spring boot 源码解析11-ConfigurationClassPostProcessor类加载解析

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前言

ConfigurationClassPostProcessor实现了BeanDefinitionRegistryPostProcessor接口,该类会在AbstractApplicationContext#refresh 中的第5步时进行调用.由于其postProcessBeanDefinitionRegistry 实现过程非常复杂,因此单拿一篇进行分析

解析

ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry 代码如下:

    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);
        }

2件事

  1. 根据BeanDefinitionRegistry,生成registryId 加入到registriesPostProcessed中.registriesPostProcessed是为了做去重的判断,当重复对一个BeanDefinitionRegistry进行处理时,则会抛出IllegalStateException.
  2. 调用processConfigBeanDefinitions 进行类的加载.代码如下:

        public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
            List configCandidates = new ArrayList();
            // 1. 获取已经注册的bean名称
            String[] candidateNames = registry.getBeanDefinitionNames();
    
            for (String beanName : candidateNames) {
                BeanDefinition beanDef = registry.getBeanDefinition(beanName);
                if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
                        ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
                    // 1.1. 如果BeanDefinition 中的configurationClass 属性为full 或者lite ,则意味着已经处理过了,直接跳过
                    if (logger.isDebugEnabled()) {
                        logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
                    }
                }
                // 1.2. 判断对应bean是否为配置类,如果是,则加入到configCandidates
                else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
                    configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
                }
            }
    
            // Return immediately if no @Configuration classes were found
            // 1.3 如果不存在配置类,则直接return
            if (configCandidates.isEmpty()) {
                return;
            }
    
            // Sort by previously determined @Order value, if applicable
            // 2. 对configCandidates 进行 排序,按照@Order 配置的值进行排序
            Collections.sort(configCandidates, new Comparator() {
                @Override
                public int compare(BeanDefinitionHolder bd1, BeanDefinitionHolder bd2) {
                    int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
                    int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
                    return (i1 < i2) ? -1 : (i1 > i2) ? 1 : 0;
                }
            });
    
            // Detect any custom bean name generation strategy supplied through the enclosing application context
            // 3. 如果BeanDefinitionRegistry 是SingletonBeanRegistry 子类的话,由于我们当前传入的是DefaultListableBeanFactory,是
            // SingletonBeanRegistry 的子类。因此会将registry强转为SingletonBeanRegistry
            SingletonBeanRegistry sbr = null;
            if (registry instanceof SingletonBeanRegistry) {
                sbr = (SingletonBeanRegistry) registry;
                if (!this.localBeanNameGeneratorSet && sbr.containsSingleton(CONFIGURATION_BEAN_NAME_GENERATOR)) {
                    // 如果localBeanNameGeneratorSet 等于false 并且SingletonBeanRegistry 中有 id 为 org.springframework.context.annotation.internalConfigurationBeanNameGenerator
                    // 的bean .则将componentScanBeanNameGenerator,importBeanNameGenerator 赋值为 该bean.
                    BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
                    this.componentScanBeanNameGenerator = generator;
                    this.importBeanNameGenerator = generator;
                }
            }
    
            // Parse each @Configuration class
            // 4. 实例化ConfigurationClassParser 为了解析 各个配置类
            ConfigurationClassParser parser = new ConfigurationClassParser(
                    this.metadataReaderFactory, this.problemReporter, this.environment,
                    this.resourceLoader, this.componentScanBeanNameGenerator, registry);
    
            // 实例化2个set,candidates 用于将之前加入的configCandidates 进行去重
            // alreadyParsed 用于判断是否处理过
            Set candidates = new LinkedHashSet(configCandidates);
            Set alreadyParsed = new HashSet(configCandidates.size());
            // 5. 进行解析
            do {
                parser.parse(candidates);
                parser.validate();
    
                Set configClasses = new LinkedHashSet(parser.getConfigurationClasses());
                configClasses.removeAll(alreadyParsed);
    
                // Read the model and create bean definitions based on its content
                if (this.reader == null) {
                    this.reader = new ConfigurationClassBeanDefinitionReader(
                            registry, this.sourceExtractor, this.resourceLoader, this.environment,
                            this.importBeanNameGenerator, parser.getImportRegistry());
                }
                this.reader.loadBeanDefinitions(configClasses);
                alreadyParsed.addAll(configClasses);
    
                candidates.clear();
                if (registry.getBeanDefinitionCount() > candidateNames.length) {
                    String[] newCandidateNames = registry.getBeanDefinitionNames();
                    Set oldCandidateNames = new HashSet(Arrays.asList(candidateNames));
                    Set 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
            // 6. 
            if (sbr != null) {
                if (!sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
                    // 如果SingletonBeanRegistry 不包含org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry
                    // 则注册一个,bean 为 ImportRegistry. 一般都会进行注册的
                    sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
                }
            }
    
            // 7. 清除缓存
            if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
                ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
            }
        }

    7件事:

    1. 获取已经注册的bean名称,进行遍历

      1. 如果BeanDefinition 中的configurationClass 属性为full 或者lite ,则意味着已经处理过了,直接跳过
      2. 判断对应bean是否为配置类,如果是,则加入到configCandidates.
      3. 如果不存在配置类,则直接return
    2. 对configCandidates 进行 排序,按照@Order 配置的值进行排序
    3. 如果BeanDefinitionRegistry 是SingletonBeanRegistry 子类的话,由于我们当前传入的是DefaultListableBeanFactory,是 SingletonBeanRegistry 的子类。因此会将registry强转为SingletonBeanRegistry.

