Spring BeanDefinition收集过程示例详解
作者:毛方云
以注解方式说明BeanDefinition的收集过程
调试代码
以注解方式说明BeanDefinition的收集过程,调试代码如下:
public class AnnotationACTest { public static void main(String[] args) { // new一个应用上下文的时候,会注册一些内部的BeanFactoryPostProcessor的beanDefinition AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(); ac.register(BeanConfig.class); ac.refresh(); } }
BeanConfig
@Configuration @ComponentScan("com.mfy.test.bean") @EnableAspectJAutoProxy public class BeanConfig { @Bean public User getUser(){ this.getWoman(); return new User(); } @Bean("women") public Woman getWoman(){ System.out.println("测试@Configuration的类方法内部调用"); return new Woman(); } }
扫描包下的某一个Bean
@Component public class PropertyBean { private String username; private String password; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
创建ApplicationContext对象
创建出来的AnnotationConfigApplicationContext内部会持有DefaultListableBeanFactory(实现了BeanFactory接口的所有方法)
public AnnotationConfigApplicationContext() { // 隐式的会调用父类的构造方法,this.beanFactory = new DefaultListableBeanFactory(); // 此处会添加内部的一些beanDefinition,存储到BeanFactory的beanDefinitionMap this.reader = new AnnotatedBeanDefinitionReader(this); this.scanner = new ClassPathBeanDefinitionScanner(this); }
值得注意的是,创建AnnotatedBeanDefinitionReader的过程,会将ConfigurationClassPostProcessor,AutowiredAnnotationBeanPostProcessor和CommonAnnotationBeanPostProcessor的beanDefinition加入到spring容器中;创建ClassPathBeanDefinitionScanner时,会将@Component注解加入到includeFilters.
注入PostProcessor的代码:
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors( BeanDefinitionRegistry registry, @Nullable Object source) { DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry); if (beanFactory != null) { if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) { beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE); } if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) { beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver()); } } Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8); // 判断BeanFactory中不存在此BeanDefinition,添加ConfigurationClassPostProcessor // ConfigurationClassPostProcessor类负责解析处理所有@Configuration类,并将BeanDefinition注册到BeanFactory中。 if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)); } // AutowiredAnnotationBeanPostProcessor类负责处理@Autowired if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)); } // CommonAnnotationBeanPostProcessor类负责处理@Resource,@PostConstruct,@PreDestroy if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)); } // 省略了部分代码 return beanDefs; }
注入@Component注解
protected void registerDefaultFilters() { // 此处将Component注入,用于后面的识别 this.includeFilters.add(new AnnotationTypeFilter(Component.class)); ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader(); // 省略部分代码 }
通过上面的步骤,只是完成了AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext()
这一行代码的运行.
接下来,要将配置类BeanConfig,手动注入到创建出来的AnnotationConfigApplicationContext中,实际上,是委托给了AnnotatedBeanDefinitionReader来进行配置类的解析工作
public void register(Class<?>... componentClasses) { Assert.notEmpty(componentClasses, "At least one component class must be specified"); // 解析给定的class对象,并存储到beanDefinitionMap this.reader.register(componentClasses); }
this.reader.register(componentClasses)
这行代码,会一直调用到doRegisterBean()
,才会开始真正的逻辑处理,其实只做了一件事,就是生成BeanConfig的BeanDefinition,并注入到spring容器中.
