@ComponentScan源码分析详解
1. 进入AbstractApplicationContext抽象类中，找到refresh()方法，找到方法中invokeBeanFactoryPostProcessors()这一句
public void refresh() throws BeansException, IllegalStateException {
Object var1 = this.startupShutdownMonitor;
synchronized(this.startupShutdownMonitor) {
this.prepareRefresh();
ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
this.prepareBeanFactory(beanFactory);
try {
this.postProcessBeanFactory(beanFactory);
// 调用工厂后置处理器注册bean到context中
this.invokeBeanFactoryPostProcessors(beanFactory);
this.registerBeanPostProcessors(beanFactory);
this.initMessageSource();
this.initApplicationEventMulticaster();
this.onRefresh();
this.registerListeners();
this.finishBeanFactoryInitialization(beanFactory);
this.finishRefresh();2. 进入invokeBeanFactoryPostProcessors()方法中
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, this.getBeanFactoryPostProcessors());
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean("loadTimeWeaver")) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}3. 进入PostProcessorRegistrationDelegate类中invokeBeanFactoryPostProcessors()方法中，找到关键方法invokeBeanDefinitionRegistryPostProcessors()
4. 进入invokeBeanDefinitionRegistryPostProcessors()中，遍历BeanDefinitionRegistryPostProcessor处理BeanDefinitionRegistry
private static void invokeBeanDefinitionRegistryPostProcessors(Collection postProcessors, BeanDefinitionRegistry registry) {
Iterator var2 = postProcessors.iterator();
while(var2.hasNext()) {
BeanDefinitionRegistryPostProcessor postProcessor = (BeanDefinitionRegistryPostProcessor)var2.next();
// 处理BeanDefinitionRegistry
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}5. 进入postProcessBeanDefinitionRegistry()方法中，实现类是ConfigurationClassPostProcessor。找到核心功能processConfigBeanDefinitions()
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException("postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
} else if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException("postProcessBeanFactory already called on this post-processor against " + registry);
} else {
this.registriesPostProcessed.add(registryId);
this.processConfigBeanDefinitions(registry);
}
}上述代码主要作用：
1. 生成registryId,加入到registriesPostProcessed中，registriesPostProcessed是为了做去重判断，当重复对一个BeanDefinitionRegistry进行处理时，会抛出异常
6. 进入processConfigBeanDefinitions()方法中
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List configCandidates = new ArrayList();
// 1.获取已经注册的bean名称
String[] candidateNames = registry.getBeanDefinitionNames();
String[] var4 = candidateNames;
int var5 = candidateNames.length;
for(int var6 = 0; var6 < var5; ++var6) {
String beanName = var4[var6];
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
// 1.1 如果BeanDefinition中的configurationClass不为null或者lite,则意味着
// 1.1 还没有处理过，进行处理
if (!ConfigurationClassUtils.isFullConfigurationClass(beanDef) && !ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
// 1.2 判断bean是否为configurationClass，如果是，则加入到configCandidates中
if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
} else if (this.logger.isDebugEnabled()) {
this.logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
// 2.对configCandidates进行排序，按照@Order配置的值进行排序
if (!configCandidates.isEmpty()) {
configCandidates.sort((bd1, bd2) -> {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return i1 < i2 ? -1 : (i1 > i2 ? 1 : 0);
});
SingletonBeanRegistry sbr = null;
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry)registry;
if (!this.localBeanNameGeneratorSet) {
BeanNameGenerator generator = (BeanNameGenerator)sbr.getSingleton("org.springframework.context.annotation.internalConfigurationBeanNameGenerator");
if (generator != null) {
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
}
if (this.environment == null) {
this.environment = new StandardEnvironment();
}
// 3.实例化ConfigurationClassParser为了解析各个配置类
ConfigurationClassParser parser = new ConfigurationClassParser(this.metadataReaderFactory, this.problemReporter, this.environment, this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set candidates = new LinkedHashSet(configCandidates);
HashSet alreadyParsed = new HashSet(configCandidates.size());
do {
// 4.进行解析
parser.parse(candidates);
parser.validate();
Set configClasses = new LinkedHashSet(parser.getConfigurationClasses());
configClasses.removeAll(alreadyParsed);
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 oldCandidateNames = new HashSet(Arrays.asList(candidateNames));
Set alreadyParsedClasses = new HashSet();
Iterator var12 = alreadyParsed.iterator();
while(var12.hasNext()) {
ConfigurationClass configurationClass = (ConfigurationClass)var12.next();
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
String[] var23 = newCandidateNames;
int var24 = newCandidateNames.length;
