好久没更新了，年末最初一个季度的确会比较忙，也是抽空看完了 Spring 的源码，这里进行一下回顾总结，当初 Spring 的源码切实太多，有的剖析的也很粗疏，这里就不打算剖析的太细了。还是依照之前的节奏，依照我看源码的几个点进行剖析。如果有什么问题，还心愿多多指教。上面开始源码剖析

Spring 置信大家都用的最多的框架了，基本功能也都理解，这里就做过多介绍了（别问，问就是懒～）。咱们直切主题。反正我困惑的就几个点

• IoC 是怎么获取 bean 信息，并治理 bean 的

• IoC 引以为豪的依赖注入

  • IoC 是怎么解决循环依赖的（没错齐全是因为网上说面试爱问）

  上面就针对这几个问题来看。

后期筹备

环境筹备

jdk:1.8

官网我的项目地址:https://github.com/spring-pro…

集体 gitee 地址：https://gitee.com/Nortyr/spri…

分支：self_note 原分支：5.2.x

测试代码

跟踪原始代码是通过传统的 xml 配置的形式，所以本篇以 xml 的形式为主，然而当初应该大多数都实用注解配置了，最初会解说下注解和 xml 的异同（就是扫描的形式不同）。

传统 spring 写法

public class Son {public void say(){System.out.println("say hello!");
   }
}

public class Father {
   private Son son;

   public void say(){son.say();
   }

   public void setSon(Son son) {}}

public class Demo {public static void main(String[] args) {AbstractApplicationContext context = new ClassPathXmlApplicationContext("lifecycleTests2.xml",Demo.class);
      Father father=(Father) context.getBean("father");
      father.say();}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans-2.0.xsd">


   <bean id="son" class="org.springframework.test.self.xml2.Son" />
   <bean id="father" class="org.springframework.test.self.xml2.Father" >
      <property name="son" ref="son"/>
   </bean>

</beans>

注解版本

@Component
public class Son {public void say(){System.out.println("abcdefg");
   }
}

@Component
public class Father {
   @Autowired
   private Son son;

   public void say(){son.say();
      System.out.println("say hello");
   }
}

@ComponentScan("org.springframework.test.self.annotation")
public class Demo {public static void main(String[] args) {AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
      applicationContext.register(Demo.class);
      applicationContext.refresh();
      Father bean = (Father) applicationContext.getBean("father");
      bean.say();}
}

IoC 如何获取 Bean

依据 mybatis 的教训，必定就是到哪个中央解析 xml，并生成对应的对象，而后依据配置，生成对应的类。spring 解析也差不多这样

public ClassPathXmlApplicationContext(String[] paths, Class<?> clazz, @Nullable ApplicationContext parent)
      throws BeansException {super(parent);
   Assert.notNull(paths, "Path array must not be null");
   Assert.notNull(clazz, "Class argument must not be null");
   this.configResources = new Resource[paths.length];
   for (int i = 0; i < paths.length; i++) {this.configResources[i] = new ClassPathResource(paths[i], clazz);
   }
   // 初始化容器
   refresh();}

上面就进入到 ioc 外围，refresh()办法。

@Override
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {
      // Prepare this context for refreshing.
      // 筹备此上下文以进行刷新，各种初始化配置
      prepareRefresh();

      // Tell the subclass to refresh the internal bean factory.
      // 调用 refreshBeanFactory()，通过 createBeanFactory 结构了一个 ApplicationContext(DefaultApplicationContext)
      // 同时启动了 loadBeanDefinitions 来载入 BeanDefinition
      // 通知子类刷新外部 bean 工厂。ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

      // Prepare the bean factory for use in this context.
      // 筹备在此上下文中应用的 beanFactory，配置零碎默认的一些 bean
      prepareBeanFactory(beanFactory);

      try {
         // Allows post-processing of the bean factory in context subclasses.
         // 设置 BeanFactory 的后置解决
         postProcessBeanFactory(beanFactory);

         // Invoke factory processors registered as beans in the context.
         // 调用在上下文中注册为 beanFactory 的后置处理器。invokeBeanFactoryPostProcessors(beanFactory);