private <T> void doRegisterBean(Class<T> beanClass, @Nullable String name, @Nullable Class<? extends Annotation>[] qualifiers, @Nullable Supplier<T> supplier, @Nullable BeanDefinitionCustomizer[] customizers) { AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(beanClass); if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) { return; } abd.setInstanceSupplier(supplier); ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd); // 设置单例还是原型 abd.setScope(scopeMetadata.getScopeName()); // 设置beanName,当传入的name为null,按照规则,自动生成名称 String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry)); // 解析部分公共的注解(@Lazy,@Primary,@DependsOn,@Role,@Description),并将解析出来的信息填充到beanDefinition中 AnnotationConfigUtils.processCommonDefinitionAnnotations(abd); if (qualifiers != null) { for (Class<? extends Annotation> qualifier : qualifiers) { if (Primary.class == qualifier) { abd.setPrimary(true); } else if (Lazy.class == qualifier) { abd.setLazyInit(true); } else { abd.addQualifier(new AutowireCandidateQualifier(qualifier)); } } } if (customizers != null) { for (BeanDefinitionCustomizer customizer : customizers) { customizer.customize(abd); } } BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName); definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry); // 将解析完成的beanDefinition放入beanFactory中 BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry); }
此时代码运行完了ac.register(BeanConfig.class)
,接下来要刷新容器,即运行ac.refresh()
,这个方法是所有bean进行实例化和初始化的核心,需要重点分析,核心步骤如下:
获取beanFactory
遍历BeanDefinitionRegistryPostProcessor接口的实现类,调用postProcessBeanDefinitionRegistry()方法,将BeanConfig中@ComponentScan覆盖的bean的beanDefinition信息注册到spring容器中
实例化,初始化所有非懒加载的单例bean
public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // Prepare this context for refreshing. prepareRefresh(); // 获取BeanFactory,其实是DefaultListableBeanFactory ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // 设置BeanFactory的类加载器,添加几个BeanPostProcessor,手动注册几个特殊的bean prepareBeanFactory(beanFactory); try { // 扩展点,可以对beanFactory做修改 postProcessBeanFactory(beanFactory); // 实例化BeanFactoryPostProcessor(new应用上下文的时候注册的beanDefinition)并调用,作用是修改beanDefinition的信息 // 例如internalConfigurationAnnotationProcessor,用来解析@Configuration注解类管辖的beanDefinition信息 invokeBeanFactoryPostProcessors(beanFactory); // 实例化各种BeanPostProcessors,并注册到beanFactory的beanPostProcessors属性中 registerBeanPostProcessors(beanFactory); // Initialize message source for this context. initMessageSource(); // 初始化事件广播器(给applicationEventMulticaster赋值) initApplicationEventMulticaster(); // Initialize other special beans in specific context subclasses. onRefresh(); // 注册监听器(非@EventListener注解方式,注册的是实现了ApplicationListener接口的类) registerListeners(); // Instantiate all remaining (non-lazy-init) singletons. finishBeanFactoryInitialization(beanFactory); // Last step: publish corresponding event. finishRefresh(); } // 省略部分代码 }
分析步骤
- 收集实现了PriorityOrdered接口和BeanDefinitionRegistryPostProcessor接口的实现类并调用postProcessBeanDefinitionRegistry(),其实就是调用ConfigurationClassPostProcessor,这个类是spring中的核心类,作用是收集@Component注解的Bean信息,解析成BeanDefinition注册到spring容器中
- 收集实现了Ordered接口和BeanDefinitionRegistryPostProcessor接口的实现类并调用postProcessBeanDefinitionRegistry()
- 死循环收集BeanDefinitionRegistryPostProcessor接口的实现类(排除了前面的)并调用postProcessBeanDefinitionRegistry()
- 调用前面所有BeanDefinitionRegistryPostProcessor接口的实现类的postProcessBeanFactory()方法
- 收集BeanFactoryPostProcessor接口的实现类,也是分成实现了PriorityOrdered接口,Ordered接口和其他的三种情况,然后调用postProcessBeanFactory()方法
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { // 已经完成调用的后置处理器集合 Set<String> processedBeans = new HashSet<>(); // 省略部分代码 List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>(); // 获取实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessor实现类,排序之后,按顺序调用 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); // 目前是调用ConfigurationClassPostProcessor,解析“配置类”的包含的bean信息,变成beanDefinition存入map中 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // 获取实现了Ordered接口的BeanDefinitionRegistryPostProcessor实现类,排序之后,按顺序调用 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // 死循环获取其他所有的BeanDefinitionRegistryPostProcessor实现类,排序之后,按顺序调用 // 死循环BeanDefinitionRegistryPostProcessor实现类的原因是,前面的BeanDefinitionRegistryPostProcessor可能会注入新的实现类, // 