      • 如果localBeanNameGeneratorSet 等于false 并且SingletonBeanRegistry 中有 id 为 org.springframework.context.annotation.internalConfigurationBeanNameGenerator的bean .则将componentScanBeanNameGenerator,importBeanNameGenerator 赋值为 该bean.
    4. 实例化ConfigurationClassParser 为了解析各个配置类.实例化2个set,candidates 用于将之前加入的configCandidates 进行去重,alreadyParsed 用于判断是否处理过
    5. 进行解析

      1. 调用ConfigurationClassParser#parse进行解析
      2. 将解析过的配置类加入到configClasses,并将configClasses去重已经处理过的,以防止重复加载
      3. 如果reader为null,则实例化ConfigurationClassBeanDefinitionReader
      4. 调用ConfigurationClassBeanDefinitionReader#loadBeanDefinitions 进行加载,并加入到alreadyParsed中,用于去重
      5. 将candidates进行清空,如果registry中注册的bean的数量 大于 之前获得的数量,则意味着在解析过程中又新加入了很多,那么就需要对其进行解析
    6. 如果SingletonBeanRegistry 不包含org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry,则注册一个,bean 为 ImportRegistry. 一般都会进行注册的
    7. 清除缓存

    1.2 判断对应bean是否为配置类 调用的是ConfigurationClassUtils#checkConfigurationClassCandidate.代码如下:

        public static boolean checkConfigurationClassCandidate(BeanDefinition beanDef, MetadataReaderFactory metadataReaderFactory) {
            // 1. 获取类名,如果类名不存在则返回false
            String className = beanDef.getBeanClassName();
            if (className == null) {
                return false;
            }
    
            // 2. 获得AnnotationMetadata
            AnnotationMetadata metadata;
            if (beanDef instanceof AnnotatedBeanDefinition &&
                    className.equals(((AnnotatedBeanDefinition) beanDef).getMetadata().getClassName())) {
                // Can reuse the pre-parsed metadata from the given BeanDefinition...
                // 2.1 如果BeanDefinition 是 AnnotatedBeanDefinition的实例,并且className 和 BeanDefinition中 的元数据 的类名相同
                // 则直接从BeanDefinition 获得Metadata
                metadata = ((AnnotatedBeanDefinition) beanDef).getMetadata();
            }
            else if (beanDef instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) beanDef).hasBeanClass()) {
                // Check already loaded Class if present...
                // since we possibly can't even load the class file for this Class.
                // 2.2 如果BeanDefinition 是 AnnotatedBeanDefinition的实例,并且beanDef 有 beanClass 属性存在
                // 则实例化StandardAnnotationMetadata
                Class beanClass = ((AbstractBeanDefinition) beanDef).getBeanClass();
                metadata = new StandardAnnotationMetadata(beanClass, true);
            }
            else {
                try {
                    // 2.3 否则 通过MetadataReaderFactory 中的MetadataReader 进行读取
                    MetadataReader metadataReader = metadataReaderFactory.getMetadataReader(className);
                    metadata = metadataReader.getAnnotationMetadata();
                }
                catch (IOException ex) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Could not find class file for introspecting configuration annotations: " + className, ex);
                    }
                    return false;
                }
            }
    
            // 3. 
            if (isFullConfigurationCandidate(metadata)) {
                // 3.1 如果存在Configuration 注解,则为BeanDefinition 设置configurationClass属性为full
                beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL);
            }
            else if (isLiteConfigurationCandidate(metadata)) {
                // 3.2 如果AnnotationMetadata 中有Component,ComponentScan,Import,ImportResource 注解中的任意一个,或者存在 被@bean 注解的方法,则返回true.
                // 则设置configurationClass属性为lite
                beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE);
            }
            else {
                // 3.3 返回false
                return false;
            }
    
            // It's a full or lite configuration candidate... Let's determine the order value, if any.
            // 4. 如果该类被@Order所注解,则设置order属性为@Order的值
            Map orderAttributes = metadata.getAnnotationAttributes(Order.class.getName());
            if (orderAttributes != null) {
                beanDef.setAttribute(ORDER_ATTRIBUTE, orderAttributes.get(AnnotationUtils.VALUE));
            }
    
            return true;
        }

    5件事:

    1. 获取类名,如果类名不存在则返回false
    2. 获得AnnotationMetadata

      1. 如果BeanDefinition 是 AnnotatedBeanDefinition的实例,并且className 和 BeanDefinition中的元数据的类名相同,则直接从BeanDefinition 获得Metadata
      2. 如果BeanDefinition 是 AnnotatedBeanDefinition的实例,并且beanDef 有 beanClass属性存在,则实例化StandardAnnotationMetadata
      3. 否则 通过MetadataReaderFactory 中的MetadataReader 进行读取
    3. 进行判断

      1. 如果存在Configuration 注解,则为BeanDefinition 设置configurationClass属性为full.
      2. 如果AnnotationMetadata 中有Component,ComponentScan,Import,ImportResource 注解中的任意一个,或者存在 被@bean 注解的方法,则返回true.
      3. 否则,返回false
    4. 如果该类被@Order所注解,则设置order属性为@Order的值
    5. 返回true.

    5.1 调用的是ConfigurationClassParser#parse,代码如下:

        public void parse(Set configCandidates) {
            this.deferredImportSelectors = new LinkedList();
    
                    for (BeanDefinitionHolder holder : configCandidates) {
                BeanDefinition bd = holder.getBeanDefinition();
                try {
                    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();
        }

    3件事

    1. 实例化deferredImportSelectors
    2. 遍历configCandidates ,进行处理.根据BeanDefinition 的类型 做不同的处理,一般都会调用ConfigurationClassParser#parse 进行解析
    3. 处理ImportSelect

    其中第2步 执行的代码如下:

            protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
            processConfigurationClass(new ConfigurationClass(metadata, beanName));
        }

    最终调用

        protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
            // 1. 判断是否应该被跳过
            if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
                return;
            }
    
            // 2. 处理Imported 的情况
            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 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);
            do {
                // 3. 递归调用进行解析
                sourceClass = doProcessConfigurationClass(configClass, sourceClass);
            }
            while (sourceClass != null);
    
