标签：null return String beanFactory invokeBeanFactoryPostProcessor refresh new 解析 cla
【接上文】
5. invokeBeanFactoryPostProcessors(beanFactory);
看名称是在调用BeanFactoryPostProcessor的实现类的方法。
疑问: 什么时候去找的BeanFactoryPostProcessor的实现类的。
AbstractApplicationContext#invokeBeanFactoryPostProcessors
/**
* Instantiate and invoke all registered BeanFactoryPostProcessor beans,
* respecting explicit order if given.
* <p>Must be called before singleton instantiation.
*/
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 (!IN_NATIVE_IMAGE && beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
关键在这句:PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors()); 继续跟进。
PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
// 通过上面的代码可以知道beanFactory的实现类其实是DefaultListableBeanFactory,我们暂且只看下这个类的定义。
// public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory
// implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable
// 可以看到这里的DefaultListableBeanFactory是实现了BeanDefinitionRegistry接口的，这里的if判断结果是true
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
//这里的beanFactoryPostProcessor 会不会包含自定义的beanFactoryPostProcessor呢
//大概猜测下 这里之前的步骤并没有检测beanFactoryPostProcessor的过程，这里如果有的话就是系统内置的beanFactoryPostProcessor
//在AbstractApplicationContext中传参使用的是默认的值 也就是新new出来的一个list 这里的for循环目前是不会走里面的内容的。
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.
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
//CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME --> ConfigurationClassPostProcessor -->实现了BeanDefinitionRegistryPostProcessor，PriorityOrdered
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//所以这里取到的beanName是CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME这个常量对应的值
for (String ppName : postProcessorNames) {
//判断这个bean是否实现了PriorityOrdered接口 显然这里是返回true的
//NOTE:前面的分析中提到过可以用户自定义特殊beanFactory的操作 所以这里的循环和if判断都是有价值的
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
//beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)获取到的就是ConfigurationClassPostProcessor
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//对后置处理器进行排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//加入到已注册的后置处理器集合中
registryProcessors.addAll(currentRegistryProcessors);
//这里真正调用后置处理器的方法，具体分析下。 这里currentRegistryProcessors里面装的就是ConfigurationClassPostProcessor
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
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, beanFactory.getApplicationStartup());
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, beanFactory.getApplicationStartup());
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<>(orderedPostProcessorNames.size());
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<>(nonOrderedPostProcessorNames.size());
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();
}
关注下invokeBeanDefinitionRegistryPostProcessors这个方法，遍历postProcessors执行每个postProcessor的postProcessBeanDefinitionRegistry方法，
这里postProcessor是ConfigurationClassPostProcessor的实例。
/**
* Invoke the given BeanDefinitionRegistryPostProcessor beans.
* 调用指定的BeanDefinitionRegistryPostProcessor
*/
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry, ApplicationStartup applicationStartup) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
StartupStep postProcessBeanDefRegistry = applicationStartup.start("spring.context.beandef-registry.post-process")
.tag("postProcessor", postProcessor::toString);
postProcessor.postProcessBeanDefinitionRegistry(registry);
postProcessBeanDefRegistry.end();
}
}
继续跟进postProcessor.postProcessBeanDefinitionRegistry(registry);其实就是ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry方法。
ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry
/**
* Derive further bean definitions from the configuration classes in the registry.
* 驱动注册在当前注册器中的配置类中更多的beanDefinition
*/
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
}
if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanFactory already called on this post-processor against " + registry);
}
this.registriesPostProcessed.add(registryId);
processConfigBeanDefinitions(registry);
}
/**
* Build and validate a configuration model based on the registry of
* {@link Configuration} classes.