所以必须重新再获取并调用一遍 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); // 遍历BeanDefinitionRegistryPostProcessor的实现类,调用postProcessBeanDefinitionRegistry() invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); } // 遍历BeanDefinitionRegistryPostProcessor实现类,调用postProcessBeanFactory() // 对于ConfigurationClassPostProcessor,生成“配置”类(@Configuration)的代理类 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); // 遍历非BeanDefinitionRegistryPostProcessor实现类(自己加进来的),调用postProcessBeanFactory(),基本不会执行 invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // 遍历非BeanDefinitionRegistryPostProcessor实现类(自己加进来的),调用postProcessBeanFactory(),基本不会执行 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) { // 跳过前面已经处理过的BeanFactoryPostProcessor实现类 if (processedBeans.contains(ppName)) { // skip - already processed in first phase above } else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { // 通过beanFactory的getBean(),实例化BeanFactoryPostProcessor 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); beanFactory.clearMetadataCache(); }
下面重点分析一下ConfigurationClassPostProcessor,其实就是分析processConfigBeanDefinitions(),看看是如何将bean变成beanDefinition注册到spring容器
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); // 解析@Component,@ComponentScan,@Import,@ImportResource注解 processConfigBeanDefinitions(registry); }
processConfigBeanDefinitions()实现逻辑
接下来,看看processConfigBeanDefinitions()的实现逻辑,主要流程如下:
- 获取容器中所有已经注册进来的beanName,其实此时只有一个手动注册进来的BeanConfig,其他的全部都是spring自己注册的
- 筛选出@Configuration注解的类,其实就是BeanConfig
- 创建ConfigurationClassParser,是个解析器,作用是解析@ComponentScan注解
- 进行parse(),将@ComponentScan指定的包下所有@Component注解的bean变成beanDefinitiion注册到spring容器中,同时对每一个@Component注解的bean,包装成ConfigurationClass(封装了注解信息metadata,beanName,beanMethods和importedResources),注册到ConfigurationClassParser中的configurationClasses属性
- 遍历configurationClasses中的ConfigurationClass,处理@Bean,@Import和@ImportResource注解,其中,@Bean和@Import会生成beanDefinition注册到spring容器中
- 找出步骤4中注册进来的beanDefinition,判断这些beanDefinition是否存在@Configuration,@ComponentScan,@Component,@ImportResource和@Import注解(至于为什么没有在步骤3中扫描到这些beanDefinition,原因是这些bean不在@ComponentScan所指定的包下),若判断为true,则将重复步骤3~6
经过以上步骤之后,@ComponentScan指定包下的bean都已经变成beanDefinition注册到spring容器中了
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) { List<BeanDefinitionHolder> configCandidates = new ArrayList<>(); String[] candidateNames = registry.getBeanDefinitionNames(); // 筛选具有@Component,@ComponentScan,@Import,@ImportResource注解信息的BeanDefinition for (String beanName : candidateNames) { BeanDefinition beanDef = registry.getBeanDefinition(beanName); if (beanDef.getAttribute(ConfigurationClassUtils.CONFIGURATION_CLASS_ATTRIBUTE) != null) { if (logger.isDebugEnabled()) { logger.debug("Bean definition has already been processed as a configuration class: " + beanDef); } } else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) { // 若是无xml方式配置的,此处只会筛选出@Configuration注解的类(即ac.register(BeanConfig.class)) configCandidates.add(new BeanDefinitionHolder(beanDef, beanName)); } } // Return immediately if no @Configuration classes were found if (configCandidates.isEmpty()) { return; } // Sort by previously determined @Order value, if applicable configCandidates.sort((bd1, bd2) -> { int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition()); int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition()); return Integer.compare(i1, i2); }); // Detect any custom bean name generation strategy supplied through the enclosing application context SingletonBeanRegistry sbr = null; if (registry instanceof SingletonBeanRegistry) { sbr = (SingletonBeanRegistry) registry; if (!this.localBeanNameGeneratorSet) { BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton( AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR); if (generator != null) { this.componentScanBeanNameGenerator = generator; this.importBeanNameGenerator = generator; } } } if (this.environment == null) { this.environment = new StandardEnvironment(); } // 实例化ConfigurationClassParser时,会new一个ComponentScanAnnotationParser对象, // 用来解析@ComponentScan注解对应的bean信息 ConfigurationClassParser parser = new