            // 4. 添加到configurationClasses中
            this.configurationClasses.put(configClass, configClass);
        }

    4件事:

    1. 判断是否应该被跳过.通过调用ConditionEvaluator#shouldSkip实现的,代码如下:

          public boolean shouldSkip(AnnotatedTypeMetadata metadata, ConfigurationPhase phase) {
          // 1. 如果这个类没有被@Conditional注解所修饰,不会skip
          if (metadata == null || !metadata.isAnnotated(Conditional.class.getName())) {
              return false;
          }
      
          // 2. 如果参数中沒有设置条件注解的生效阶段
          if (phase == null) {
              // 是配置类的话直接使用PARSE_CONFIGURATION阶段
              if (metadata instanceof AnnotationMetadata &&
                      ConfigurationClassUtils.isConfigurationCandidate((AnnotationMetadata) metadata)) {
                  return shouldSkip(metadata, ConfigurationPhase.PARSE_CONFIGURATION);
              }
              // 否则使用REGISTER_BEAN阶段
              return shouldSkip(metadata, ConfigurationPhase.REGISTER_BEAN);
          }
      
          List conditions = new ArrayList(); // 要解析的配置类的条件集合
          // 3. 获取配置类的条件注解得到条件数据,并添加到集合中
          for (String[] conditionClasses : getConditionClasses(metadata)) {
              for (String conditionClass : conditionClasses) {
                  Condition condition = getCondition(conditionClass, this.context.getClassLoader());
                  conditions.add(condition);
              }
          }
      
          AnnotationAwareOrderComparator.sort(conditions);
      
          // 4. 遍历conditions,进行判断
          for (Condition condition : conditions) {
              ConfigurationPhase requiredPhase = null;
              if (condition instanceof ConfigurationCondition) {
                  requiredPhase = ((ConfigurationCondition) condition).getConfigurationPhase();
              }
              if (requiredPhase == null || requiredPhase == phase) {
                  // 阶段不满足条件的话,返回true并跳过这个bean的解析
                  if (!condition.matches(this.context, metadata)) {
                      return true;
                  }
              }
          }
      
          return false;
          }
      

      4件事

      1. 如果这个类没有被@Conditional注解所修饰,不会skip,返回false
      2. 如果参数中沒有设置条件注解的生效阶段

        1. 是配置类的话直接使用PARSE_CONFIGURATION阶段,递归调用shouldSkip 进行判断
        2. 否则使用REGISTER_BEAN阶段,递归调用shouldSkip 进行判断
      3. 获取配置类的条件注解得到条件数据,并添加到集合中
      4. 遍历conditions,进行判断,如果阶段不满足条件的话,返回true并跳过这个bean的解析
    2. 处理Imported 的情况
    3. 递归调用进行解析
    4. 添加到configurationClasses中

    其中第三步,代码如下:

        protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
                throws IOException {
    
            // 1. Recursively process any member (nested) classes first 处理内部类
            processMemberClasses(configClass, sourceClass);
    
            // 2. Process any @PropertySource annotations  处理@PropertySource
            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");
                }
            }
    
            // 3. Process any @ComponentScan annotations 处理@ComponentScan
            Set 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
                    // 3.1 进行扫描
                    Set scannedBeanDefinitions =
                            this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
                    // Check the set of scanned definitions for any further config classes and parse recursively if needed
                    // 3.2 依次遍历扫描的配置类进行解析
                    for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
                        if (ConfigurationClassUtils.checkConfigurationClassCandidate(
                                holder.getBeanDefinition(), this.metadataReaderFactory)) {
                            parse(holder.getBeanDefinition().getBeanClassName(), holder.getBeanName());
                        }
                    }
                }
            }
    
            // 4. Process any @Import annotations 处理@Import
            processImports(configClass, sourceClass, getImports(sourceClass), true);
    
            // 5. Process any @ImportResource annotations
            if (sourceClass.getMetadata().isAnnotated(ImportResource.class.getName())) {
                AnnotationAttributes importResource =
                        AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
                String[] resources = importResource.getStringArray("locations");
                // 遍历配置的locations,加入到configClass 中的ImportedResource
                Class readerClass = importResource.getClass("reader");
                for (String resource : resources) {
                    String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
                    configClass.addImportedResource(resolvedResource, readerClass);
                }
            }
    
            // 6. Process individual @Bean methods
            Set beanMethods = retrieveBeanMethodMetadata(sourceClass);
            // 遍历@Bean注释的方法,添加到configClass
            for (MethodMetadata methodMetadata : beanMethods) {
                configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
            }
    
            // 7. Process default methods on interfaces
            processInterfaces(configClass, sourceClass);
    
            // 8. Process superclass, if any 如果有父类的话,则返回父类进行进一步的解析
            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;
        }
    

    8件事

    1. 处理内部类.代码如下:

          private void processMemberClasses(ConfigurationClass configClass, SourceClass sourceClass) throws IOException {
          // 1. 遍历class中的内部类
          for (SourceClass memberClass : sourceClass.getMemberClasses()) {
              if (ConfigurationClassUtils.isConfigurationCandidate(memberClass.getMetadata()) &&
                      !memberClass.getMetadata().getClassName().equals(configClass.getMetadata().getClassName())) {
                  // 2. 如果该内部类是一个配置类,并且该内部类的类名和configClass的类名不相同
                  if (this.importStack.contains(configClass)) {
                      // 2.1 如果importStack 包含该configClass的化,则意味发生了循环依赖,则会抛出BeanDefinitionParsingException 异常
                      this.problemReporter.error(new CircularImportProblem(configClass, this.importStack));
                  }
                  else {
                      // 2.2 否则加入到importStack,调用processConfigurationClass 进行解析
                      this.importStack.push(configClass);
                      try {
                          processConfigurationClass(memberClass.asConfigClass(configClass));
                      }
                      finally {
                          this.importStack.pop();
                      }
                  }
              }
          }
          }