for(int var14 = 0; var14 < var24; ++var14) {
String candidateName = var23[var14];
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());
if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
((CachingMetadataReaderFactory)this.metadataReaderFactory).clearCache();
}
}
} 上述代码主要作用：
1. 获取已经注册的bean名称,进行遍历
2. 如果BeanDefinition 中的configurationClass 属性不为full 或者lite ,则说明没处理过，需要进行处理
3. 对configCandidates 进行 排序,按照@Order 配置的值进行排序
4. 实例化ConfigurationClassParser 为了解析各个配置类
5. 解析
7. 进入parser.parse(candidates)解析方法具体实现中
public void parse(Set configCandidates) {
this.deferredImportSelectors = new LinkedList();
Iterator var2 = configCandidates.iterator();
while(var2.hasNext()) {
BeanDefinitionHolder holder = (BeanDefinitionHolder)var2.next();
BeanDefinition bd = holder.getBeanDefinition();
try {
if (bd instanceof AnnotatedBeanDefinition) {
this.parse(((AnnotatedBeanDefinition)bd).getMetadata(), holder.getBeanName());
} else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition)bd).hasBeanClass()) {
this.parse(((AbstractBeanDefinition)bd).getBeanClass(), holder.getBeanName());
} else {
this.parse(bd.getBeanClassName(), holder.getBeanName());
}
} catch (BeanDefinitionStoreException var6) {
throw var6;
} catch (Throwable var7) {
throw new BeanDefinitionStoreException("Failed to parse configuration class [" + bd.getBeanClassName() + "]", var7);
}
}
this.processDeferredImportSelectors();
} 上述代码的主要作用：
1. 遍历configCandidates ,进行处理.根据BeanDefinition 的类型 做不同的处理,一般都会调用ConfigurationClassParser#parse 进行解析
8. 进入parse()方法中
protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
this.processConfigurationClass(new ConfigurationClass(metadata, beanName));
}9. 进入processConfigurationClass()方法中
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
// 1.判断是否应该跳过
if (!this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
ConfigurationClass existingClass = (ConfigurationClass)this.configurationClasses.get(configClass);
if (existingClass != null) {
// 2.处理Imported的情况
if (configClass.isImported()) {
if (existingClass.isImported()) {
existingClass.mergeImportedBy(configClass);
}
return;
}
this.configurationClasses.remove(configClass);
this.knownSuperclasses.values().removeIf(configClass::equals);
}
ConfigurationClassParser.SourceClass sourceClass = this.asSourceClass(configClass);
do {
// 3.递归调用进行解析
sourceClass = this.doProcessConfigurationClass(configClass, sourceClass);
} while(sourceClass != null);
// 4.添加到configurationClass中
this.configurationClasses.put(configClass, configClass);
}
}上述代码的主要作用：
1. 判断是否跳过
2. 处理Imported 的情况
3. 递归调用进行解析
4. 添加到configurationClasses中
10. 进入解析方法中doProcessConfigurationClass
protected final ConfigurationClassParser.SourceClass doProcessConfigurationClass(ConfigurationClass configClass, ConfigurationClassParser.SourceClass sourceClass) throws IOException {
// 1.处理内部类
this.processMemberClasses(configClass, sourceClass);
// 2.处理@PropertySource注解
Iterator var3 = AnnotationConfigUtils.attributesForRepeatable(sourceClass.getMetadata(), PropertySources.class, PropertySource.class).iterator();
AnnotationAttributes importResource;
while(var3.hasNext()) {
importResource = (AnnotationAttributes)var3.next();
if (this.environment instanceof ConfigurableEnvironment) {
this.processPropertySource(importResource);
} else {
this.logger.warn("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() + "]. Reason: Environment must implement ConfigurableEnvironment");
}
}
// 3.处理@ComponentScan注解
Set componentScans = AnnotationConfigUtils.attributesForRepeatable(sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() && !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
Iterator var13 = componentScans.iterator();
while(var13.hasNext()) {
AnnotationAttributes componentScan = (AnnotationAttributes)var13.next();
// 3.1 进行扫描
Set scannedBeanDefinitions = this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
Iterator var7 = scannedBeanDefinitions.iterator();
// 3.2 依次遍历扫描的配置类进行解析
while(var7.hasNext()) {
BeanDefinitionHolder holder = (BeanDefinitionHolder)var7.next();
if (ConfigurationClassUtils.checkConfigurationClassCandidate(holder.getBeanDefinition(), this.metadataReaderFactory)) {
this.parse(holder.getBeanDefinition().getBeanClassName(), holder.getBeanName());
}
}
}
} 上述代码的作用作用：
1. 处理内部类
2. 处理@PropertySource注解
3. 处理@ComponentScan注解
11. 主要看处理@ComponentScan注解，找到this.componentScanParser.parse()方法，进入parse()方法中，看到方法的最后一段中，doScan方法
12. 进入doScan()方法中，找到关键方法findCandidateComponents()方法
13. 进入findCandidateComponents()方法具体实现中，找到scanCandidateComponents()方法
14. 进入scanCandidateComponents()方法的具体实现中，找到this.isCandidateComponent()方法中
15. 进入isCandidateComponent()方法中
上述代码的主要作用：
1. includeFilters默认包括了@Component，因此调用tf.match就通过了