spring 源码解析一（bean定义）
spring容器的创建
public class MainClass { public static void main(String[] args) { AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class); } }
new AnnotationConfigApplicationContext ()做了哪些事
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) { //调用无参构造器，会调用父类的无参构造器 this(); //注册配置类 register(annotatedClasses); //容器刷新 refresh(); }
1首先调用父类的构造器，创建了ioc容器
public GenericApplicationContext() {
//创建了spring容器，DefaultListableBeanFactory是真正可以作为一个可以独立使用的ioc容器
this.beanFactory = new DefaultListableBeanFactory();
}
2然后调用本身类的无参构造器
public AnnotationConfigApplicationContext() { //为IOC容器赋值 AnnotatedBeanDefinitionReader（注解的Bean定义读取器） this.reader = new AnnotatedBeanDefinitionReader(this); //为IOC容器赋值 类路径下的bean定义扫描器 this.scanner = new ClassPathBeanDefinitionScanner(this); }
2.1 new AnnotatedBeanDefinitionReader（this）
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
//getOrCreateEnvironment创建环境
this(registry, getOrCreateEnvironment(registry)); }
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) { Assert.notNull(registry, "BeanDefinitionRegistry must not be null"); Assert.notNull(environment, "Environment must not be null"); this.registry = registry;
//创建了一个条件计算器 this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
//为容器中注册系统的bean定义信息 AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry); }
2.1.1注册bean定义信息的一些处理器
public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) { registerAnnotationConfigProcessors(registry, null); } public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors( BeanDefinitionRegistry registry, Object source) { //获取ioc容器 DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry); if (beanFactory != null) { //设置默认的排序器 if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) { beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE); } //ContextAnnotationAutoireCandidateResovler用于确定特定的Bean定义是否符合特定的依赖项的候选者 //具体分析可见 https://blog.csdn.net/f641385712/article/details/93620967 if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) { beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver()); } } Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<BeanDefinitionHolder>(8); if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) { //注册一个配置类解析器的bean定义（ConfigurationClassPostProcessor） //该类实现了BeanDefinitionRegistryPostProcessor, //在refresh方法中的invokeBeanFactoryPostProcessors的方法中会被调用 RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)); } if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) { //设置AutoWired注解解析器的bean定义信息 (AutowiredAnnotationBeanPostProcessor) //该类实现了InstantiationAwareBeanPostProcessor， //在实例化前后会被调用，自动注入autoire注解的类 RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)); } if (!registry.containsBeanDefinition(REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) { // 注册解析@Required 注解的处理器 RootBeanDefinition def = new RootBeanDefinition(RequiredAnnotationBeanPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME)); } // Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor. if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) { //检查是否支持JSR250规范，如何支持注册 解析JSR250规范的注解 RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)); } // Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor. if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(); //检查是否支持jpa，若支持注册解析jpa规范的注解 try { def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, AnnotationConfigUtils.class.getClassLoader())); } catch (ClassNotFoundException ex) { throw new IllegalStateException( "Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex); } def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)); } if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) { //注册解析@EventListener的注解 RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME)); } if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME)); } return beanDefs; }
2.2 new ClassPathBeanDefinitionScanner(this)
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry) { this(registry, true); } public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters) { this(registry, useDefaultFilters, getOrCreateEnvironment(registry)); } public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters, Environment environment) { this(registry, useDefaultFilters, environment, (registry instanceof ResourceLoader ? (ResourceLoader) registry : null)); } public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters, Environment environment, ResourceLoader resourceLoader) { Assert.notNull(registry, "BeanDefinitionRegistry must not be null"); this.registry = registry; //使用默认的代码扫描规则 if (useDefaultFilters) { registerDefaultFilters(); } //设置环境 setEnvironment(environment); //设置资源加载器 setResourceLoader(resourceLoader); }