         // Register bean processors that intercept bean creation.
         // 注册 bean 的后处理器，在 bean 创立的过程中调用
         registerBeanPostProcessors(beanFactory);

         // Initialize message source for this context.
         // 初始化此上下文的音讯源
         initMessageSource();

         // Initialize event multicaster for this context.
         // 为此上下文初始化事件机制
         initApplicationEventMulticaster();

         // Initialize other special beans in specific context subclasses.
         // 初始化特定上下文子类中的其余非凡 bean。onRefresh();

         // Check for listener beans and register them.
         // 查看侦听 bean 并注册它们。registerListeners();

         // Instantiate all remaining (non-lazy-init) singletons.
         // 实例化所有残余的（非提早初始化）单例。finishBeanFactoryInitialization(beanFactory);

         // Last step: publish corresponding event.
         // 最初一步：公布相应的事件。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.|销毁曾经创立的单例以防止悬空资源。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...
         // 重置 Spring 外围中的常见内省缓存，因为咱们可能不再须要单例 bean 的元数据......
         resetCommonCaches();}
   }
}

本次解析的过程就是在这个办法中实现ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {refreshBeanFactory();
   return getBeanFactory();}

AbstractRefreshableApplicationContext#refreshBeanFactory外围就是这个办法，它创立了 BeanFactory，BeanFactory 就能够了解为 IoC 容器，封装了根本的办法。在各种ApplicationContext 例如ClassPathXmlApplicationContext，`
AnnotationConfigApplicationContext` 中的具体实现也是通过 BeanFactory

/**
 * This implementation performs an actual refresh of this context's underlying
 * bean factory, shutting down the previous bean factory (if any) and
 * initializing a fresh bean factory for the next phase of the context's lifecycle.
 * 此实现执行此上下文的底层 bean 工厂的理论刷新，敞开先前的 bean 工厂（如果有）并为上下文生命周期的下一个阶段初始化一个新的 bean 工厂。*/
@Override
protected final void refreshBeanFactory() throws BeansException {if (hasBeanFactory()) {// 如果有就销毁
      destroyBeans();
      closeBeanFactory();}
   try {
      // 创立 DefaultListableBeanFactory
      DefaultListableBeanFactory beanFactory = createBeanFactory();
      beanFactory.setSerializationId(getId());
      customizeBeanFactory(beanFactory);
      // 载入 BeanDefinition 信息，应用 BeanDefinitionReader
      loadBeanDefinitions(beanFactory);
      this.beanFactory = beanFactory;
   }
   catch (IOException ex) {throw new ApplicationContextException("I/O error parsing bean definition source for" + getDisplayName(), ex);
   }
}

上面就进入 bean 的解析了，这里你就能够看到和 MyBatis 解析的差不多，创立一个对象，解析 xml，最终后果都差不多，这里就不深刻了，喜爱的能够看后面的万字整顿 MyBatis 源码

@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
   // Create a new XmlBeanDefinitionReader for the given BeanFactory.|为给定的 BeanFactory 创立一个新的 XmlBeanDefinitionReader。XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);

   // Configure the bean definition reader with this context's
   // resource loading environment.
   beanDefinitionReader.setEnvironment(this.getEnvironment());
   beanDefinitionReader.setResourceLoader(this);
   beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));

   // Allow a subclass to provide custom initialization of the reader,
   // then proceed with actually loading the bean definitions.
   initBeanDefinitionReader(beanDefinitionReader);
   loadBeanDefinitions(beanDefinitionReader);
}

最初在 XmlBeanDefinitionReader#doLoadBeanDefinitions 中解析 xml

protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
      throws BeanDefinitionStoreException {

   try {Document doc = doLoadDocument(inputSource, resource);
      int count = registerBeanDefinitions(doc, resource);// 对 BeanDefinition 解析的具体过程，这个解析会应用到 Spring 的 Bean 配置规定
      if (logger.isDebugEnabled()) {logger.debug("Loaded" + count + "bean definitions from" + resource);
      }
      return count;
   }
   ...catch 略
}