      2件事:

      1. 遍历class中的内部类
      2. 如果该内部类是一个配置类,并且该内部类的类名和configClass的类名不相同

        1. 如果importStack 包含该configClass的化,则意味发生了循环依赖,则会抛出BeanDefinitionParsingException 异常
        2. 否则加入到importStack,调用processConfigurationClass 进行解析,最后在弹出该configClass.
    2. 处理@PropertySource.通过遍历该类中的@PropertySource的注解,如果该类中的environment是ConfigurableEnvironment 子类的话,则调用processPropertySource进行处理.否则打印警告日志.一般都是ConfigurableEnvironment的子类.代码如下:

          private void processPropertySource(AnnotationAttributes propertySource) throws IOException { // 1. 解析name、encoding值 String name = propertySource.getString("name"); if (!StringUtils.hasLength(name)) { name = null; } String encoding = propertySource.getString("encoding"); if (!StringUtils.hasLength(encoding)) { encoding = null; } // 2. 解析value(数组)以及ignoreResourceNotFound值 String[] locations = propertySource.getStringArray("value"); Assert.isTrue(locations.length > 0, "At least one @PropertySource(value) location is required"); boolean ignoreResourceNotFound = propertySource.getBoolean("ignoreResourceNotFound"); // 3. 解析factory,如果该值没有配置,默认为PropertySourceFactory则直接实例化DefaultPropertySourceFactory类,否则开始实例化自定义的类 Class factoryClass = propertySource.getClass("factory"); PropertySourceFactory factory = (factoryClass == PropertySourceFactory.class ? DEFAULT_PROPERTY_SOURCE_FACTORY : BeanUtils.instantiateClass(factoryClass)); for (String location : locations) { try { // 4.1 对location进行SPEL表达式的解析。比如当前的配置环境中有一个属性为app=shareniu,我们配置的location为${app}最终值为shareniu。通过这里的处理逻辑可以知道location支持多环境的切换以及表达式的配置 String resolvedLocation = this.environment.resolveRequiredPlaceholders(location); // 4.2 使用资源加载器resourceLoader将resolvedLocation抽象为Resource Resource resource = this.resourceLoader.getResource(resolvedLocation); // 4.3 调用addPropertySource属性进行处理。将指定的资源处理之后,添加到当前springboot运行的环境中 addPropertySource(factory.createPropertySource(name, new EncodedResource(resource, encoding))); } catch (IllegalArgumentException ex) { // 5. 如果上述的任意步骤报错,则开始查找ignoreResourceNotFound的值,如果该值为treu,则忽略异常,否则直接报错 // Placeholders not resolvable if (ignoreResourceNotFound) { if (logger.isInfoEnabled()) { logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage()); } } else { throw ex; } } catch (IOException ex) { // Resource not found when trying to open it if (ignoreResourceNotFound && (ex instanceof FileNotFoundException || ex instanceof UnknownHostException)) { if (logger.isInfoEnabled()) { logger.info("Properties location [" + location + "] not resolvable: " + ex.getMessage()); } } else { throw ex; } } } }

      5件事:

      1. 解析name、encoding值
      2. 解析value(数组)以及ignoreResourceNotFound值
      3. 解析factory,如果该值没有配置,默认为PropertySourceFactory则直接实例化DefaultPropertySourceFactory类,否则开始实例化自定义的类
      4. 遍历配置的locations进行处理

        1. 对location进行SPEL表达式的解析。比如当前的配置环境中有一个属性为app=shareniu,我们配置的location为${app}最终值为shareniu。通过这里的处理逻辑可以知道location支持多环境的切换以及表达式的配置
        2. 使用资源加载器resourceLoader将resolvedLocation抽象为Resource
        3. 调用addPropertySource属性进行处理。将指定的资源处理之后,添加到当前springboot运行的环境中

      5.如果上述的任意步骤报错,则开始查找ignoreResourceNotFound的值,如果该值为treu,则忽略异常,否则直接报错

    3. 处理@ComponentScan,通过遍历该类上的@ComponentScan 注解,并且通过ConditionEvaluator#shouldSkip判断后

      1. 依次通过ComponentScanAnnotationParser#parse进行扫描。最终调用ClassPathBeanDefinitionScanner#doScan.代码如下:

            protected Set doScan(String... basePackages) {
            Assert.notEmpty(basePackages, "At least one base package must be specified");
            Set beanDefinitions = new LinkedHashSet();
            for (String basePackage : basePackages) {
            // 扫描basePackage路径下的java文件
            Set candidates = findCandidateComponents(basePackage);
            for (BeanDefinition candidate : candidates) {
                // 解析scope属性
                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) {
                    // 如果是AnnotatedBeanDefinition类型,则检查常用注解:如lazy等
                    AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
                }
                // 检查当前bean是否已经注册
                if (checkCandidate(beanName, candidate)) {
                    BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
                    // 如果当前bean是用于生成代理的bean那么需要进一步处理
                    definitionHolder =
                            AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
                    beanDefinitions.add(definitionHolder);
                    registerBeanDefinition(definitionHolder, this.registry);
                }
            }
            }
            return beanDefinitions;
            }
        
        1. 遍历basePackages,通过findCandidateComponents方法扫描basePackage路径下的java文件
        2. 如果扫描到文件的话,则遍历之.