*/
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
//这里得到的candidates是五个开天辟地的bean和启动配置类bean
String[] candidateNames = registry.getBeanDefinitionNames();
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
//判断是否是@Configuration注解的类 这里启动类只注册了beanName和beanType 所以返回是null 走else if的条件判断
if (beanDef.getAttribute(ConfigurationClassUtils.CONFIGURATION_CLASS_ATTRIBUTE) != null) {
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
// 这里的configCandidates只有一个就是启动配置类
if (configCandidates.isEmpty()) {
return;
}
// Sort by previously determined @Order value, if applicable
// 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
//检查是否有bean名称生成器bean存在 显然目前是没有的，暂时跳过
SingletonBeanRegistry sbr = null;
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet) {
BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(
AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR);
if (generator != null) {
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
}
// 环境是有值的
if (this.environment == null) {
this.environment = new StandardEnvironment();
}
// Parse each @Configuration class
// 解析@Configuration 和 @Component标签 这个parser可以先研究下。
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());
//迭代解析相关BeanDefinition信息
do {
StartupStep processConfig = this.applicationStartup.start("spring.context.config-classes.parse");
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);
processConfig.tag("classCount", () -> String.valueOf(configClasses.size())).end();
candidates.clear();
//如果有新检测出来的beanDefinition 做相应处理
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
// 注册ImportRegistry成一个bean
if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
//清空外部MetadataReaderFactory提供的缓存信息
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();
}
}
再简单看下ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)这个方法。
/**
* Check whether the given bean definition is a candidate for a configuration class
* (or a nested component class declared within a configuration/component class,
* to be auto-registered as well), and mark it accordingly.
* 检查给定的beanDefinition是否是一个配置类的候选类或者有内置的@Configuration 、@Component类
* @param beanDef the bean definition to check
* @param metadataReaderFactory the current factory in use by the caller
* @return whether the candidate qualifies as (any kind of) configuration class
*/
public static boolean checkConfigurationClassCandidate(
BeanDefinition beanDef, MetadataReaderFactory metadataReaderFactory) {
String className = beanDef.getBeanClassName();
if (className == null || beanDef.getFactoryMethodName() != null) {
return false;
}
AnnotationMetadata metadata;
if (beanDef instanceof AnnotatedBeanDefinition &&
className.equals(((AnnotatedBeanDefinition) beanDef).getMetadata().getClassName())) {
// Can reuse the pre-parsed metadata from the given BeanDefinition...
//实际appConfig走的是这个分支
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;
}
}
// 获取注解元信息 proxyBeanMethods -> true 后续走到返回true的结果 如果包含@Configuration 设置为Full
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);
}
/**
* candidateIndicators.add(Component.class.getName());
candidateIndicators.add(ComponentScan.class.getName());
candidateIndicators.add(Import.class.getName());
candidateIndicators.add(ImportResource.class.getName());
*/
//如果是包含@Component @ComponentScan @Import @ImportSource 则设置为 Lite
else if (config != null || isConfigurationCandidate(metadata)) {
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE);
}
else {
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;
}
这个方法AppConfig走到了return true;这个结果。到此为止。
下面看下这个ConfigurationClassParser的parse方法
public void parse(Set<BeanDefinitionHolder> configCandidates) {
for (BeanDefinitionHolder holder : configCandidates) {
BeanDefinition bd = holder.getBeanDefinition();
try {
//由于目前走的是注解的流程 这里就走到了bd instanceof AnnotatedBeanDefinition这个条件里
if (bd instanceof AnnotatedBeanDefinition) {
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);
}
}
this.deferredImportSelectorHandler.process();
}
protected final void parse(@Nullable String className, String beanName) throws IOException {
Assert.notNull(className, "No bean class name for configuration class bean definition");
MetadataReader reader = this.metadataReaderFactory.getMetadataReader(className);
processConfigurationClass(new ConfigurationClass(reader, beanName), DEFAULT_EXCLUSION_FILTER);
}
protected final void parse(Class<?> clazz, String beanName) throws IOException {
processConfigurationClass(new ConfigurationClass(clazz, beanName), DEFAULT_EXCLUSION_FILTER);
}
protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
//接着就走到了这个解析方法
processConfigurationClass(new ConfigurationClass(metadata, beanName), DEFAULT_EXCLUSION_FILTER);
}
protected void processConfigurationClass(ConfigurationClass configClass, Predicate<String> filter) 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.
SourceClass sourceClass = asSourceClass(configClass, filter);
do {
//关注下这个方法
sourceClass = doProcessConfigurationClass(configClass, sourceClass, filter);
}
while (sourceClass != null);
this.configurationClasses.put(configClass, configClass);
}
/**
* Apply processing and build a complete {@link ConfigurationClass} by reading the
* annotations, members and methods from the source class. This method can be called
* multiple times as relevant sources are discovered.
