<>(configCandidates.size());
do {
//通过配置解析器真正的解析配置类
parser.parse(candidates);
//进行校验
parser.validate();
//获取ConfigClass (把解析过的配置bean定义信息获取出来)
Set 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());
}
//@CompentScan是直接注册Bean定义信息的 但是通过获取@Import,@Bean这种的注解还没有注册的bean定义,
this.reader.loadBeanDefinitions(configClasses);
//把系统解析过我们自己的组件放在alreadyParsed
alreadyParsed.addAll(configClasses);
//清除解析过的 配置文件
candidates.clear();
//已经注册的bean定义个数大于最新 开始系统+主配置类的(发生过解析)
if (registry.getBeanDefinitionCount() > candidateNames.length) {
//获取系统+自己解析的+mainconfig的bean定义信息
String[] newCandidateNames = registry.getBeanDefinitionNames();
//系统的+mainconfig的bean定义信息
Set oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
//已经解析过的自己的组件
Set alreadyParsedClasses = new HashSet<>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
//老的（系统+mainconfig） 不包含解析的
if (!oldCandidateNames.contains(candidateName)) {
//把当前bean定义获取出来
BeanDefinition bd = registry.getBeanDefinition(candidateName);
//检查是否为解析过的
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(bd.getBeanClassName())) {
//若不是解析过且通过检查的 把当前的bean定义 加入到candidates中
candidates.add(new BeanDefinitionHolder(bd, candidateName));
}
}
}
// 把解析过的赋值给原来的
candidateNames = newCandidateNames;
}
}
while (!candidates.isEmpty()); //还存主没有解析过的 再次解析
// 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();
}
}
- i6标记处源码解析 org.springframework.context.annotation.ConfigurationClassParser#parse
public void parse(Set configCandidates) {
this.deferredImportSelectors = new LinkedList<>();
for (BeanDefinitionHolder holder : configCandidates) {
BeanDefinition bd = holder.getBeanDefinition();
try {
//注解形式的bean定义信息
if (bd instanceof AnnotatedBeanDefinition) {
//解析配置类的bean定义
parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName());
}
else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) bd).hasBeanClass()) {
parse(((AbstractBeanDefinition) bd).getBeanClass(), holder.getBeanName());
}
else {
parse(bd.getBeanClassName(), holder.getBeanName());
}
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to parse configuration class [" + bd.getBeanClassName() + "]", ex);
}
}
processDeferredImportSelectors();
}
===================================================================
>org.springframework.context.annotation.ConfigurationClassParser#parse
>org.springframework.context.annotation.ConfigurationClassParser#processConfigurationClass
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
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.
// 递归处理配置类及其超类层次结构。
SourceClass sourceClass = asSourceClass(configClass);
do {
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
this.configurationClasses.put(configClass, configClass);
}
===================================================================
>org.springframework.context.annotation.ConfigurationClassParser#doProcessConfigurationClass
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
throws IOException {
// Recursively process any member (nested) classes first
processMemberClasses(configClass, sourceClass);
// Process any @PropertySource annotations
//处理@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.warn("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() +
"]. Reason: Environment must implement ConfigurableEnvironment");
}
}
//处理@ComponentScan注解
//解析@ComponentScans注解的属性 封装成一个一个的componentscan对象
// Process any @ComponentScan annotations
Set componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() &&
!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
//循环componentScans的set
for (AnnotationAttributes componentScan : componentScans) {
// The config class is annotated with @ComponentScan -> perform the scan immediately
// 立即执行扫描解析
Set scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
// Check the set of scanned definitions for any further config classes and parse recursively if needed
//检查任何其他配置类的扫描定义集，并在需要时递归解析
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
//获取原始的bean定义信息
BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
if (bdCand == null) {
bdCand = holder.getBeanDefinition();
}
//检查当前的bean定义信息是不是配置类 比如MainConfig的bean定义信息
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
//递归调用来解析MainConfig,解析出来配置类的中导入的bean定义信息
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
//处理@Import注解 解析Import 注解的ImportSelector ImportBeanDefinitionRegister,@Bean这种
//存放在ConfigClass中
// Process any @Import annotations
processImports(configClass, sourceClass, getImports(sourceClass), true);
//处理 @ImportResource annotations
// Process any @ImportResource annotations
AnnotationAttributes importResource =
AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
if (importResource != null) {
String[] resources = importResource.getStringArray("locations");
Class readerClass = importResource.getClass("reader");
for (String resource : resources) {
String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
configClass.addImportedResource(resolvedResource, readerClass);
}
}
// 处理 @Bean methods
// Process individual @Bean methods
Set beanMethods = retrieveBeanMethodMetadata(sourceClass);
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
//处理接口
// Process default methods on interfaces
processInterfaces(configClass, sourceClass);
// 处理超类的
// Process superclass, if any
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;
}
=========================================================
//通过组件扫描器进行真正的解析