          1. 解析scope属性
          2. 生成beanName.
          3. 如果该 BeanDefinition 是AbstractBeanDefinition 的子类的话,则调用postProcessBeanDefinition为其设置默认值.代码如下:

                    protected void postProcessBeanDefinition(AbstractBeanDefinition beanDefinition, String beanName) {
                beanDefinition.applyDefaults(this.beanDefinitionDefaults);
                if (this.autowireCandidatePatterns != null) {
                beanDefinition.setAutowireCandidate(PatternMatchUtils.simpleMatch(this.autowireCandidatePatterns, beanName));
                }
                }
            1. 为其设置默认值.

                      public void applyDefaults(BeanDefinitionDefaults defaults) {
                  setLazyInit(defaults.isLazyInit());//false
                  setAutowireMode(defaults.getAutowireMode());//AUTOWIRE_NO
                  setDependencyCheck(defaults.getDependencyCheck());//DEPENDENCY_CHECK_NONE
                  setInitMethodName(defaults.getInitMethodName());// null
                  setEnforceInitMethod(false);
                  setDestroyMethodName(defaults.getDestroyMethodName());//null
                  setEnforceDestroyMethod(false);
                  }
            2. 如果autowireCandidatePatterns 不等于null的话,则设置AutowireCandidate.
          4. 如果该BeanDefinition是AnnotatedBeanDefinition的子类,则调用AnnotationConfigUtils#processCommonDefinitionAnnotations,检查常用注解:如lazy等
          5. 检查当前bean是否已经注册,如果没有注册的话,则

            1. 生成BeanDefinitionHolder
            2. 如果当前bean是用于生成代理的bean那么需要进一步处理,代码如下:

                      static BeanDefinitionHolder applyScopedProxyMode(
                  ScopeMetadata metadata, BeanDefinitionHolder definition, BeanDefinitionRegistry registry) {
                  ScopedProxyMode scopedProxyMode = metadata.getScopedProxyMode();
                  if (scopedProxyMode.equals(ScopedProxyMode.NO)) {
                  return definition;
                  }
                  boolean proxyTargetClass = scopedProxyMode.equals(ScopedProxyMode.TARGET_CLASS);
                  return ScopedProxyCreator.createScopedProxy(definition, registry, proxyTargetClass);
                  }

              由于一般ScopedProxyMode都是NO,因此也就不会生成代理

            3. 添加到beanDefinitions中
            4. 向BeanDefinitionRegistry进行注册
      2. 依次遍历扫描的配置类进行递归解析.最终又会调用ConfigurationClassParser#processConfigurationClass
    4. 处理@Import.代码如下:

              private void processImports(ConfigurationClass configClass, SourceClass currentSourceClass,
              Collection importCandidates, boolean checkForCircularImports) throws IOException {
      
          // 1. 如果importCandidates为空,则直接return
          if (importCandidates.isEmpty()) {
              return;
          }
      
          // 2. 进行循环依赖的检查
          if (checkForCircularImports && isChainedImportOnStack(configClass)) {
              this.problemReporter.error(new CircularImportProblem(configClass, this.importStack));
          }
          else {
              this.importStack.push(configClass);
              try {
                  // 3. 如果不存在循环依赖,则依次遍历处理之
                  for (SourceClass candidate : importCandidates) {
                      if (candidate.isAssignable(ImportSelector.class)) {
                          // 3.1 如果是ImportSelector的子类
                          // Candidate class is an ImportSelector -> delegate to it to determine imports
                          Class candidateClass = candidate.loadClass();
                          // 则实例化后,调用ParserStrategyUtils#invokeAwareMethods
                          ImportSelector selector = BeanUtils.instantiateClass(candidateClass, ImportSelector.class);
                          ParserStrategyUtils.invokeAwareMethods(
                                  selector, this.environment, this.resourceLoader, this.registry);
                          if (this.deferredImportSelectors != null && selector instanceof DeferredImportSelector) {
                              // 3.2 如果当前类是DeferredImportSelector 的实现,则加入到deferredImportSelectors
                              this.deferredImportSelectors.add(
                                      new DeferredImportSelectorHolder(configClass, (DeferredImportSelector) selector));
                          }
                          else {
                              // 3.3 如果不是,则调用processImports 进行处理.
                              String[] importClassNames = selector.selectImports(currentSourceClass.getMetadata());
                              Collection importSourceClasses = asSourceClasses(importClassNames);
                              processImports(configClass, currentSourceClass, importSourceClasses, false);
                          }
                      }
                      else if (candidate.isAssignable(ImportBeanDefinitionRegistrar.class)) {
                          // Candidate class is an ImportBeanDefinitionRegistrar ->
                          // delegate to it to register additional bean definitions
                          // 如果是ImportBeanDefinitionRegistrar的子类,则实例化后,调用ParserStrategyUtils#invokeAwareMethods,
                          // 添加到configClass中
                          Class candidateClass = candidate.loadClass();
                          ImportBeanDefinitionRegistrar registrar =
                                  BeanUtils.instantiateClass(candidateClass, ImportBeanDefinitionRegistrar.class);
                          ParserStrategyUtils.invokeAwareMethods(
                                  registrar, this.environment, this.resourceLoader, this.registry);
                          configClass.addImportBeanDefinitionRegistrar(registrar, currentSourceClass.getMetadata());
                      }
                      else {
                          // Candidate class not an ImportSelector or ImportBeanDefinitionRegistrar ->
                          // process it as an @Configuration class
                          // 3. 否则,加入到importStack后调用processConfigurationClass 进行处理.
                          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();
              }
          }
          }
      1. 如果@Import注解不存在的话,则直接return.
      2. 进行循环依赖的检查,如果存在循环依赖的话,则直接抛出异常
      3. 加入importStack中,用于循环依赖的检查,依次遍历 @Import

        1. 如果是ImportSelector的子类,则实例化后,调用ParserStrategyUtils#invokeAwareMethods.

          1. 如果当前类是DeferredImportSelector 的实现,则加入到deferredImportSelectors
          2. 如果不是,则调用processImports 进行处理.
        2. 如果是ImportBeanDefinitionRegistrar的子类,则实例化后,调用ParserStrategyUtils#invokeAwareMethods,添加到configClass中
        3. 否则,加入到importStack后调用processConfigurationClass 进行处理.
      4. 最后,从importStack栈顶元素.