ConfigurationClassParser( this.metadataReaderFactory, this.problemReporter, this.environment, this.resourceLoader, this.componentScanBeanNameGenerator, registry); Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates); Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size()); do { // 解析配置类,变成beanDefinition加入beanFactory的beanDefinitionMap中 // 最终的解析过程是委托给了一个实例化的ClassPathBeanDefinitionScanner类 // 解析出来的配置类,存储在parser的configurationClasses属性中 parser.parse(candidates); parser.validate(); // 得到所有配置类的bean信息 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()); } // 通过ConfigurationClass加载更多的BeanDefinition,通过前面parser.parse(candidates),解析了@bean注解并保存在ConfigurationClass的beanMethods // 再通过beanMethods,生成BeanDefinition信息并注册到beanDefinitionMap中 // 将@ImportResource注解的资源引入spring // 将@Import注解的类,生成BeanDefinition信息并注册到beanDefinitionMap中 this.reader.loadBeanDefinitions(configClasses); alreadyParsed.addAll(configClasses); candidates.clear(); // 如果进入到下面的代码中,则表示原工程中有@Configuration注解的配置类 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())) { // 类似递归,若@Configuration注解的配置类管辖了另外的@Configuration(不在oldCandidateNames集合中),再次循环 candidates.add(new BeanDefinitionHolder(bd, candidateName)); } } } candidateNames = newCandidateNames; } } while (!candidates.isEmpty()); // Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) { sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry()); } if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) { // Clear cache in externally provided MetadataReaderFactory; this is a no-op // for a shared cache since it'll be cleared by the ApplicationContext. ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache(); } }
下面重点分析一下步骤4,解析@ComponentScan的过程,实际上调用的是processConfigurationClass()方法,主要是循环的调用doProcessConfigurationClass(),并且每次跳出循环,都会将configClass注册到属性configurationClasses中
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); } } // 递归的处理配置类configClass及其所继承的父类 // 从当前配置类configClass开始向上沿着类继承结构逐层执行doProcessConfigurationClass(), // 直到遇到的父类是由Java提供的类结束循环 SourceClass sourceClass = asSourceClass(configClass, filter); do { sourceClass = doProcessConfigurationClass(configClass, sourceClass, filter); } while (sourceClass != null); // 需要被处理的配置类configClass已经被分析处理,将它记录到已处理配置类记录 this.configurationClasses.put(configClass, configClass); }
真正处理@ComponentScan的代码逻辑,步骤如下:
- 收集所有被@Component注解并且在@ComponentScan指定的包下的bean,转换成beanDefinition注册到spring容器中
- 遍历步骤1中的beanDefinition,找出存在@Configuration,@ComponentScan,@Component,@ImportResource和@Import注解信息的beanDefinition,调用parse()方法,实际上,再次调用主要是为了解析@Bean,@ComponentScan,@ImportResource和@Import注解,目的也是为了注册这些注解代表的beanDefinition
- 处理@Import注解
- 处理@ImportResource注解
- 处理@Bean注解
TODO 解析的流程
protected final SourceClass doProcessConfigurationClass( ConfigurationClass configClass, SourceClass sourceClass, Predicate<String> filter) throws IOException { if (configClass.getMetadata().isAnnotated(Component.class.getName())) { // 递归处理内部类(内部类也有@Component注解,需要注册到容器中) processMemberClasses(configClass, sourceClass, filter); } // 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.info("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() + "]. Reason: Environment must implement ConfigurableEnvironment"); } } // 处理@ComponentScan注解 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) { // 此configClass存在@ComponentScan注解,扫描获取basePackages的所有bean信息 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(); } // 判断通过@ComponentScan扫描新加入的bdCand,是否存在@Configuration,@ComponentScan,@Component,@ImportResource,@Import注解, // 若有,则再次进入配置类的解析处理流程 if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) { parse(bdCand.getBeanClassName(), holder.getBeanName()); } } } } // 处理@Import注解,给configClass加入ImportBeanDefinitionRegistrar,后续会调用 // getImports(),遍历并递归获取sourceClass的所有注解中包含@import注解的value值 processImports(configClass, sourceClass, getImports(sourceClass), filter, true); // 处理@ImportResource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); } } // 处理@Bean注解,获取注解的方法的相关元数据,比如方法名、所在类全名、返回类型、是否静态、是否不可覆盖等等信息 Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass); for (MethodMetadata methodMetadata : beanMethods) { configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass)); } // Process default methods on interfaces 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; }
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