* 通过读取启动配置类的注解、成员和方法创建一个完整的ConfigurationClass
* @param configClass the configuration class being build
* @param sourceClass a source class
* @return the superclass, or {@code null} if none found or previously processed
*/
@Nullable
protected final SourceClass doProcessConfigurationClass(
ConfigurationClass configClass, SourceClass sourceClass, Predicate<String> filter)
throws IOException {
//判断是否有@Component注解 有 走if内流程
if (configClass.getMetadata().isAnnotated(Component.class.getName())) {
// Recursively process any member (nested) classes first
// 解析内部成员属性或者类对象
processMemberClasses(configClass, sourceClass, filter);
}
//解析@PropertySource注解
// Process any @PropertySource annotations
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");
}
}
//解析@ComponentScan 和 @ComponentScans 注解
// Process any @ComponentScan annotations
Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() &&
!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
//这里取到的只有一个@ComponentScan(basePackages="com.zjtx.tech.demo") 是个注解对象 可以通过对应方法获取到注解内容
for (AnnotationAttributes componentScan : componentScans) {
// The config class is annotated with @ComponentScan -> perform the scan immediately
// 存在@ComponentScan注解则对注解内容或者包进行解析和加载
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();
}
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
// 解析@Import注解
processImports(configClass, sourceClass, getImports(sourceClass), filter, true);
// 解析@ImportSource注解
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
//解析单独的@Bean
Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
// Process default methods on interfaces
// 解析接口上的默认方法
processInterfaces(configClass, sourceClass);
// 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;
}
//限于篇幅，其他内先省略....
}
可以看到这个ConfigurationClassParser是解析一系列注解的关键类，这些注解包括:
-
@Component --> 解析内部类看是否有相关注解
-
@PropertySource
-
@ComponentScan
-
@Import
-
@ImportSource
-
@Bean
-
处理接口默认实现
-
父类注解解析，如果没有父类了则返回null
解析入口是个do…while循环，上面分析可以知道如果解析的类没有父类就会返回null,解析的过程和顺序就是上面分析的那些。
// Recursively process the configuration class and its superclass hierarchy.
SourceClass sourceClass = asSourceClass(configClass, filter);
do {
//关注下这个方法
sourceClass = doProcessConfigurationClass(configClass, sourceClass, filter);
}
while (sourceClass != null);
下面一个一个看。
-
@Component解析 只摘取关键片段
//判断是否有@Component注解 有 走if内流程 if (configClass.getMetadata().isAnnotated(Component.class.getName())) { // Recursively process any member (nested) classes first // 解析内部成员属性或者类对象 processMemberClasses(configClass, sourceClass, filter); } /** * 解析@Component过程中对内部类进行处理 */ private void processMemberClasses(ConfigurationClass configClass, SourceClass sourceClass, Predicate<String> filter) throws IOException { Collection<SourceClass> memberClasses = sourceClass.getMemberClasses(); if (!memberClasses.isEmpty()) { List<SourceClass> candidates = new ArrayList<>(memberClasses.size()); for (SourceClass memberClass : memberClasses) { //这个方法上面分析过 只要有@Configuration @Component @ComponentScan @Import @ImportSource都会返回true if (ConfigurationClassUtils.isConfigurationCandidate(memberClass.getMetadata()) && !memberClass.getMetadata().getClassName().equals(configClass.getMetadata().getClassName())) { candidates.add(memberClass); } } OrderComparator.sort(candidates); for (SourceClass candidate : candidates) { if (this.importStack.contains(configClass)) { this.problemReporter.error(new CircularImportProblem(configClass, this.importStack)); } else { this.importStack.push(configClass); try { //作为配置类解析 又回到了processConfigurationClass这个方法 进行新一轮迭代 processConfigurationClass(candidate.asConfigClass(configClass), filter); } finally { this.importStack.pop(); } } } } }- @PropertySource 注解解析过程
@Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Repeatable(PropertySources.class) public @interface PropertySource { /** * 指定配置文件的名称，如果省略了会使用ResourcePropertySource的单参构造方法生成名称 */ String name() default ""; /** * 指定资源文件的位置 支持file和classpath开头的配置 * 不支持模糊匹配 * 占位符的匹配会通过资源文件来获取对应的值 * 每个位置都会被按声明顺序加入到environment中作为它自己的资源文件 */ String[] value(); /** * 指定是否需要在找不到对应文件时进行异常抛出 * @since 4.0 */ boolean ignoreResourceNotFound() default false; /** * 指定编码格式 * @since 4.3 */ String encoding() default ""; /** * 指定一个自定义的资源属性工厂，默认会使用DefaultPropertySourceFactory * @since 4.3 */ Class<? extends PropertySourceFactory> factory() default PropertySourceFactory.class; }// Process any @PropertySource annotations 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 the given <code>@PropertySource</code> annotation metadata. * @param propertySource metadata for the <code>@PropertySource</code> annotation found * @throws IOException if loading a property source failed */ private void processPropertySource(AnnotationAttributes propertySource) throws IOException { String name = propertySource.getString("name"); if (!StringUtils.hasLength(name)) { name = null; } String encoding = propertySource.getString("encoding"); if (!StringUtils.hasLength(encoding)) { encoding = null; } String[] locations = propertySource.getStringArray("value"); Assert.isTrue(locations.length > 0, "At least one @PropertySource(value) location is required"); boolean ignoreResourceNotFound = propertySource.getBoolean("ignoreResourceNotFound"); Class<? extends PropertySourceFactory> factoryClass = propertySource.getClass("factory"); PropertySourceFactory factory = (factoryClass == PropertySourceFactory.class ? DEFAULT_PROPERTY_SOURCE_FACTORY : BeanUtils.instantiateClass(factoryClass)); for (String location : locations) { try { String resolvedLocation = this.environment.resolveRequiredPlaceholders(location); Resource resource = this.resourceLoader.getResource(resolvedLocation); addPropertySource(factory.createPropertySource(name, new EncodedResource(resource, encoding))); } catch (IllegalArgumentException | FileNotFoundException | UnknownHostException | SocketException ex) { // Placeholders not resolvable or resource not found when trying to open it if (ignoreResourceNotFound) { if (logger.isInfoEnabled()) { logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage()); } } else { throw ex; } } } }String resolvedLocation = this.environment.resolveRequiredPlaceholders(location); AbstractEnvironment#resolveRequiredPlaceholders
@Override public String resolveRequiredPlaceholders(String text) throws IllegalArgumentException { return this.propertyResolver.resolveRequiredPlaceholders(text); }propertyResolver是个接口，实现类这里用到的是AbstractPropertyResolver
AbstractPropertyResolver#resolveRequiredPlaceholders
@Override public String resolveRequiredPlaceholders(String text) throws IllegalArgumentException { //如果strictHelper为null则新创建一个 if (this.strictHelper == null) { this.strictHelper = createPlaceholderHelper(false); } return doResolvePlaceholders(text, this.strictHelper); } //真正解析占位符的入口方法 private String doResolvePlaceholders(String text, PropertyPlaceholderHelper helper) { return helper.replacePlaceholders(text, this::getPropertyAsRawString); }可以看到真正的占位符解析过程是交给PropertyPlaceholderHelper这个类来处理的。看下这个类的对应方法replacePlaceholders。
PropertyPlaceholderHelper#replacePlaceholders
/**
* Replaces all placeholders of format {@code ${name}} with the value returned
* from the supplied {@link PlaceholderResolver}.
* @param value the value containing the placeholders to be replaced
* @param placeholderResolver the {@code PlaceholderResolver} to use for replacement
* @return the supplied value with placeholders replaced inline
*/
public String replacePlaceholders(String value, PlaceholderResolver placeholderResolver) {
Assert.notNull(value, "'value' must not be null");
return parseStringValue(value, placeholderResolver, null);
}
protected String parseStringValue(
String value, PlaceholderResolver placeholderResolver, @Nullable Set<String> visitedPlaceholders) {
int startIndex = value.indexOf(this.placeholderPrefix);
if (startIndex == -1) {
return value;
}
StringBuilder result = new StringBuilder(value);
while (startIndex != -1) {
int endIndex = findPlaceholderEndIndex(result, startIndex);
if (endIndex != -1) {
String placeholder = result.substring(startIndex + this.placeholderPrefix.length(), endIndex);
String originalPlaceholder = placeholder;
if (visitedPlaceholders == null) {
visitedPlaceholders = new HashSet<>(4);
}
if (!visitedPlaceholders.add(originalPlaceholder)) {
throw new IllegalArgumentException(
"Circular placeholder reference '" + originalPlaceholder + "' in property definitions");
}
// Recursive invocation, parsing placeholders contained in the placeholder key.