      其中ParserStrategyUtils#invokeAwareMethods,代码如下:

              public static void invokeAwareMethods(Object parserStrategyBean, Environment environment,
              ResourceLoader resourceLoader, BeanDefinitionRegistry registry) {
      
          if (parserStrategyBean instanceof Aware) {
              if (parserStrategyBean instanceof BeanClassLoaderAware) {
                  ClassLoader classLoader = (registry instanceof ConfigurableBeanFactory ?
                          ((ConfigurableBeanFactory) registry).getBeanClassLoader() : resourceLoader.getClassLoader());
                  ((BeanClassLoaderAware) parserStrategyBean).setBeanClassLoader(classLoader);
              }
              if (parserStrategyBean instanceof BeanFactoryAware && registry instanceof BeanFactory) {
                  ((BeanFactoryAware) parserStrategyBean).setBeanFactory((BeanFactory) registry);
              }
              if (parserStrategyBean instanceof EnvironmentAware) {
                  ((EnvironmentAware) parserStrategyBean).setEnvironment(environment);
              }
              if (parserStrategyBean instanceof ResourceLoaderAware) {
                  ((ResourceLoaderAware) parserStrategyBean).setResourceLoader(resourceLoader);
              }
          }
          }
      1. 如果parserStrategyBean 是Aware 的子类

        1. 如果parserStrategyBean是BeanClassLoaderAware的子类,则为其注入ClassLoader
        2. 如果parserStrategyBean是BeanFactoryAware的子类并且registry是BeanFactory的子类,则为其注入BeanFactory
        3. 如果parserStrategyBean是EnvironmentAware的子类,则为其注入Environment
        4. 如果parserStrategyBean是ResourceLoaderAware的子类,则为其注入ResourceLoader
      2. 否则不进行处理.
    5. 处理@ImportResource,通过获得其@ImportResource,获得locations值后, 遍历配置的locations,加入到configClass 中的ImportedResource.
    6. 处理被@Bean注解的方法,遍历@Bean注释的方法,添加到configClass中的BeanMethod
    7. 处理接口中被@Bean注解默认方法,代码如下:

          private void processInterfaces(ConfigurationClass configClass, SourceClass sourceClass) throws IOException {
          // 1. 遍历sourceClass 的接口
          for (SourceClass ifc : sourceClass.getInterfaces()) {
              // 2. 获得被@bean注释的方法
              Set beanMethods = retrieveBeanMethodMetadata(ifc);
              for (MethodMetadata methodMetadata : beanMethods) {
                  if (!methodMetadata.isAbstract()) {
                      // A default method or other concrete method on a Java 8+ interface...
                      // 3. 如果不是抽象方法的话,则加入到configClass的BeanMethod
                      configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
                  }
              }
              // 4. 递归处理
              processInterfaces(configClass, ifc);
          }
          }
      1. 遍历sourceClass 的接口
      2. 获得被@bean注释的方法
      3. 如果不是抽象方法的话,则加入到configClass的BeanMethod
      4. 递归调用processInterfaces,看其父接口中是否存在被@bean注解的方法,直到父接口不存在.
    8. 如果有父类的话,则返回父类进行进一步的解析,否则返回null

    5.4 调用的是ConfigurationClassBeanDefinitionReader#loadBeanDefinitions,代码如下:

            public void loadBeanDefinitions(Set configurationModel) {
            // 1. 实例化TrackedConditionEvaluator
            TrackedConditionEvaluator trackedConditionEvaluator = new TrackedConditionEvaluator();
            // 2. 遍历configurationModel,依次调用loadBeanDefinitionsForConfigurationClass
            for (ConfigurationClass configClass : configurationModel) {
                loadBeanDefinitionsForConfigurationClass(configClass, trackedConditionEvaluator);
            }
        }

    2件事:

    1. 实例化TrackedConditionEvaluator
    2. 遍历configurationModel,依次调用loadBeanDefinitionsForConfigurationClass进行加载.代码如下:

          private void loadBeanDefinitionsForConfigurationClass(ConfigurationClass configClass,
              TrackedConditionEvaluator trackedConditionEvaluator) {
      
          // 1. 使用条件注解判断是否需要跳过这个配置类
          if (trackedConditionEvaluator.shouldSkip(configClass)) {
              String beanName = configClass.getBeanName();
              // 1.1 跳过配置类的话在Spring容器中移除bean的注册
              if (StringUtils.hasLength(beanName) && this.registry.containsBeanDefinition(beanName)) {
                  this.registry.removeBeanDefinition(beanName);
              }
              // 1.2 从importRegistry 进行删除.
              this.importRegistry.removeImportingClass(configClass.getMetadata().getClassName());
              return;
          }
      
          if (configClass.isImported()) {
              // 2. 如果自身是被@Import注释所import的,注册自己
              registerBeanDefinitionForImportedConfigurationClass(configClass);
          }
          // 3. 遍历BeanMethods,依次对其进行注册.
          for (BeanMethod beanMethod : configClass.getBeanMethods()) {
              loadBeanDefinitionsForBeanMethod(beanMethod);
          }
          // 4.注册@ImportResource注解注释的资源文件中的bean
          loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
          // 5. 注册@Import注解中的ImportBeanDefinitionRegistrar接口的registerBeanDefinitions
          loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
          }

      5件事:

      1. 使用条件注解判断是否需要跳过这个配置类,如果需要跳过的话,则Spring容器中移除该bean.并且从importRegistry删除.然后直接return.否则执行第2步.
      2. 如果自身是被@Import注解所import的,则调用registerBeanDefinitionForImportedConfigurationClass进行注册.代码如下:

            private void registerBeanDefinitionForImportedConfigurationClass(ConfigurationClass configClass) {
            // 1. 根据configClass中配置的AnnotationMetadata 实例化AnnotatedGenericBeanDefinition
            AnnotationMetadata metadata = configClass.getMetadata();
            AnnotatedGenericBeanDefinition configBeanDef = new AnnotatedGenericBeanDefinition(metadata);
            // 2 进行属性的设置
            // 2.1 解析该configClass的Scope
            ScopeMetadata scopeMetadata = scopeMetadataResolver.resolveScopeMetadata(configBeanDef);
            configBeanDef.setScope(scopeMetadata.getScopeName());
            // 2.2 生成bean的id
            String configBeanName = this.importBeanNameGenerator.generateBeanName(configBeanDef, this.registry);
            // 2.3 设置bean的一些属性,如LazyInit,Primary等
            AnnotationConfigUtils.processCommonDefinitionAnnotations(configBeanDef, metadata);
            // 3. 生成BeanDefinitionHolder,并对其尝试进行代理,最后向registry进行注册
            BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(configBeanDef, configBeanName);
            definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
            this.registry.registerBeanDefinition(definitionHolder.getBeanName(), definitionHolder.getBeanDefinition());
            configClass.setBeanName(configBeanName);
            if (logger.isDebugEnabled()) {
            logger.debug("Registered bean definition for imported class '" + configBeanName + "'");
            }
            }

        3件事

        1. 根据configClass中配置的AnnotationMetadata 实例化AnnotatedGenericBeanDefinition
        2. 进行属性的设置

          1. 解析该configClass的Scope
          2. 生成bean的id
          3. 设置bean的一些属性,如LazyInit,Primary等
          4. 生成BeanDefinitionHolder,并对其尝试进行代理,最后向registry进行注册
      3. 遍历BeanMethods,依次对其调用loadBeanDefinitionsForBeanMethod进行注册.代码如下:

            private void loadBeanDefinitionsForBeanMethod(BeanMethod beanMethod) {
            // 1. 获得声明该BeanMethod的ConfigurationClass
            ConfigurationClass configClass = beanMethod.getConfigurationClass();
            // 获得BeanMethod的MethodMetadata和methodName
            MethodMetadata metadata = beanMethod.getMetadata();
            String methodName = metadata.getMethodName();
            // Do we need to mark the bean as skipped by its condition?
            // 2. 进行判断,是否应该跳过处理
            // 2.1 如果ConditionEvaluator#shouldSkip返回true,则添加到configClass的skippedBeanMethods中,return
            if (this.conditionEvaluator.shouldSkip(metadata, ConfigurationPhase.REGISTER_BEAN)) {
            configClass.skippedBeanMethods.add(methodName);
            return;
            }
            // 2.2 如果configClass的skippedBeanMethods包含该methodName的话,不进行处理,
            if (configClass.skippedBeanMethods.contains(methodName)) {
            return;
            }
            // Consider name and any aliases
            // 3. 从@Bean 中获得配置的names,如果names不为空的话,则第一个为bean的id,否则该方法名字作为bean的id
            AnnotationAttributes bean = AnnotationConfigUtils.attributesFor(metadata, Bean.class);
            List names = new ArrayList(Arrays.asList(bean.getStringArray("name")));
            String beanName = (!names.isEmpty() ? names.remove(0) : methodName);
            // Register aliases even when overridden
            // 4. 将names 当做别名进行注册
            for (String alias : names) {
            this.registry.registerAlias(beanName, alias);
            }
            // Has this effectively been overridden before (e.g. via XML)?
            // 5. 如果存在重复定义的情况,则直接return
            if (isOverriddenByExistingDefinition(beanMethod, beanName)) {
            return;
            }
            // 6. 实例化ConfigurationClassBeanDefinition
            ConfigurationClassBeanDefinition beanDef = new ConfigurationClassBeanDefinition(configClass, metadata);
            beanDef.setResource(configClass.getResource());
            beanDef.setSource(this.sourceExtractor.extractSource(metadata, configClass.getResource()));
            if (metadata.isStatic()) {
            // 6.1  如果该方法是静态的,则将methodName设置为工厂方法
            // static @Bean method
            beanDef.setBeanClassName(configClass.getMetadata().getClassName());
            beanDef.setFactoryMethodName(methodName);
            }
            else {
            // instance @Bean method
            // 6.2 如果是实例方法的话,则将configClass的BeanName设置为FactoryBeanName,methodName设置为UniqueFactoryMethodName
            beanDef.setFactoryBeanName(configClass.getBeanName());
            beanDef.setUniqueFactoryMethodName(methodName);
            }
            // 6.3 设置AutowireMode 为 构造器注入
            beanDef.setAutowireMode(RootBeanDefinition.AUTOWIRE_CONSTRUCTOR);
            // 设置skipRequiredCheck属性为true.
            beanDef.setAttribute(RequiredAnnotationBeanPostProcessor.SKIP_REQUIRED_CHECK_ATTRIBUTE, Boolean.TRUE);
            // 6.4 进行一些常用的属性设置
            AnnotationConfigUtils.processCommonDefinitionAnnotations(beanDef, metadata);
            Autowire autowire = bean.getEnum("autowire");
            if (autowire.isAutowire()) {
            beanDef.setAutowireMode(autowire.value());
            }
            String initMethodName = bean.getString("initMethod");
            if (StringUtils.hasText(initMethodName)) {
            // 设置 InitMethod
            beanDef.setInitMethodName(initMethodName);
            }
            String destroyMethodName = bean.getString("destroyMethod");
            if (destroyMethodName != null) {
            // 设置 DestroyMethod
            beanDef.setDestroyMethodName(destroyMethodName);
            }
            // Consider scoping
            // 6.5 设置ScopedProxyMode
            ScopedProxyMode proxyMode = ScopedProxyMode.NO;
            AnnotationAttributes attributes = AnnotationConfigUtils.attributesFor(metadata, Scope.class);
            if (attributes != null) {
            beanDef.setScope(attributes.getString("value"));
            proxyMode = attributes.getEnum("proxyMode");
            if (proxyMode == ScopedProxyMode.DEFAULT) {
                proxyMode = ScopedProxyMode.NO;
            }
            }
            // Replace the original bean definition with the target one, if necessary
            // 6.6 如果ScopedProxyMode 不等于NO,则生成代理
            BeanDefinition beanDefToRegister = beanDef;
            if (proxyMode != ScopedProxyMode.NO) {
            BeanDefinitionHolder proxyDef = ScopedProxyCreator.createScopedProxy(
                    new BeanDefinitionHolder(beanDef, beanName), this.registry,
                    proxyMode == ScopedProxyMode.TARGET_CLASS);
            beanDefToRegister = new ConfigurationClassBeanDefinition(
                    (RootBeanDefinition) proxyDef.getBeanDefinition(), configClass, metadata);
            }
            if (logger.isDebugEnabled()) {
            logger.debug(String.format("Registering bean definition for @Bean method %s.%s()",
                    configClass.getMetadata().getClassName(), beanName));
            }
            // 7. 进行注册
            this.registry.registerBeanDefinition(beanName, beanDefToRegister);
            }

