springboot源码(二)：自动装配原理
在之前的课程中我们讲解了springboot的启动过程，其实在面试过程中问的最多的可能是自动装配的原理，而自动装配是在启动过程中完成，只不过在刚开始的时候我们选择性的跳过了，下面详细讲解自动装配的过程。
1、在springboot的启动过程中，有一个步骤是创建上下文，如果不记得可以看下面的代码：
public ConfigurableApplicationContext run(String... args) {StopWatch stopWatch = new StopWatch();stopWatch.start();ConfigurableApplicationContext context = null;Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();configureHeadlessProperty();SpringApplicationRunListeners listeners = getRunListeners(args);listeners.starting();try {ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);configureIgnoreBeanInfo(environment);Banner printedBanner = printBanner(environment);context = createApplicationContext();exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,new Class[] { ConfigurableApplicationContext.class }, context);//此处完成自动装配的过程prepareContext(context, environment, listeners, applicationArguments, printedBanner);refreshContext(context);afterRefresh(context, applicationArguments);stopWatch.stop();if (this.logStartupInfo) {new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);}listeners.started(context);callRunners(context, applicationArguments);}catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, listeners);throw new IllegalStateException(ex);}try {listeners.running(context);}catch (Throwable ex) {handleRunFailure(context, ex, exceptionReporters, null);throw new IllegalStateException(ex);}return context;}
2、在prepareContext方法中查找load方法，一层一层向内点击，找到最终的load方法
//prepareContext方法private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {context.setEnvironment(environment);postProcessApplicationContext(context);applyInitializers(context);listeners.contextPrepared(context);if (this.logStartupInfo) {logStartupInfo(context.getParent() == null);logStartupProfileInfo(context);}// Add boot specific singleton beansConfigurableListableBeanFactory beanFactory = context.getBeanFactory();beanFactory.registerSingleton("springApplicationArguments", applicationArguments);if (printedBanner != null) {beanFactory.registerSingleton("springBootBanner", printedBanner);}if (beanFactory instanceof DefaultListableBeanFactory) {((DefaultListableBeanFactory) beanFactory).setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);}if (this.lazyInitialization) {context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());}// Load the sourcesSet<Object> sources = getAllSources();Assert.notEmpty(sources, "Sources must not be empty");//load方法完成该功能load(context, sources.toArray(new Object[0]));listeners.contextLoaded(context);}/*** Load beans into the application context.* @param context the context to load beans into* @param sources the sources to load* 加载bean对象到context中*/protected void load(ApplicationContext context, Object[] sources) {if (logger.isDebugEnabled()) {logger.debug("Loading source " + StringUtils.arrayToCommaDelimitedString(sources));}//获取bean对象定义的加载器BeanDefinitionLoader loader = createBeanDefinitionLoader(getBeanDefinitionRegistry(context), sources);if (this.beanNameGenerator != null) {loader.setBeanNameGenerator(this.beanNameGenerator);}if (this.resourceLoader != null) {loader.setResourceLoader(this.resourceLoader);}if (this.environment != null) {loader.setEnvironment(this.environment);}loader.load();}/*** Load the sources into the reader.* @return the number of loaded beans*/int load() {int count = 0;for (Object source : this.sources) {count += load(source);}return count;}
3、实际执行load的是BeanDefinitionLoader中的load方法，如下：
//实际记载bean的方法private int load(Object source) {Assert.notNull(source, "Source must not be null");//如果是class类型，启用注解类型if (source instanceof Class<?>) {return load((Class<?>) source);}//如果是resource类型，启动xml解析if (source instanceof Resource) {return load((Resource) source);}//如果是package类型，启用扫描包，例如@ComponentScanif (source instanceof Package) {return load((Package) source);}//如果是字符串类型，直接加载if (source instanceof CharSequence) {return load((CharSequence) source);}throw new IllegalArgumentException("Invalid source type " + source.getClass());}
4、下面方法将用来判断是否资源的类型，是使用groovy加载还是使用注解的方式