//递归调用 可以看出这里是支持叠加占位符的 如 ${${${}}}
placeholder = parseStringValue(placeholder, placeholderResolver, visitedPlaceholders);
// Now obtain the value for the fully resolved key...
String propVal = placeholderResolver.resolvePlaceholder(placeholder);
if (propVal == null && this.valueSeparator != null) {
int separatorIndex = placeholder.indexOf(this.valueSeparator);
if (separatorIndex != -1) {
String actualPlaceholder = placeholder.substring(0, separatorIndex);
String defaultValue = placeholder.substring(separatorIndex + this.valueSeparator.length());
propVal = placeholderResolver.resolvePlaceholder(actualPlaceholder);
if (propVal == null) {
propVal = defaultValue;
}
}
}
if (propVal != null) {
// Recursive invocation, parsing placeholders contained in the
// previously resolved placeholder value.
propVal = parseStringValue(propVal, placeholderResolver, visitedPlaceholders);
result.replace(startIndex, endIndex + this.placeholderSuffix.length(), propVal);
if (logger.isTraceEnabled()) {
logger.trace("Resolved placeholder '" + placeholder + "'");
}
startIndex = result.indexOf(this.placeholderPrefix, startIndex + propVal.length());
}
else if (this.ignoreUnresolvablePlaceholders) {
// Proceed with unprocessed value.
startIndex = result.indexOf(this.placeholderPrefix, endIndex + this.placeholderSuffix.length());
}
else {
throw new IllegalArgumentException("Could not resolve placeholder '" +
placeholder + "'" + " in value \"" + value + "\"");
}
visitedPlaceholders.remove(originalPlaceholder);
}
else {
startIndex = -1;
}
}
return result.toString();
}
这两个方法实际就是对字符串占位符（${}）的一些列操作和替换。
- @ComponentScan注解解析
// Process any @ComponentScan annotations
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
// 注解了@ComponentScan的配置类,直接根据配置进行检索
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();
}
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
@ComponentScans是@ComponentScan的集合，定义注解的时候添加了@Repeatable,这里通过attributesForRepeatable把这两种都解析了。
/**
* 解析@ComponentScans 和 @ComponentScan 转换成AnnotationAttributes集合
*/
@SuppressWarnings("unchecked")
static Set<AnnotationAttributes> attributesForRepeatable(
AnnotationMetadata metadata, String containerClassName, String annotationClassName) {
Set<AnnotationAttributes> result = new LinkedHashSet<>();
// Direct annotation present?
addAttributesIfNotNull(result, metadata.getAnnotationAttributes(annotationClassName, false));
// Container annotation present?
Map<String, Object> container = metadata.getAnnotationAttributes(containerClassName, false);
if (container != null && container.containsKey("value")) {
for (Map<String, Object> containedAttributes : (Map<String, Object>[]) container.get("value")) {
addAttributesIfNotNull(result, containedAttributes);
}
}
// Return merged result
return Collections.unmodifiableSet(result);
}
//把注解解析出来的数据转换成AnnotationAttributes 存放到result中
private static void addAttributesIfNotNull(
Set<AnnotationAttributes> result, @Nullable Map<String, Object> attributes) {
if (attributes != null) {
result.add(AnnotationAttributes.fromMap(attributes));
}
}
接下来就是根据里面的value进行包里的组件搜索,先看下ConfigurationClassParser的构造方法。
/**
* Create a new {@link ConfigurationClassParser} instance that will be used
* to populate the set of configuration classes.