这里虽然新建了一个扫描器，但是实际运用的时候还是重新new了一个，不过程序员在写代码的时候可以从容器中获取这个扫描器。
3注册配置类到容器中 register(annotatedClasses);
public void register(Class<?>... annotatedClasses) { Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified"); this.reader.register(annotatedClasses); } public void register(Class<?>... annotatedClasses) { for (Class<?> annotatedClass : annotatedClasses) { registerBean(annotatedClass); } } public void registerBean(Class<?> annotatedClass) { registerBean(annotatedClass, null, (Class<? extends Annotation>[]) null); } public void registerBean(Class<?> annotatedClass, String name, Class<? extends Annotation>... qualifiers) { AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass); if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) { return; } ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd); abd.setScope(scopeMetadata.getScopeName()); String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry)); 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)); } } } //注册自己传入的主配置类bean定义到容器中 BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName); definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry); BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry); }
4 refresh()方法
public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // Prepare this context for refreshing. prepareRefresh(); // Tell the subclass to refresh the internal bean factory. ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // Prepare the bean factory for use in this context. prepareBeanFactory(beanFactory); try { // Allows post-processing of the bean factory in context subclasses. postProcessBeanFactory(beanFactory); // Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory); // Register bean processors that intercept bean creation. registerBeanPostProcessors(beanFactory); // Initialize message source for this context. initMessageSource(); // Initialize event multicaster for this context. initApplicationEventMulticaster(); // Initialize other special beans in specific context subclasses. onRefresh(); // Check for listener beans and register them. registerListeners(); // Instantiate all remaining (non-lazy-init) singletons. finishBeanFactoryInitialization(beanFactory); // Last step: publish corresponding event. finishRefresh(); } catch (BeansException ex) { if (logger.isWarnEnabled()) { logger.warn("Exception encountered during context initialization - " + "cancelling refresh attempt: " + ex); } // Destroy already created singletons to avoid dangling resources. destroyBeans(); // Reset 'active' flag. cancelRefresh(ex); // Propagate exception to caller. throw ex; } finally { // Reset common introspection caches in Spring's core, since we // might not ever need metadata for singleton beans anymore... resetCommonCaches(); } } }
refresh方法中包含12步，内容众多，先只分析和bean定义相关的，后续再分析其他内容
4.1 invokeBeanFactoryPostProcessors(beanFactory)
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 (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } }
4.2 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors()
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { //这时候传进来的beanFactoryPostProcessors为null // Invoke BeanDefinitionRegistryPostProcessors first, if any. Set<String> processedBeans = new HashSet<String>(); //DefaultListableBeanFactory继承了BeanDefinitionRegistry,所以会走进此分支 if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; //创建一个普通的BeanfactoryPostProcessors的list的组件 List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>(); //创建一个BeanDefinitionRegistryPostProcessor类型的list //BeanDefinitionRegistryPostProcessor是继承了BeanFactoryPostProcessor的 List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>(); //处理容器硬编码(new 出来的)带入的beanFacotryPostProcessors //分别放入上面的相对应的集合中 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. //创建一个当前注册的RegistryProcessors的集合 List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>(); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered. //第一步:去容器中查询是否有BeanDefinitionRegistryPostProcessor类型的,实现了PriorityOrdered接口的，优先级最高 //此时ConfigurationClassPostProcessor被查询出来，ConfigurationClassPostProcessor实现了PriorityOrdered，但是优先级最低 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)); //加到已处理的list中 processedBeans.add(ppName); } } //排序当前的RegistryProcessors的集合 sortPostProcessors(currentRegistryProcessors, beanFactory); //注册RegistryProcessors的集合 registryProcessors.addAll(currentRegistryProcessors); //触发当前的registryProcessors //ConfigurationClassPostProcessor在这里会被触发 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); //清除处理过的 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,实现了Ordered接口的，优先级最高 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear. //第三步：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. //调用上面查询出来的Processor,也实现了BeanFactoryPostProcessors的接口,调用该接口的方法 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // Invoke factory processors registered with the context instance. //如果beanFactory不是BeanDefinitionRegistry的对象，直接调用BeanFactoryPostProcessor的方法 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! //下面的是处理BeanFactoryPostProcessor接口的实现类，跟上面逻辑一样，先处理实现PrioityOrdered接口的，然后再处理Ordered接口的，然后再处理普通的 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); // Separate between BeanFactoryPostProcessors that implement PriorityOrdered, // Ordered, and the rest. List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); List<String> orderedPostProcessorNames = new ArrayList<String>(); List<String> nonOrderedPostProcessorNames = new ArrayList<String>(); 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<BeanFactoryPostProcessor>(); 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<BeanFactoryPostProcessor>(); 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(); }
可以看出BeanDefinitionRegistryPostProcessor的执行时机在BeanFactoryPostProcessor之前，
两个类自己的执行首先执行PriorityOrdered修饰的，然后执行Ordered，最后执行普通的
4.3 ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry()
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); }
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) { List<BeanDefinitionHolder> configCandidates = new ArrayList<>(); //没有解析之前，系统候选的bean定义配置(有自己的配置类，还有系统自带的) 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 for (String beanName : candidateNames) { BeanDefinition beanDef = registry.getBeanDefinition(beanName); //判断是不是配置类 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 //配置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(); } // Parse each @Configuration class //创建组件扫描器 //metadataReaderFactory元数据工厂 //problemReporter问题报告器 // ConfigurationClassParser parser = new ConfigurationClassParser( this.metadataReaderFactory, this.problemReporter, this.environment, this.resourceLoader, this.componentScanBeanNameGenerator, registry); //将需要解析的类加入集合中 Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates); //创建已处理候选类集合，集合大小为候选类大小 Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size()); //循环处理候选配置类 do { //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<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()); } //@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); //清除解析过的类 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) { String[] newCandidateNames = registry.getBeanDefinitionNames(); Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames)); Set<String> alreadyParsedClasses = new HashSet<>(); for (ConfigurationClass configurationClass : alreadyParsed) { alreadyParsedClasses.add(configurationClass.getMetadata().getClassName()); } for (String candidateName : newCandidateNames) { if (!oldCandidateNames.contains(candidateName)) { BeanDefinition bd = registry.getBeanDefinition(candidateName); if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) && !alreadyParsedClasses.contains(bd.getBeanClassName())) { candidates.add(new BeanDefinitionHolder(bd, candidateName)); } } } candidateNames = newCandidateNames; } } while (!candidates.isEmpty()); // Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) { sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry()); } if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) { // Clear cache in externally provided MetadataReaderFactory; this is a no-op // for a shared cache since it'll be cleared by the ApplicationContext. ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache(); } }
4.4 ConfigurationClassParser.parse(Set<BeanDefinitionHolder> configCandidates)
