protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
		Assert.notEmpty(basePackages, "At least one base package must be specified");
		Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
		// 可以指定多個(gè)basePackage,這里就對(duì)每個(gè)都處理
		for (String basePackage : basePackages) {
		  // 這個(gè)方法是真正的查找候選Bean的地方
			Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
			// 對(duì)于每個(gè)查找出的候選Bean，進(jìn)行處理
			for (BeanDefinition candidate : candidates) {
			  // 解析@Scope的元數(shù)據(jù)
				ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
				candidate.setScope(scopeMetadata.getScopeName());
				// 為候選的Bean生成一個(gè)名稱
				String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
				// 應(yīng)用后置處理器
				if (candidate instanceof AbstractBeanDefinition) {
					postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
				}
				// 
				// 處理一些其它通用的注解的元數(shù)據(jù)
				if (candidate instanceof AnnotatedBeanDefinition) {
					AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
				}
				// 校驗(yàn)通過(guò)后，注冊(cè)到 BeanFactory
				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;
	}

SimpleMetadataReader(Resource resource, @Nullable ClassLoader classLoader) throws IOException {
    // 通過(guò)流讀取資源的內(nèi)容，現(xiàn)在這個(gè)資源可以認(rèn)為是我們的類
		InputStream is = new BufferedInputStream(resource.getInputStream());
		ClassReader classReader;
		try {
		  // 這個(gè)Reader的構(gòu)造器中就將流讀取完畢了
			classReader = new ClassReader(is);
		}
		catch (IllegalArgumentException ex) {
		  // 通過(guò)這個(gè)異常的信息，可以推測(cè)出，其實(shí)這里是通過(guò)ASM讀取Class文件的定義了
			throw new NestedIOException("ASM ClassReader failed to parse class file - " +
					"probably due to a new Java class file version that isn't supported yet: " + resource, ex);
		}
		finally {
			is.close();
		}

    // 這里根據(jù)命名可以推測(cè)是訪問(wèn)者模式來(lái)暴露注解的元數(shù)據(jù)
		AnnotationMetadataReadingVisitor visitor = new AnnotationMetadataReadingVisitor(classLoader);

		// 這個(gè)accpect方法也是訪問(wèn)者模式中的典型方法，在這里面，是數(shù)據(jù)的解析邏輯
		classReader.accept(visitor, ClassReader.SKIP_DEBUG);

		this.annotationMetadata = visitor;
		// (since AnnotationMetadataReadingVisitor extends ClassMetadataReadingVisitor)
		this.classMetadata = visitor;
		this.resource = resource;
	}