private int load(Class<?> source) {//判断使用groovy脚本if (isGroovyPresent() && GroovyBeanDefinitionSource.class.isAssignableFrom(source)) {// Any GroovyLoaders added in beans{} DSL can contribute beans hereGroovyBeanDefinitionSource loader = BeanUtils.instantiateClass(source, GroovyBeanDefinitionSource.class);load(loader);}//使用注解加载if (isComponent(source)) {this.annotatedReader.register(source);return 1;}return 0;}
5、下面方法判断启动类中是否包含@Component注解，但是会神奇的发现我们的启动类中并没有该注解，继续更进发现MergedAnnotations类传入了一个参数SearchStrategy.TYPE_HIERARCHY，会查找继承关系中是否包含这个注解，@SpringBootApplication–>@SpringBootConfiguration–>@Configuration–>@Component,当找到@Component注解之后，会把该对象注册到AnnotatedBeanDefinitionReader对象中
private boolean isComponent(Class<?> type) {// This has to be a bit of a guess. The only way to be sure that this type is// eligible is to make a bean definition out of it and try to instantiate it.if (MergedAnnotations.from(type, SearchStrategy.TYPE_HIERARCHY).isPresent(Component.class)) {return true;}// Nested anonymous classes are not eligible for registration, nor are groovy// closuresreturn !type.getName().matches(".*\\$_.*closure.*") && !type.isAnonymousClass()&& type.getConstructors() != null && type.getConstructors().length != 0;
}/*** Register a bean from the given bean class, deriving its metadata from* class-declared annotations.* 从给定的bean class中注册一个bean对象，从注解中找到相关的元数据*/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);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));}}}if (customizers != null) {for (BeanDefinitionCustomizer customizer : customizers) {customizer.customize(abd);}}BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);}/*** Register the given bean definition with the given bean factory.* 注册主类，如果有别名可以设置别名*/public static void registerBeanDefinition(BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)throws BeanDefinitionStoreException {// Register bean definition under primary name.String beanName = definitionHolder.getBeanName();registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());// Register aliases for bean name, if any.String[] aliases = definitionHolder.getAliases();if (aliases != null) {for (String alias : aliases) {registry.registerAlias(beanName, alias);}}}//@SpringBootApplication
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {}//@SpringBootConfiguration
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Configuration
public @interface SpringBootConfiguration {}//@Configuration
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Configuration {}
当看完上述代码之后，只是完成了启动对象的注入，自动装配还没有开始，下面开始进入到自动装配。
6、自动装配入口，从刷新容器开始
@Overridepublic 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.// 此处是自动装配的入口invokeBeanFactoryPostProcessors(beanFactory);}
7、在invokeBeanFactoryPostProcessors方法中完成bean的实例化和执行
/*** Instantiate and invoke all registered BeanFactoryPostProcessor beans,* respecting explicit order if given.* <p>Must be called before singleton instantiation.*/protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {//开始执行beanFactoryPostProcessor对应实现类,需要知道的是beanFactoryPostProcessor是spring的扩展接口，在刷新容器之前，该接口可以用来修改bean元数据信息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()));}}
8、查看invokeBeanFactoryPostProcessors的具体执行方法
public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {// Invoke BeanDefinitionRegistryPostProcessors first, if any.Set<String> processedBeans = new HashSet<>();if (beanFactory instanceof BeanDefinitionRegistry) {BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();//开始遍历三个内部类，如果属于BeanDefinitionRegistryPostProcessor子类，加入到bean注册的集合，否则加入到regularPostProcessorsfor (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.//通过BeanDefinitionRegistryPostProcessor获取到对应的处理类“org.springframework.context.annotation.internalConfigurationAnnotationProcessor”，但是需要注意的是这个类在springboot中搜索不到，这个类的完全限定名在AnnotationConfigEmbeddedWebApplicationContext中，在进行初始化的时候会装配几个类，在创建AnnotatedBeanDefinitionReader对象的时候会将该类注册到bean对象中，此处可以看到internalConfigurationAnnotationProcessor为bean名称，容器中真正的类是ConfigurationClassPostProcessorString[] postProcessorNames =beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);//首先执行类型为PriorityOrdered的BeanDefinitionRegistryPostProcessor//PriorityOrdered类型表明为优先执行for (String ppName : postProcessorNames) {if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {//获取对应的beancurrentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));//用来存储已经执行过的BeanDefinitionRegistryPostProcessorprocessedBeans.add(ppName);}}sortPostProcessors(currentRegistryProcessors, beanFactory);registryProcessors.addAll(currentRegistryProcessors);//开始执行装配逻辑invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.