public void parse(Set<BeanDefinitionHolder> configCandidates) { this.deferredImportSelectors = new LinkedList<DeferredImportSelectorHolder>(); for (BeanDefinitionHolder holder : configCandidates) { BeanDefinition bd = holder.getBeanDefinition(); try { //这里根据Bean定义的不同类型走不同的分支，但是最终都会调用到方法 //processConfigurationClass(ConfigurationClass configClass) 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); } } processDeferredImportSelectors(); }
4.4.1 ConfigurationClassParser.processConfigurationClass()
protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException { processConfigurationClass(new ConfigurationClass(metadata, beanName)); } protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
//检查当前解析的配置bean是否包含Conditional注解，如果不包含则不需要跳过
// 如果包含了则进行match方法得到匹配结果，如果是符合的并且设置的配置解析策略是解析阶段不需要调过 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); for (Iterator<ConfigurationClass> it = this.knownSuperclasses.values().iterator(); it.hasNext();) { if (configClass.equals(it.next())) { it.remove(); } } } } // Recursively process the configuration class and its superclass hierarchy. SourceClass sourceClass = asSourceClass(configClass);
//递归解析 do {
sourceClass = doProcessConfigurationClass(configClass, sourceClass); } while (sourceClass != null); // 添加到ConfigurationClassParser的configurationClasses中 this.configurationClasses.put(configClass, configClass); }
4.4.2 ConfigurationClassParser#doProcessConfigurationClass
1.处理内部类
2.处理@PropertySource注解
3.处理@ComponentScan注解
4.处理@Import注解
5.处理@ImportResource注解
6.处理@Bean修饰的方法
7.处理接口定义的方法
8.处理父类
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass) throws IOException { // Recursively process any member (nested) classes first
//处理内部类 processMemberClasses(configClass, sourceClass); // Process any @PropertySource annotations //处理@PropertySource注解 // @PropertySource注解用来加载properties文件 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"); } } // Process any @ComponentScan annotations //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) { // The config class is annotated with @ComponentScan -> perform the scan immediately 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(); } //遍历扫描到的配置类进行递归解析 if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) { parse(bdCand.getBeanClassName(), holder.getBeanName()); } } } } // Process any @Import annotations // 处理@Import注解
//这里面处理了@ImportSelector的bean定义，但是@ImportBeanDefinitionRegistar的只是将类放到了配置中 processImports(configClass, sourceClass, getImports(sourceClass), true); // Process any @ImportResource annotations // 处理@ImportResource 注解 if (sourceClass.getMetadata().isAnnotated(ImportResource.class.getName())) { AnnotationAttributes importResource = AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class); 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 //处理@Bean修饰的方法 Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass); for (MethodMetadata methodMetadata : beanMethods) {
//这里还未注册bean定义，只是将@bean修饰的方法加入配置中， configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass)); } // Process default methods on interfaces
//处理接口 processInterfaces(configClass, sourceClass); // Process superclass, if any
//处理超类 if (sourceClass.getMetadata().hasSuperClass()) { String superclass = sourceClass.getMetadata().getSuperClassName(); if (!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; }
4.4.3 ComponentScanAnnotationParser#parse
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) { // 创建 ClassPathBeanDefinitionScanner // 在 AnnotationConfigApplicationContext 的构造器中也创建了一个ClassPathBeanDefinitionScanner // 这里证明了,执行扫描 scanner 不是构造器中的,而是这里创建的 ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry, componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader); // @ComponentScan 中可以注册自定义的 BeanNameGenerator // 但是需要注意,通过源码可以明白,这里注册的自定义BeanNameGenerator 只对当前 scanner 有效 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); } // @ComponentScan(basePackageClasses = Xx.class) // 可以指定basePackageClasses, 只要是与是这几个类所在包及其子包,就可以被Spring扫描 // 经常会用一个空的类来作为basePackageClasses,默认取当前配置类所在包及其子包 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); } }); //执行扫描 return scanner.doScan(StringUtils.toStringArray(basePackages)); }
protected Set<BeanDefinitionHolder> doScan(String... basePackages) { Assert.notEmpty(basePackages, "At least one base package must be specified"); Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<BeanDefinitionHolder>(); for (String basePackage : basePackages) {