        7件事:

        1. 获得声明该BeanMethod的ConfigurationClass,获得BeanMethod的MethodMetadata和methodName
        2. 进行判断,是否应该跳过处理

          1. 如果ConditionEvaluator#shouldSkip返回true,则添加到configClass的skippedBeanMethods中,return
          2. 如果configClass的skippedBeanMethods包含该methodName的话,不进行处理,
        3. 从@Bean 中获得配置的names,如果names不为空的话,则第一个为bean的id,否则该方法名字作为bean的id
        4. 将names 当做别名进行注册
        5. 如果存在重复定义的情况,则直接return
        6. 实例化ConfigurationClassBeanDefinition

          1. 如果该方法是静态的,则将methodName设置为工厂方法
          2. 否则如果是实例方法的话,则将configClass的BeanName设置为FactoryBeanName,methodName设置为UniqueFactoryMethodName
          3. 设置AutowireMode 为 构造器注入,设置skipRequiredCheck属性为true.
          4. 进行一些常用的属性设置
          5. 设置 InitMethod
          6. 设置 DestroyMethod
          7. 设置ScopedProxyMode,如果ScopedProxyMode 不等于NO,则生成代理
        7. 进行注册
      4. 注册@ImportResource注解注释的资源文件中的bean.代码如下:

            private void loadBeanDefinitionsFromImportedResources( Map> importedResources) { Map, BeanDefinitionReader> readerInstanceCache = new HashMap, BeanDefinitionReader>(); // 1. 遍历importedResources for (Map.Entry> entry : importedResources.entrySet()) { String resource = entry.getKey(); Class readerClass = entry.getValue(); // Default reader selection necessary? // 2. 选择BeanDefinitionReader if (BeanDefinitionReader.class == readerClass) { if (StringUtils.endsWithIgnoreCase(resource, ".groovy")) { // When clearly asking for Groovy, that's what they'll get... // 2.1 如果是.groovy,则为GroovyBeanDefinitionReader readerClass = GroovyBeanDefinitionReader.class; } else { // Primarily ".xml" files but for any other extension as well // 2.2 否则为XmlBeanDefinitionReader,一般都是XmlBeanDefinitionReader readerClass = XmlBeanDefinitionReader.class; } } // 3. 尝试从readerInstanceCache中获取对应的BeanDefinitionReader BeanDefinitionReader reader = readerInstanceCache.get(readerClass); if (reader == null) {// 如果不存在,则实例化一个 try { // Instantiate the specified BeanDefinitionReader reader = readerClass.getConstructor(BeanDefinitionRegistry.class).newInstance(this.registry); // Delegate the current ResourceLoader to it if possible if (reader instanceof AbstractBeanDefinitionReader) { // 如果reader是AbstractBeanDefinitionReader的子类的话,这个肯定是... AbstractBeanDefinitionReader abdr = ((AbstractBeanDefinitionReader) reader); abdr.setResourceLoader(this.resourceLoader); abdr.setEnvironment(this.environment); } // 然后放入readerInstanceCache,以防止重复实例化. readerInstanceCache.put(readerClass, reader); } catch (Throwable ex) { throw new IllegalStateException( "Could not instantiate BeanDefinitionReader class [" + readerClass.getName() + "]"); } } // TODO SPR-6310: qualify relative path locations as done in AbstractContextLoader.modifyLocations reader.loadBeanDefinitions(resource);}} 

        3件事:

        1. 遍历importedResources
        2. 选择BeanDefinitionReader

          1. 如果是.groovy结尾的话,则为GroovyBeanDefinitionReader
          2. 否则为XmlBeanDefinitionReader,一般都是XmlBeanDefinitionReader
        3. 尝试从readerInstanceCache中获取对应的BeanDefinitionReader,如果不存在,则实例化一个,然后放入到readerInstanceCache缓存中
        4. 调用BeanDefinitionReader#loadBeanDefinitions进行加载.

        由于一般情况下都是XmlBeanDefinitionReader,最终会调用XmlBeanDefinitionReader#loadBeanDefinitions进行加载,这部分属于spring加载xml部分了,碍于篇幅,这里就不在展开了,后续会有文章进行分析的.

      5. 注册@Import注解中的ImportBeanDefinitionRegistrar接口的registerBeanDefinitions.代码如下:

            private void loadBeanDefinitionsFromRegistrars(Map registrars) {
            for (Map.Entry entry : registrars.entrySet()) {
            entry.getKey().registerBeanDefinitions(entry.getValue(), this.registry);
            }
            }

        只是简单的进行注册.

    至此关于bean的加载我们就分析完了.

参考链接

spring boot实战(第十篇)Spring boot Bean加载源码分析


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