*/
public ConfigurationClassParser(MetadataReaderFactory metadataReaderFactory,
ProblemReporter problemReporter, Environment environment, ResourceLoader resourceLoader,
BeanNameGenerator componentScanBeanNameGenerator, BeanDefinitionRegistry registry) {
this.metadataReaderFactory = metadataReaderFactory;
this.problemReporter = problemReporter;
this.environment = environment;
this.resourceLoader = resourceLoader;
this.registry = registry;
this.componentScanParser = new ComponentScanAnnotationParser(
environment, resourceLoader, componentScanBeanNameGenerator, registry);
this.conditionEvaluator = new ConditionEvaluator(registry, environment, resourceLoader);
}
再看下ComponentScanAnnotationParser的parse方法。
ComponentScanAnnotationParser#parse
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);
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"));
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<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);
}
});
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
可以看到前面都是在解析注解中的属性配置，最终是调用了ClassPathBeanDefinitionScanner#doScan方法。
ClassPathBeanDefinitionScanner#doScan
/**
* Perform a scan within the specified base packages, returning the registered bean definitions.
* <p>This method does <i>not</i> register an annotation config processor
* but rather leaves this up to the caller.
* @param basePackages the packages to check for annotated classes
* @return set of beans registered if any for tooling registration purposes (never {@code null})
*/
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
for (String basePackage : basePackages) {
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
for (BeanDefinition candidate : candidates) {
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
if (candidate instanceof AnnotatedBeanDefinition) {
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
if (checkCandidate(beanName, candidate)) {
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
beanDefinitions.add(definitionHolder);
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
/**
* Scan the class path for candidate components.
* @param basePackage the package to check for annotated classes
* @return a corresponding Set of autodetected bean definitions
*/
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
else {
return scanCandidateComponents(basePackage);
}
}
/**
* Determine if the index can be used by this instance.
* @return {@code true} if the index is available and the configuration of this
* instance is supported by it, {@code false} otherwise
* @since 5.0
*/
private boolean indexSupportsIncludeFilters() {
for (TypeFilter includeFilter : this.includeFilters) {
if (!indexSupportsIncludeFilter(includeFilter)) {
return false;
}
}
return true;
}
/**
* Determine if the specified include {@link TypeFilter} is supported by the index.
* @param filter the filter to check
* @return whether the index supports this include filter
* @since 5.0
* @see #extractStereotype(TypeFilter)
*/
private boolean indexSupportsIncludeFilter(TypeFilter filter) {
if (filter instanceof AnnotationTypeFilter) {
Class<? extends Annotation> annotation = ((AnnotationTypeFilter) filter).getAnnotationType();
return (AnnotationUtils.isAnnotationDeclaredLocally(Indexed.class, annotation) ||
annotation.getName().startsWith("javax."));
}
if (filter instanceof AssignableTypeFilter) {
Class<?> target = ((AssignableTypeFilter) filter).getTargetType();
return AnnotationUtils.isAnnotationDeclaredLocally(Indexed.class, target);
}
return false;
}
private Set<BeanDefinition> addCandidateComponentsFromIndex(CandidateComponentsIndex index, String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
Set<String> types = new HashSet<>();
for (TypeFilter filter : this.includeFilters) {
String stereotype = extractStereotype(filter);
if (stereotype == null) {
throw new IllegalArgumentException("Failed to extract stereotype from " + filter);
}
types.addAll(index.getCandidateTypes(basePackage, stereotype));
}
for (String type : types) {
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(type);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(metadataReader.getResource());
if (isCandidateComponent(sbd)) {
candidates.add(sbd);
}
}
}
} catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
/**
* 这里会把@Component注解的类找出来 包含内置@Component注解的类 如@Controller @Service @Repository
*/
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
// 1.根据指定包名 生成包搜索路径
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
//2. 资源加载器 加载搜索路径下的 所有class 转换为 Resource[]
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
// 3. 循环 处理每一个 resource
for (Resource resource : resources) {
if (resource.isReadable()) {
try {
// 读取类的 注解信息 和 类信息 ，信息储存到 MetadataReader
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
// 执行判断是否符合 过滤器规则，函数内部用过滤器 对metadataReader 过滤
if (isCandidateComponent(metadataReader)) {
//把符合条件的 类转换成 BeanDefinition
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(resource);
// 再次判断 如果是实体类 返回true,如果是抽象类，但是抽象方法 被 @Lookup 注解注释返回true
if (isCandidateComponent(sbd)) {
candidates.add(sbd);
}
}
}catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
}
} catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
/**
* Determine whether the given class does not match any exclude filter
* and does match at least one include filter.