//查找包里的所有的类 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; }
4.4.4 ConfigurationClassParser.processImports
private void processImports(ConfigurationClass configClass, SourceClass currentSourceClass, Collection<SourceClass> importCandidates, boolean checkForCircularImports) { if (importCandidates.isEmpty()) { return; } if (checkForCircularImports && isChainedImportOnStack(configClass)) { this.problemReporter.error(new CircularImportProblem(configClass, this.importStack)); } else { this.importStack.push(configClass); try { for (SourceClass candidate : importCandidates) { //ImportSelector处理 if (candidate.isAssignable(ImportSelector.class)) { // Candidate class is an ImportSelector -> delegate to it to determine imports Class<?> candidateClass = candidate.loadClass(); ImportSelector selector = BeanUtils.instantiateClass(candidateClass, ImportSelector.class); ParserStrategyUtils.invokeAwareMethods( selector, this.environment, this.resourceLoader, this.registry); if (this.deferredImportSelectors != null && selector instanceof DeferredImportSelector) { this.deferredImportSelectors.add( new DeferredImportSelectorHolder(configClass, (DeferredImportSelector) selector)); } else {
//调用selectImports方法，找出需要真正导入的类 String[] importClassNames = selector.selectImports(currentSourceClass.getMetadata()); Collection<SourceClass> importSourceClasses = asSourceClasses(importClassNames);
//处理真正到要导入的类，循环处理每个bean定义 processImports(configClass, currentSourceClass, importSourceClasses, false); } } //ImportBeanDefinitionRegistrar处理 else if (candidate.isAssignable(ImportBeanDefinitionRegistrar.class)) { // Candidate class is an ImportBeanDefinitionRegistrar -> // delegate to it to register additional bean definitions Class<?> candidateClass = candidate.loadClass(); ImportBeanDefinitionRegistrar registrar = BeanUtils.instantiateClass(candidateClass, ImportBeanDefinitionRegistrar.class); ParserStrategyUtils.invokeAwareMethods( registrar, this.environment, this.resourceLoader, this.registry);
//这里并未处理，只是将ImportBeanDefinitionRegistrar的实现类加入配置中，接着往下看，是否会调用他的registerBeanDefinitions方法导入bean定义
//事实上是在this.reader.loadBeanDefinitions(configClasses)中处理 configClass.addImportBeanDefinitionRegistrar(registrar, currentSourceClass.getMetadata()); } //导入普通类的处理 else { // Candidate class not an ImportSelector or ImportBeanDefinitionRegistrar -> // process it as an @Configuration class this.importStack.registerImport( currentSourceClass.getMetadata(), candidate.getMetadata().getClassName()); processConfigurationClass(candidate.asConfigClass(configClass)); } } } catch (BeanDefinitionStoreException ex) { throw ex; } catch (Throwable ex) { throw new BeanDefinitionStoreException( "Failed to process import candidates for configuration class [" + configClass.getMetadata().getClassName() + "]", ex); } finally { this.importStack.pop(); } } }
4.5 this.reader.loadBeanDefinitions(configClasses);
4.3分析了parse方法， 但是可以看出来上面@ImportBeanDefinitionRegistrar和@Bean和@ImportResource犯法的bean定义并未注册，只是讲这些配置放到了成员变量中，这些bean定义都是在ader.loadBeanDefinitions中注册的，继续往下分析
public void loadBeanDefinitions(Set<ConfigurationClass> configurationModel) { TrackedConditionEvaluator trackedConditionEvaluator = new TrackedConditionEvaluator(); for (ConfigurationClass configClass : configurationModel) { loadBeanDefinitionsForConfigurationClass(configClass, trackedConditionEvaluator); } }
private void loadBeanDefinitionsForConfigurationClass( ConfigurationClass configClass, TrackedConditionEvaluator trackedConditionEvaluator) { if (trackedConditionEvaluator.shouldSkip(configClass)) { String beanName = configClass.getBeanName(); if (StringUtils.hasLength(beanName) && this.registry.containsBeanDefinition(beanName)) { this.registry.removeBeanDefinition(beanName); } this.importRegistry.removeImportingClass(configClass.getMetadata().getClassName()); return; } //判断主配置类是不是Improt导入的 if (configClass.isImported()) { registerBeanDefinitionForImportedConfigurationClass(configClass); }
//处理@Bean的bean定义 for (BeanMethod beanMethod : configClass.getBeanMethods()) { loadBeanDefinitionsForBeanMethod(beanMethod); } //处理@ImportResource配置的bean定义 loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
//处理@ImportBeanDefinitionRegistrar的bean定义 loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars()); }
