springboot2.x初探（五）

这一篇文章还是接着上一篇继续分析。

还是先上一张图：

我们继续看第十三步创建异常报告实例：

这个类就是一个报告SpringApplication启动过程中的错误的。具体的创建过程我们就不再细看，继续下一个步骤：

14.准备上下文：

代码中第一行和第二行是设置context的环境和资源加载器、类加载器、注册了一个单例的beannamegenerator，applyinitializers是将获取到的initializer中设置好context。对于listeners.contextPrepared方法：

发现这个listener中没有东西，其他的listener还不知道。

这个方法中设置了一系列的读取工具，并将主类加入了excludeFilter中。

下面看prepareContext方法中的最后一行：

这其中最主要的是context.addApplicationListener(listener);这句，将读取的listener添加到context中。到这里第十四步就看完了，这一步主要就是给context设置各种加载器和监听器，执行初始化器的初始化方法。

下面我们看refreshContext：

方法很简单，看来主要的内容都在refresh方法中了：

下面这段代码比较长我分了三段来截图：

我们一步一步来看：

看看具体方法：

根据注释我们知道这个方法主要就做了三件事事情：设置启动时间、设置激活标志、运行初始化为属性赋值。

我们看到这里的赋值交给了子类去实现。我们前面已经知道我们的context是：AnnotationConfigServletWebServerApplicationContext，我们在它的类中以及它的父类中查找这个 initPropertySources方法，最终在GenericWebApplicationContext中找到了这个方法：

这里经过debug发现什么都没有运行，因为之后跟的代码中有if的判断都没有通过。

我们接着看下一个步骤：

从注释我们知道这一步是告诉子类去刷新内部的bean工厂。

这个refreshBeanFactory方法什么都没干，就是设置了一个id。然后getBeanFactory方法就返回了一个DefaultListableBeanFactory。

下面继续看下一步：

这个就是设置了一系列的东西，自己下面看源码吧。

继续下一步：

下面这个图是上图中调用的父类方法：

经过debug我们发现basePackage和annotatedClasses都是空：

继续看下一个步骤：

刚才调试的时候遇到个疑问，当我运行完

这个方法之后，打印出来好几行日志，其中有一条：

已经加载了配置文件，但是在前面的调试过程中我并没有发现加载这个配置文件的过程呀，很有可能是我落掉了，于是从这条日志入手开始回溯，最终在

这里发现了源头，原来准备环境的时候就已经加载了配置文件，这里面有个

监听器的环境准备，一路跟下去到了这里：

当循环到ConfigFileApplicationLilstener的时候，执行了它的方法：

到了这里看注释就很明白了，就是添加配置文件到环境中。具体的看load方法：

这个方法中调用了另外一个带参数的load方法：

这里调用了一个getSearchlocations方法：

这是方法中用到的三个常量：

我的应用中前两个配置都没有，所以就用的第三个常量来查找，根据注释我们知道查找的顺序是从后往前，若多个路径下都存在配置文件则以最后一个为准，所以我们一般将配置文件就放在classpath路径下，保证以这个配置为准。

代码中还有一个方法：

如下：

其中用到的常量：

然后加载文件：

这里面要文件后缀，后缀是从PropertySourceLoader中获取的，我们看道propertySourceLoaders中有两个PropertySourceLoader，PropertiesPropertySourceLoader和YamlPropertySourceLoader，我们看看他们分别使用什么后缀：

总共有四种后缀，也就是说支持4中后缀的配置文件。后面就是加载的过程了，这里就不再深入了，下面再继续看吧。

我们继续看这个：

这个invoke的方法很长，我们慢慢看：

public static void invokeBeanFactoryPostProcessors(
      ConfigurableListableBeanFactory beanFactory, List beanFactoryPostProcessors) {

   // Invoke BeanDefinitionRegistryPostProcessors first, if any.
   Set processedBeans = new HashSet<>();

   if (beanFactory instanceof BeanDefinitionRegistry) {
      BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
      List regularPostProcessors = new ArrayList<>();
      List registryProcessors = new ArrayList<>();

      for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
         if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
            BeanDefinitionRegistryPostProcessor registryProcessor =
                  (BeanDefinitionRegistryPostProcessor) postProcessor;
            registryProcessor.postProcessBeanDefinitionRegistry(registry);
            registryProcessors.add(registryProcessor);
         }
         else {
            regularPostProcessors.add(postProcessor);
         }
      }

      // Do not initialize FactoryBeans here: We need to leave all regular beans
      // uninitialized to let the bean factory post-processors apply to them!
      // Separate between BeanDefinitionRegistryPostProcessors that implement
      // PriorityOrdered, Ordered, and the rest.
      List currentRegistryProcessors = new ArrayList<>();

      // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
      String[] postProcessorNames =
            beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
      for (String ppName : postProcessorNames) {
         if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
            currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
            processedBeans.add(ppName);
         }
      }
      sortPostProcessors(currentRegistryProcessors, beanFactory);
      registryProcessors.addAll(currentRegistryProcessors);
      invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
      currentRegistryProcessors.clear();

      // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
      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.
      boolean reiterate = true;
      while (reiterate) {
         reiterate = false;
         postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
         for (String ppName : postProcessorNames) {
            if (!processedBeans.contains(ppName)) {
               currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
               processedBeans.add(ppName);
               reiterate = true;
            }
         }
         sortPostProcessors(currentRegistryProcessors, beanFactory);
         registryProcessors.addAll(currentRegistryProcessors);
         invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
         currentRegistryProcessors.clear();
      }

      // Now, invoke the postProcessBeanFactory callback of all processors handled so far.
      invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
      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 priorityOrderedPostProcessors = new ArrayList<>();
   List orderedPostProcessorNames = new ArrayList<>();
   List 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 orderedPostProcessors = new ArrayList<>();
   for (String postProcessorName : orderedPostProcessorNames) {
      orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
   }
   sortPostProcessors(orderedPostProcessors, beanFactory);
   invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

   // Finally, invoke all other BeanFactoryPostProcessors.
   List nonOrderedPostProcessors = new ArrayList<>();
   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();
}

 

当运行到这里

的时候就正式进入了加载我们自己写的类的过程了：

这个方法也很大：

/**
 * Build and validate a configuration model based on the registry of
 * {@link Configuration} classes.
 */
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
   List configCandidates = new ArrayList<>();
   String[] candidateNames = registry.getBeanDefinitionNames();

   for (String beanName : candidateNames) {
      BeanDefinition beanDef = registry.getBeanDefinition(beanName);
      if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
            ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
         if (logger.isDebugEnabled()) {
            logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
         }
      }
      else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
         configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
      }
   }

   // Return immediately if no @Configuration classes were found
   if (configCandidates.isEmpty()) {
      return;
   }

   // Sort by previously determined @Order value, if applicable
   configCandidates.sort((bd1, bd2) -> {
      int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
      int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
      return Integer.compare(i1, i2);
   });

   // Detect any custom bean name generation strategy supplied through the enclosing application context
   SingletonBeanRegistry sbr = null;
   if (registry instanceof SingletonBeanRegistry) {
      sbr = (SingletonBeanRegistry) registry;
      if (!this.localBeanNameGeneratorSet) {
         BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
         if (generator != null) {
            this.componentScanBeanNameGenerator = generator;
            this.importBeanNameGenerator = generator;
         }
      }
   }

   if (this.environment == null) {
      this.environment = new StandardEnvironment();
   }

   // Parse each @Configuration class
   ConfigurationClassParser parser = new ConfigurationClassParser(
         this.metadataReaderFactory, this.problemReporter, this.environment,
         this.resourceLoader, this.componentScanBeanNameGenerator, registry);

   Set candidates = new LinkedHashSet<>(configCandidates);
   Set alreadyParsed = new HashSet<>(configCandidates.size());
   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
   if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
      sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
   }

   if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
      // Clear cache in externally provided MetadataReaderFactory; this is a no-op
      // for a shared cache since it'll be cleared by the ApplicationContext.
      ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
   }
}

当循环完毕上面的 7 个candidateNames之后：

configCondidates中只有我们自己的启动类。

接下来的parse方法才是真正开始解析。

在上图的 do 处调用了下图的方法：

从注释可以知道这个方法就是用来通过读取注解、成员、方法等来创建一个完全的配置类的。

这个方法很大：

/**
 * 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
 */
@Nullable
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
      throws IOException {

   if (configClass.getMetadata().isAnnotated(Component.class.getName())) {
      // Recursively process any member (nested) classes first
      processMemberClasses(configClass, sourceClass);
   }

   // 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 componentScans = AnnotationConfigUtils.attributesForRepeatable(
         sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
   if (!componentScans.isEmpty() &&
         !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
      for (AnnotationAttributes componentScan : componentScans) {
         // The config class is annotated with @ComponentScan -> perform the scan immediately
         Set 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), true);

   // Process any @ImportResource annotations
   AnnotationAttributes importResource =
         AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
   if (importResource != null) {
      String[] resources = importResource.getStringArray("locations");
      Class readerClass = importResource.getClass("reader");
      for (String resource : resources) {
         String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
         configClass.addImportedResource(resolvedResource, readerClass);
      }
   }

   // Process individual @Bean methods
   Set 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;
}

 

到了下图的方法处：

又是一个parse方法：

这个方法也很大：

public Set parse(AnnotationAttributes componentScan, final String declaringClass) {
   ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
         componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);

   Class generatorClass = componentScan.getClass("nameGenerator");
   boolean useInheritedGenerator = (BeanNameGenerator.class == generatorClass);
   scanner.setBeanNameGenerator(useInheritedGenerator ? this.beanNameGenerator :
         BeanUtils.instantiateClass(generatorClass));