* 判定指定的类是否匹配excludeFilter和includeFilters
* @param metadataReader the ASM ClassReader for the class
* @return whether the class qualifies as a candidate component
*/
protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {
for (TypeFilter tf : this.excludeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
return false;
}
}
for (TypeFilter tf : this.includeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
return isConditionMatch(metadataReader);
}
}
return false;
}
先走excludeFilters如果存在不满足的就直接返回false不往下走了，经过所有的excludeFilters的筛选没有被淘汰，还要再经过includeFilters的筛选，
要是被includeFilters选中，最后还要通过Condition的条件，满足上面所有条件才能算真正的候选bean
（这么一看，成为一个候选bean也不容易）。大致总结一下，没有被excludeFilters淘汰且要同时满足includeFilters和Condition条件。
TypeFilter是个接口，这里用到的实现类是AnnotationTypeFilter。
AnnotationTypeFilter#match
@Override
public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory)
throws IOException {
// This method optimizes avoiding unnecessary creation of ClassReaders
// as well as visiting over those readers.
if (matchSelf(metadataReader)) {
return true;
}
ClassMetadata metadata = metadataReader.getClassMetadata();
if (matchClassName(metadata.getClassName())) {
return true;
}
if (this.considerInherited) {
String superClassName = metadata.getSuperClassName();
if (superClassName != null) {
// Optimization to avoid creating ClassReader for super class.
Boolean superClassMatch = matchSuperClass(superClassName);
if (superClassMatch != null) {
if (superClassMatch.booleanValue()) {
return true;
}
}
else {
// Need to read super class to determine a match...
try {
if (match(metadata.getSuperClassName(), metadataReaderFactory)) {
return true;
}
}
catch (IOException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Could not read super class [" + metadata.getSuperClassName() +
"] of type-filtered class [" + metadata.getClassName() + "]");
}
}
}
}
}
if (this.considerInterfaces) {
for (String ifc : metadata.getInterfaceNames()) {
// Optimization to avoid creating ClassReader for super class
Boolean interfaceMatch = matchInterface(ifc);
if (interfaceMatch != null) {
if (interfaceMatch.booleanValue()) {
return true;
}
}
else {
// Need to read interface to determine a match...
try {
if (match(ifc, metadataReaderFactory)) {
return true;
}
}
catch (IOException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Could not read interface [" + ifc + "] for type-filtered class [" +
metadata.getClassName() + "]");
}
}
}
}
}
return false;
}
这里就是判断给定的类定义信息中是否包含@Component注解，对所有的class进行过滤。
接下来就是转换类信息为BeanDefinition集合
....
//把符合条件的 类转换成 BeanDefinition
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(resource);
// 再次判断 如果是实体类 返回true,如果是抽象类，但是抽象方法 被 @Lookup 注解注释返回true
if (isCandidateComponent(sbd)) {
candidates.add(sbd);
}
return candidates;
....
这里又有个isCandidateComponent(sbd)，我们再看下这个方法。
ClassPathScanningCandidateComponentProvider#isCandidateComponent
/**
* Determine whether the given bean definition qualifies as candidate.
* <p>The default implementation checks whether the class is not an interface
* and not dependent on an enclosing class.
* <p>Can be overridden in subclasses.
* @param beanDefinition the bean definition to check
* @return whether the bean definition qualifies as a candidate component
*/
protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) {
AnnotationMetadata metadata = beanDefinition.getMetadata();
return (metadata.isIndependent() && (metadata.isConcrete() ||
(metadata.isAbstract() && metadata.hasAnnotatedMethods(Lookup.class.getName()))));
}
可以看出要么满足或运算的左边，要么满足或运算的右边。
左边：顶级类或者静态内部类且都是具体的实现类（非抽象类或接口），
右边：是抽象类且必须有@Lookup注释的方法。
通过上面的分析我们已经知道Scanner是如何经过各种筛选，最终筛选出我们想要的候选bean的。
到此ComponentScanAnnotationParser#parse-@ComponentScan就解析完了。
【小结】
解析@ComponentScan和@ComponentScans的属性配置，解析对应包里的class文件，经过bean的条件过滤将符合条件的
class转换成BeanDefinition
标签：null,return,String,beanFactory,invokeBeanFactoryPostProcessor,refresh,new,解析,cla 来源： https://blog.csdn.net/u010361276/article/details/120502481
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