>org.springframework.context.annotation.ComponentScanAnnotationParser#parse
public Set parse(AnnotationAttributes componentScan, final String declaringClass) {
//创建一个类路径下的bean定义扫描器
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);
//为扫描器设置一个bean 名称的生成器
Class 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 resolverClass = componentScan.getClass("scopeResolver");
scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
}
scanner.setResourcePattern(componentScan.getString("resourcePattern"));
for (AnnotationAttributes filter : componentScan.getAnnotationArray("includeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addIncludeFilter(typeFilter);
}
}
for (AnnotationAttributes filter : componentScan.getAnnotationArray("excludeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addExcludeFilter(typeFilter);
}
}
boolean lazyInit = componentScan.getBoolean("lazyInit");
if (lazyInit) {
scanner.getBeanDefinitionDefaults().setLazyInit(true);
}
Set 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);
}
});
//真正扫描器扫描指定路径
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
===========================================================
>org.springframework.context.annotation.ClassPathBeanDefinitionScanner#ClassPathBeanDefinitionScanner
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, @Nullable ResourceLoader resourceLoader) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
//使用默认的扫描规则
if (useDefaultFilters) {
registerDefaultFilters();
}
//设置环境变量
setEnvironment(environment);
//设置资源加载器
setResourceLoader(resourceLoader);
}
=====================================
//默认的扫描规则
protected void registerDefaultFilters() {
//添加了Componet的解析，这就是我们为啥@Componet @Respository @Service @Controller的 @AspectJ
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
try {
//添加Jsr 250规范的注解
this.includeFilters.add(new AnnotationTypeFilter(
((Class) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));
logger.debug("JSR-250 'javax.annotation.ManagedBean' found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-250 1.1 API (as included in Java EE 6) not available - simply skip.
}
try {
//JSR330的注解
this.includeFilters.add(new AnnotationTypeFilter(
((Class) ClassUtils.forName("javax.inject.Named", cl)), false));
logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
===================================================
使用扫描器去真正的扫描类,返回Set
>org.springframework.context.annotation.ClassPathBeanDefinitionScanner#doScan
protected Set doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
////创建一个Bean定义 holder的 set
Set beanDefinitions = new LinkedHashSet<>();
//循环扫描路径
for (String basePackage : basePackages) {
//找到候选的组件集合
Set candidates = findCandidateComponents(basePackage);
//循环候选组件集合
for (BeanDefinition candidate : candidates) {
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
//生成bean的名称
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
//判断是不是抽象的bean定义
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
//注解的bean定义
if (candidate instanceof AnnotatedBeanDefinition) {
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
if (checkCandidate(beanName, candidate)) { //检查当前的和存主的bean定义是否有冲突
//把候选的组件封装成BeanDefinitionHolder
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
//加入到bean定义的集合中
beanDefinitions.add(definitionHolder);
//注册当前的bean定义信息
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
=========================================================
>org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#findCandidateComponents
找到候选的组件 返回Set的集合
>org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#scanCandidateComponents
private Set scanCandidateComponents(String basePackage) {
// //候选的bean定义信息
Set candidates = new LinkedHashSet<>();
try {
//拼接需要扫描包下面的类的路径 classpath*:com/niuh/testapplicationlistener/**/*.class
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
//把路径解析成一个个.class文件
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
//循环.class文件的resource对象
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
//判断class文件是否可读
if (resource.isReadable()) {
try {
//把resource对象 变为一个类的原信息读取器
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
//判断类的源信息读取器是否为候选的组件
if (isCandidateComponent(metadataReader)) { //是候选的组件
//把类元信息读取器封装成一个ScannedGenericBeanDefinition
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
//是候选的组件
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
//把当前解析出来的定义的加入到 BeanDefinition的集合中
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;
}
===========================================
是不是需要扫描的组件
org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#isCandidateComponent
protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {
//是不是被排除的
for (TypeFilter tf : this.excludeFilters) {
if (tf.match(metadataReader, this.metadataReaderFactory)) {
return false;
}
}
//在被包含的组件
for (TypeFilter tf : this.includeFilters) {
if (tf.match(metadataReader, this.metadataReaderFactory)) {
return isConditionMatch(metadataReader);
}
}
return false;
}
==============================================================
是否能够进行@Conditional判断
org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#isConditionMatch
private boolean isConditionMatch(MetadataReader metadataReader) {
if (this.conditionEvaluator == null) {
this.conditionEvaluator = new ConditionEvaluator(getRegistry(), getEnvironment(), getResourceLoader());
}
return !this.conditionEvaluator.shouldSkip(metadataReader.getAnnotationMetadata());
}