   ScopedProxyMode scopedProxyMode = componentScan.getEnum("scopedProxy");
   if (scopedProxyMode != ScopedProxyMode.DEFAULT) {
      scanner.setScopedProxyMode(scopedProxyMode);
   }
   else {
      Class resolverClass = componentScan.getClass("scopeResolver");
      scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
   }

   scanner.setResourcePattern(componentScan.getString("resourcePattern"));

   for (AnnotationAttributes filter : componentScan.getAnnotationArray("includeFilters")) {
      for (TypeFilter typeFilter : typeFiltersFor(filter)) {
         scanner.addIncludeFilter(typeFilter);
      }
   }
   for (AnnotationAttributes filter : componentScan.getAnnotationArray("excludeFilters")) {
      for (TypeFilter typeFilter : typeFiltersFor(filter)) {
         scanner.addExcludeFilter(typeFilter);
      }
   }

   boolean lazyInit = componentScan.getBoolean("lazyInit");
   if (lazyInit) {
      scanner.getBeanDefinitionDefaults().setLazyInit(true);
   }

   Set basePackages = new LinkedHashSet<>();
   String[] basePackagesArray = componentScan.getStringArray("basePackages");
   for (String pkg : basePackagesArray) {
      String[] tokenized = StringUtils.tokenizeToStringArray(this.environment.resolvePlaceholders(pkg),
            ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
      Collections.addAll(basePackages, tokenized);
   }
   for (Class clazz : componentScan.getClassArray("basePackageClasses")) {
      basePackages.add(ClassUtils.getPackageName(clazz));
   }
   if (basePackages.isEmpty()) {
      basePackages.add(ClassUtils.getPackageName(declaringClass));
   }

   scanner.addExcludeFilter(new AbstractTypeHierarchyTraversingFilter(false, false) {
      @Override
      protected boolean matchClassName(String className) {
         return declaringClass.equals(className);
      }
   });
   return scanner.doScan(StringUtils.toStringArray(basePackages));
}

内容主要是设置scanner，我们直接看最后一行：

/**
 * Perform a scan within the specified base packages,
 * returning the registered bean definitions.
 * 
This method does not register an annotation config processor
 * but rather leaves this up to the caller.
 * @param basePackages the packages to check for annotated classes
 * @return set of beans registered if any for tooling registration purposes (never {@code null})
 */
protected Set doScan(String... basePackages) {
   Assert.notEmpty(basePackages, "At least one base package must be specified");
   Set beanDefinitions = new LinkedHashSet<>();
   for (String basePackage : basePackages) {
      Set candidates = findCandidateComponents(basePackage);
      for (BeanDefinition candidate : candidates) {
         ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
         candidate.setScope(scopeMetadata.getScopeName());
         String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
         if (candidate instanceof AbstractBeanDefinition) {
            postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
         }
         if (candidate instanceof AnnotatedBeanDefinition) {
            AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
         }
         if (checkCandidate(beanName, candidate)) {
            BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
            definitionHolder =
                  AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
            beanDefinitions.add(definitionHolder);
            registerBeanDefinition(definitionHolder, this.registry);
         }
      }
   }
   return beanDefinitions;
}

在上面方法体中的第四行处调用了下面的方法：

然后调用的第二个分支的代码：

从代码中可以看到传入的basePackage是come，这个是在上面的调用过程中解析出来的我们的主类所在的包的路径。

private Set scanCandidateComponents(String basePackage) {
   Set candidates = new LinkedHashSet<>();
   try {
      String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
            resolveBasePackage(basePackage) + '/' + this.resourcePattern;
      Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
      boolean traceEnabled = logger.isTraceEnabled();
      boolean debugEnabled = logger.isDebugEnabled();
      for (Resource resource : resources) {
         if (traceEnabled) {
            logger.trace("Scanning " + resource);
         }
         if (resource.isReadable()) {
            try {
               MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
               if (isCandidateComponent(metadataReader)) {
                  ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
                  sbd.setResource(resource);
                  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 (Throwable ex) {
               throw new BeanDefinitionStoreException(
                     "Failed to read candidate component class: " + resource, ex);
            }
         }
         else {
            if (traceEnabled) {
               logger.trace("Ignored because not readable: " + resource);
            }
         }
      }
   }
   catch (IOException ex) {
      throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
   }
   return candidates;
}

然后在方法体中的第三行代码拼接了要搜索的路径：

然后从改路径中获取类保存到数组中：

我们看到加载了5000多个类文件，其中就包括了我们自己写的类。

加载的过程：

这里是一个递归的调用，加载的过程用使用到了双亲委派模型，如下：

下图是一个中间过程，展示了获取到我们写的类路径下的东西：

下面这个方法是具体的读取路径下的类文件的，并且逐个读取类的名称、父类、接口、属性、方法等信息，这个方法在ClassReader类中，这个类是spring中的。它的原理就是将类文件读取到字符数组后，调用这个accept方法来逐个读取类信息的。

这个accept方法很大，内容很多，我觉得我没有获得其中的真谛，还是水平有限啊！！！

上面的doscan方法最后返回的：

我们写的类的东西。

后面还有很多内容，下面有时间再分析吧。