//其次执行类型为Ordered的BeanDefinitionRegistryPostProcessor//Ordered表明按顺序执行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.//循环中执行类型不为PriorityOrdered，Ordered类型的BeanDefinitionRegistryPostProcessorboolean 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. //执行父类方法，优先执行注册处理类invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);//执行有规则处理类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();}
9、开始执行自动配置逻辑（启动类指定的配置，非默认配置），可以通过debug的方式一层层向里进行查找，会发现最终会在ConfigurationClassParser类中，此类是所有配置类的解析类，所有的解析逻辑在parser.parse(candidates)中
public void parse(Set<BeanDefinitionHolder> configCandidates) {for (BeanDefinitionHolder holder : configCandidates) {BeanDefinition bd = holder.getBeanDefinition();try {//是否是注解类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);}}//执行配置类this.deferredImportSelectorHandler.process();}
-------------------protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {processConfigurationClass(new ConfigurationClass(metadata, beanName));}
-------------------protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {return;}ConfigurationClass existingClass = this.configurationClasses.get(configClass);if (existingClass != null) {if (configClass.isImported()) {if (existingClass.isImported()) {existingClass.mergeImportedBy(configClass);}// Otherwise ignore new imported config class; existing non-imported class overrides it.return;}else {// Explicit bean definition found, probably replacing an import.// Let's remove the old one and go with the new one.this.configurationClasses.remove(configClass);this.knownSuperclasses.values().removeIf(configClass::equals);}}// Recursively process the configuration class and its superclass hierarchy.SourceClass sourceClass = asSourceClass(configClass);do {//循环处理bean,如果有父类，则处理父类，直至结束sourceClass = doProcessConfigurationClass(configClass, sourceClass);}while (sourceClass != null);this.configurationClasses.put(configClass, configClass);}
10、继续跟进doProcessConfigurationClass方法，此方式是支持注解配置的核心逻辑
/*** 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.* @param configClass the configuration class being build* @param sourceClass a source class* @return the superclass, or {@code null} if none found or previously processed*/@Nullableprotected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)throws IOException {//处理内部类逻辑，由于传来的参数是启动类，并不包含内部类，所以跳过if (configClass.getMetadata().isAnnotated(Component.class.getName())) {// Recursively process any member (nested) classes firstprocessMemberClasses(configClass, sourceClass);}// Process any @PropertySource annotations//针对属性配置的解析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 any @ComponentScan annotations// 这里是根据启动类@ComponentScan注解来扫描项目中的beanSet<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//遍历项目中的bean，如果是注解定义的bean，则进一步解析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 neededfor (BeanDefinitionHolder holder : scannedBeanDefinitions) {BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();if (bdCand == null) {bdCand = holder.getBeanDefinition();}if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {//递归解析，所有的bean,如果有注解，会进一步解析注解中包含的beanparse(bdCand.getBeanClassName(), holder.getBeanName());}}}}// Process any @Import annotations//递归解析，获取导入的配置类，很多情况下，导入的配置类中会同样包含导入类注解processImports(configClass, sourceClass, getImports(sourceClass), true);// Process any @ImportResource annotations//解析@ImportResource配置类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//处理@Bean注解修饰的类Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);for (MethodMetadata methodMetadata : beanMethods) {configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));}// Process default methods on interfaces// 处理接口中的默认方法processInterfaces(configClass, sourceClass);// Process superclass, if any//如果该类有父类，则继续返回，上层方法判断不为空，则继续递归执行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 recursereturn sourceClass.getSuperClass();}}// No superclass -> processing is completereturn null;}11、查看获取配置类的逻辑