接着就会解析各个节点，而后进入 DefaultBeanDefinitionDocumentReader#processBeanDefinition 进行解析

/** 解决给定的 bean 元素，解析 bean 定义并将其注册到注册表。* Process the given bean element, parsing the bean definition
 * and registering it with the registry.
 */
protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
   // 具体解决委托给 BeanDefinitionParserDelegate 实现
   // 创立 GenericBeanDefinition，设置属性，解析 xml 各个属性封装进 BeanDefinitionHolder
   BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
   if (bdHolder != null) {
      // 解析自定义标签
      bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
      try {
         // 注册解析失去的 BeanDefinition
         BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
      }
      catch (BeanDefinitionStoreException ex) {getReaderContext().error("Failed to register bean definition with name'" +
               bdHolder.getBeanName() + "'", ele, ex);
      }
      // 在 BeanDefinition 向 IOC 容器注册实现当前，发送音讯
      getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
   }
}

这个 BeanDefinitionHolder 就是封装了 BeanDefinition 和 bean 名称与别名

public class BeanDefinitionHolder implements BeanMetadataElement {

   private final BeanDefinition beanDefinition;

   private final String beanName;

   @Nullable
   private final String[] aliases;
   //... 其余略
}

BeanDefinition是个啥呢, 能够看下接口规定的一些属性，这些属性基本上就是 xml 定义的 bean 标签的各种属性，相当于对应了每一个 bean 标签，解析过程如下（和 mybatis 很相似，略微看看就行了）

解析过程也如下所示（BeanDefinitionParserDelegate#parseBeanDefinitionElement(Element,、String, BeanDefinition)）

@Nullable
public AbstractBeanDefinition parseBeanDefinitionElement(Element ele, String beanName, @Nullable BeanDefinition containingBean) {this.parseState.push(new BeanEntry(beanName));

   String className = null;
   if (ele.hasAttribute(CLASS_ATTRIBUTE)) {className = ele.getAttribute(CLASS_ATTRIBUTE).trim();}
   String parent = null;
   if (ele.hasAttribute(PARENT_ATTRIBUTE)) {parent = ele.getAttribute(PARENT_ATTRIBUTE);
   }

   try {AbstractBeanDefinition bd = createBeanDefinition(className, parent);
      // 解析各个 xml 属性，并设置进 beanDefinition
      parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);
      bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));

      parseMetaElements(ele, bd);
      parseLookupOverrideSubElements(ele, bd.getMethodOverrides());
      parseReplacedMethodSubElements(ele, bd.getMethodOverrides());

      parseConstructorArgElements(ele, bd);
      parsePropertyElements(ele, bd);
      parseQualifierElements(ele, bd);

      bd.setResource(this.readerContext.getResource());
      bd.setSource(extractSource(ele));

      return bd;
   }
  ...catch 略过

   return null;
}

public AbstractBeanDefinition parseBeanDefinitionAttributes(Element ele, String beanName,
      @Nullable BeanDefinition containingBean, AbstractBeanDefinition bd) {if (ele.hasAttribute(SINGLETON_ATTRIBUTE)) {error("Old 1.x'singleton'attribute in use - upgrade to'scope'declaration", ele);
   }
   else if (ele.hasAttribute(SCOPE_ATTRIBUTE)) {bd.setScope(ele.getAttribute(SCOPE_ATTRIBUTE));
   }
   else if (containingBean != null) {
      // Take default from containing bean in case of an inner bean definition.
      bd.setScope(containingBean.getScope());
   }

   if (ele.hasAttribute(ABSTRACT_ATTRIBUTE)) {bd.setAbstract(TRUE_VALUE.equals(ele.getAttribute(ABSTRACT_ATTRIBUTE)));
   }

   String lazyInit = ele.getAttribute(LAZY_INIT_ATTRIBUTE);
   if (isDefaultValue(lazyInit)) {lazyInit = this.defaults.getLazyInit();
   }
   bd.setLazyInit(TRUE_VALUE.equals(lazyInit));