processImports(configClass, sourceClass, getImports(sourceClass), true);/*** Returns {@code @Import} class, considering all meta-annotations.*/private Set<SourceClass> getImports(SourceClass sourceClass) throws IOException {Set<SourceClass> imports = new LinkedHashSet<>();Set<SourceClass> visited = new LinkedHashSet<>();collectImports(sourceClass, imports, visited);return imports;}
------------------/*** Recursively collect all declared {@code @Import} values. Unlike most* meta-annotations it is valid to have several {@code @Import}s declared with* different values; the usual process of returning values from the first* meta-annotation on a class is not sufficient.* <p>For example, it is common for a {@code @Configuration} class to declare direct* {@code @Import}s in addition to meta-imports originating from an {@code @Enable}* annotation.* 看到所有的bean都以导入的方式被加载进去*/private void collectImports(SourceClass sourceClass, Set<SourceClass> imports, Set<SourceClass> visited)throws IOException {if (visited.add(sourceClass)) {for (SourceClass annotation : sourceClass.getAnnotations()) {String annName = annotation.getMetadata().getClassName();if (!annName.equals(Import.class.getName())) {collectImports(annotation, imports, visited);}}imports.addAll(sourceClass.getAnnotationAttributes(Import.class.getName(), "value"));}}
12、继续回到ConfigurationClassParser中的parse方法中的最后一行,继续跟进该方法：
this.deferredImportSelectorHandler.process()
-------------
public void process() {List<DeferredImportSelectorHolder> deferredImports = this.deferredImportSelectors;this.deferredImportSelectors = null;try {if (deferredImports != null) {DeferredImportSelectorGroupingHandler handler = new DeferredImportSelectorGroupingHandler();deferredImports.sort(DEFERRED_IMPORT_COMPARATOR);deferredImports.forEach(handler::register);handler.processGroupImports();}}finally {this.deferredImportSelectors = new ArrayList<>();}}
---------------public void processGroupImports() {for (DeferredImportSelectorGrouping grouping : this.groupings.values()) {grouping.getImports().forEach(entry -> {ConfigurationClass configurationClass = this.configurationClasses.get(entry.getMetadata());try {processImports(configurationClass, asSourceClass(configurationClass),asSourceClasses(entry.getImportClassName()), false);}catch (BeanDefinitionStoreException ex) {throw ex;}catch (Throwable ex) {throw new BeanDefinitionStoreException("Failed to process import candidates for configuration class [" +configurationClass.getMetadata().getClassName() + "]", ex);}});}}
------------/*** Return the imports defined by the group.* @return each import with its associated configuration class*/public Iterable<Group.Entry> getImports() {for (DeferredImportSelectorHolder deferredImport : this.deferredImports) {this.group.process(deferredImport.getConfigurationClass().getMetadata(),deferredImport.getImportSelector());}return this.group.selectImports();}}
------------public DeferredImportSelector getImportSelector() {return this.importSelector;}
------------@Overridepublic void process(AnnotationMetadata annotationMetadata, DeferredImportSelector deferredImportSelector) {Assert.state(deferredImportSelector instanceof AutoConfigurationImportSelector,() -> String.format("Only %s implementations are supported, got %s",AutoConfigurationImportSelector.class.getSimpleName(),deferredImportSelector.getClass().getName()));AutoConfigurationEntry autoConfigurationEntry = ((AutoConfigurationImportSelector) deferredImportSelector).getAutoConfigurationEntry(getAutoConfigurationMetadata(), annotationMetadata);this.autoConfigurationEntries.add(autoConfigurationEntry);for (String importClassName : autoConfigurationEntry.getConfigurations()) {this.entries.putIfAbsent(importClassName, annotationMetadata);}}