   String autowire = ele.getAttribute(AUTOWIRE_ATTRIBUTE);
   bd.setAutowireMode(getAutowireMode(autowire));

   if (ele.hasAttribute(DEPENDS_ON_ATTRIBUTE)) {String dependsOn = ele.getAttribute(DEPENDS_ON_ATTRIBUTE);
      bd.setDependsOn(StringUtils.tokenizeToStringArray(dependsOn, MULTI_VALUE_ATTRIBUTE_DELIMITERS));
   }

   String autowireCandidate = ele.getAttribute(AUTOWIRE_CANDIDATE_ATTRIBUTE);
   if (isDefaultValue(autowireCandidate)) {String candidatePattern = this.defaults.getAutowireCandidates();
      if (candidatePattern != null) {String[] patterns = StringUtils.commaDelimitedListToStringArray(candidatePattern);
         bd.setAutowireCandidate(PatternMatchUtils.simpleMatch(patterns, beanName));
      }
   }
   else {bd.setAutowireCandidate(TRUE_VALUE.equals(autowireCandidate));
   }

   ...ifelse 属性填充掠过

   return bd;
}

解析实现之后呢，就进入了

// 注册解析失去的 BeanDefinition
BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());

最初会在 DefaultListableBeanFactory#registerBeanDefinition 注册 bean。也就是把 Bean 和 BeanDefinition 对应关系增加进 `
DefaultListableBeanFactory::beanDefinitionMap，beanName 增加进 DefaultListableBeanFactory::beanDefinitionNames `
别名和 beanName 的对应关系增加进SimpleAliasRegistry::aliasMap

@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
      throws BeanDefinitionStoreException {Assert.hasText(beanName, "Bean name must not be empty");
   Assert.notNull(beanDefinition, "BeanDefinition must not be null");

   if (beanDefinition instanceof AbstractBeanDefinition) {
      try {((AbstractBeanDefinition) beanDefinition).validate();}
      catch (BeanDefinitionValidationException ex) {throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
               "Validation of bean definition failed", ex);
      }
   }
   // 查看是否有同名的 bean
   BeanDefinition existingDefinition = this.beanDefinitionMap.get(beanName);
   if (existingDefinition != null) {if (!isAllowBeanDefinitionOverriding()) {throw new BeanDefinitionOverrideException(beanName, beanDefinition, existingDefinition);
      }
      else if (existingDefinition.getRole() < beanDefinition.getRole()) {
         // e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE
         if (logger.isInfoEnabled()) {
            logger.info("Overriding user-defined bean definition for bean'" + beanName +
                  "'with a framework-generated bean definition: replacing [" +
                  existingDefinition + "] with [" + beanDefinition + "]");
         }
      }
      else if (!beanDefinition.equals(existingDefinition)) {if (logger.isDebugEnabled()) {
            logger.debug("Overriding bean definition for bean'" + beanName +
                  "'with a different definition: replacing [" + existingDefinition +
                  "] with [" + beanDefinition + "]");
         }
      }
      else {if (logger.isTraceEnabled()) {
            logger.trace("Overriding bean definition for bean'" + beanName +
                  "'with an equivalent definition: replacing [" + existingDefinition +
                  "] with [" + beanDefinition + "]");
         }
      }
      this.beanDefinitionMap.put(beanName, beanDefinition);
   }
   else {if (hasBeanCreationStarted()) {// Cannot modify startup-time collection elements anymore (for stable iteration)
         synchronized (this.beanDefinitionMap) {this.beanDefinitionMap.put(beanName, beanDefinition);
            List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
            updatedDefinitions.addAll(this.beanDefinitionNames);
            updatedDefinitions.add(beanName);
            this.beanDefinitionNames = updatedDefinitions;
            removeManualSingletonName(beanName);
         }
      }
      else {// 将 bean 增加进 this.beanDefinitionMap，beanName 增加进 beanDefinitionNames
         // Still in startup registration phase|仍处于启动注册阶段
         this.beanDefinitionMap.put(beanName, beanDefinition);
         this.beanDefinitionNames.add(beanName);
         removeManualSingletonName(beanName);
      }
      this.frozenBeanDefinitionNames = null;
   }

   if (existingDefinition != null || containsSingleton(beanName)) {resetBeanDefinition(beanName);
   }
   else if (isConfigurationFrozen()) {clearByTypeCache();
   }
}

至此，bean 解析就完了（解析过程还真是千篇一律）
上面咱们来看看 bean 解析的形式
在类上定义了 @ComponentScan("org.springframework.test.self.annotation") 那大略就是扫描包下的所有文件了

@ComponentScan("org.springframework.test.self.annotation")
public class Demo {public static void main(String[] args) {AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
      applicationContext.register(Demo.class);
      applicationContext.refresh();
      Father bean = (Father) applicationContext.getBean("father");
      bean.say();}
}

解析也不是在 ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); 中完了，而是在 invokeBeanFactoryPostProcessors 中实现

@Override
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {
         ... 略
         // Invoke factory processors registered as beans in the context.
         // 调用在上下文中注册为 beanFactory 的后置处理器。invokeBeanFactoryPostProcessors(beanFactory);
         ... 略
   }
}   

ConfigurationClassParser#doProcessConfigurationClass

@Nullable
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass, Predicate<String> filter)
      throws IOException {if (configClass.getMetadata().isAnnotated(Component.class.getName())) {// Recursively process any member (nested) classes first| 首先递归解决任何成员（嵌套）类
      processMemberClasses(configClass, sourceClass, filter);
   }

   // 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 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 配置类应用 @ComponentScan 注解 -> 立刻执行扫描, 在这一步进行扫描
         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());
            }
         }
      }
   }

   // Process any @Import annotations
   processImports(configClass, sourceClass, getImports(sourceClass), filter, true);

   // Process any @ImportResource annotations
   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
   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;
}

而后就是层层解析，找到合乎的 class 文件

private Set<BeanDefinition> scanCandidateComponents(String basePackage) {Set<BeanDefinition> candidates = new LinkedHashSet<>();
   try {
      String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
            resolveBasePackage(basePackage) + '/' + this.resourcePattern;
      //TODO 重要注解扫描某个包下的所有文件
      Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
      boolean traceEnabled = logger.isTraceEnabled();
      boolean debugEnabled = logger.isDebugEnabled();
      for (Resource resource : resources) {if (traceEnabled) {logger.trace("Scanning" + resource);
         }
         try {MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
            if (isCandidateComponent(metadataReader)) {ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
               sbd.setSource(resource);
               if (isCandidateComponent(sbd)) {if (debugEnabled) {logger.debug("Identified candidate component class:" + resource);
                  }
                  candidates.add(sbd);
               }
               else {if (debugEnabled) {logger.debug("Ignored because not a concrete top-level class:" + resource);
                  }
               }
            }
            else {if (traceEnabled) {logger.trace("Ignored because not matching any filter:" + resource);
               }
            }
         }
         catch (FileNotFoundException ex) {if (traceEnabled) {logger.trace("Ignored non-readable" + resource + ":" + ex.getMessage());
            }
         }
         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;
}

生成ScannedGenericBeanDefinition

前面就差不多一样了，把 Bean 和 BeanDefinition 对应关系增加进 `
DefaultListableBeanFactory::beanDefinitionMap，beanName 增加进DefaultListableBeanFactory::beanDefinitionNames `

总结

总结一下 spring 解析的大体流程：

• 寻找：

  • xml：解析配置，生成对应的对象。
  • 注解，找到后期注册进上下文中的类，循环找到对应的 @ComponentScan 注解找到包下的所有类
• bean 解析：获取到对应的配置信息，封装进 BeanDefinition,(xml:GenericBeanDefinition, 注解:ScannedGenericBeanDefinition)

• 注册:

  • Bean 和 BeanDefinition 对应关系增加进DefaultListableBeanFactory::beanDefinitionMap
  • beanName 增加进DefaultListableBeanFactory::beanDefinitionNames