Spring Boot2 源码 run > refreshContext > invokeBeanFactoryPostProcessors方法 （六）

11.5 调用BeanFactoryPostProcessor各个实现类的方法

先说明两个类的关系
1.BeanFactoryPostProcessor：用来修改Spring容器中已经存在的bean的定义，使用ConfigurableListableBeanFactory对bean进行处理
2.BeanDefinitionRegistryPostProcessor：继承BeanFactoryPostProcessor，作用跟BeanFactoryPostProcessor一样，只不过是使用BeanDefinitionRegistry对bean进行处理
3.先处理BeanDefinitionRegistryPostProcessor类，然后在处理BeanFactoryPostProcessor类

BeanDefinitionRegistryPostProcessor处理过程

1.实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor先全部找出来，然后排序后依次执行
2.实现Ordered接口的BeanDefinitionRegistryPostProcessor找出来，然后排序后依次执行
3.没有实现PriorityOrdered和Ordered接口的BeanDefinitionRegistryPostProcessor找出来执行并依次执行
4.执行是指postProcessBeanDefinitionRegistry

BeanFactoryPostProcessor处理过程

1.实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor先全部找出来，然后排序后依次执行
2.实现Ordered接口的BeanDefinitionRegistryPostProcessor找出来，然后排序后依次执行
3.没有实现PriorityOrdered和Ordered接口的BeanDefinitionRegistryPostProcessor找出来执行并依次执行
4.执行是指postProcessBeanFactory

源码比较长

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

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

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

			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<BeanDefinitionRegistryPostProcessor> 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<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {
			if (processedBeans.contains(ppName)) {
				// skip - already processed in first phase above
			}
			else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
			}
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

		// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

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

优先级最高的是ConfigurationClassPostProcessor，有兴趣的可以关注一下，import ComponentScan PropertySource 都是此类加载的

由于源码太长了，导致文章长度太长，我只截部分源码了，哪里有问题自己源码查看 版本 2.1.3.RELEASE

ConfigurationClassParser并不注册bean定义，主要是发现或者说放到对应的 Map中，后面调用者会根据不同得map注册bean定义，ConfigurationClassParser 并不是会将所有的类发现，同样 componentScanParser解析发现 @Component注解
 

ConfigurationClassParser parse()方法
跟据Bean定义的不同类型走不同的分支，但是最终都会调用到parse方法

public void parse(Set<BeanDefinitionHolder> configCandidates) {
		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);
			}
		}

		this.deferredImportSelectorHandler.process();
	}

 

doProcessConfigurationClass循环+递归发现

protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
		
		// 从当前配置类configClass开始向上沿着类继承结构逐层执行doProcessConfigurationClass,
	    // 直到遇到的父类是由Java提供的类结束循环
		SourceClass sourceClass = asSourceClass(configClass);
		do {
                // 循环处理配置类configClass直到sourceClass变为null
		// doProcessConfigurationClass的返回值是其参数configClass的父类，
		// 如果该父类是由Java提供的类或者已经处理过，返回null
			sourceClass = doProcessConfigurationClass(configClass, sourceClass);
		}
		while (sourceClass != null);
                //需要被处理的配置类configClass已经被分析处理，将它记录到已处理配置类记录
		this.configurationClasses.put(configClass, configClass);
	}

一个配置类的成员类(配置类内嵌套定义的类)也可能适配类，先遍历这些成员配置类，调用processConfigurationClass处理它们;
处理配置类上的注解@PropertySources,@PropertySource
处理配置类上的注解@ComponentScans,@ComponentScan
处理配置类上的注解@Import
处理配置类上的注解@ImportResource
处理配置类中每个带有@Bean注解的方法
处理配置类所实现接口的缺省方法
检查父类是否需要处理，如果父类需要处理返回父类，否则返回null 

 

/**
 * Apply processing and build a complete 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 null if none found or previously processed
 */
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
		throws IOException {

	// Recursively process any member (nested) classes first，首先递归处理嵌套类
	processMemberClasses(configClass, sourceClass);

	// Process any @PropertySource annotations，处理每个@PropertySource注解
	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");
		}
	}

	// 这里是根据启动类 @ComponentScan 注解来扫描项目中的bean
	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) {
			// ①该配置类上注解了@ComponentScan,现在执行扫描，获取其中的Bean定义
			// 通过componentScanParser获取scannedBeanDefinitions的值 
            //会将你的项目的所有类包含@Component或者间接包含的类注入到容器中
			Set<BeanDefinitionHolder> scannedBeanDefinitions =
					this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
			// 对Component scan得到的Bean定义做检查，看看里面是否有需要处理的配置类，
			// 有的话对其做分析处理
            //遍历我们项目中的bean，如果是注解定义的bean，则进一步解析
			for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
                //判断是否是注解bean
				if (ConfigurationClassUtils.checkConfigurationClassCandidate(
						holder.getBeanDefinition(), this.metadataReaderFactory)) {
					// 如果该Bean定义是一个配置类，它进行分析
					parse(holder.getBeanDefinition().getBeanClassName(), holder.getBeanName());
				}
			}
		}
	}

	//递归解析处理每个@Import注解	
	// 注意这里调用到了getImports()方法，它会搜集sourceClass上所有的@Import注解的value值，
	// 具体搜集的方式是访问sourceClass直接注解的@Import以及递归访问它的注解中隐含的所有的@Import	
	processImports(configClass, sourceClass, getImports(sourceClass), true);

	// Process any @ImportResource annotations，处理每个@ImportResource注解
	if (sourceClass.getMetadata().isAnnotated(ImportResource.class.getName())) {
		AnnotationAttributes importResource =
				AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
		String[] resources = importResource.getStringArray("locations");
		Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
		for (String resource : resources) {
			String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
			configClass.addImportedResource(resolvedResource, readerClass);
		}
	}

	// Process individual @Bean methods,处理配置类中每个带有@Bean注解的方法
	Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
	for (MethodMetadata methodMetadata : beanMethods) {
		configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
	}

	// Process default methods on interfaces，处理接口上的缺省方法
	processInterfaces(configClass, sourceClass);

	// Process superclass, if any
	// 如果父类superclass存在，并且不是`java`包中的类，并且尚未处理处理，
	// 则才返回它以便外层循环继续
	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，没找到需要处理的父类，处理结果
	return null;// 用返回null告诉外层循环结束
}

说下this.componentScanParser 这个是重点，为什么加个@Component注解就会加入到容器中，全部是这的作用，会加载你所有@Component注解或者是间接注解的类都会加入到容器中 扫描到就会加入到容器

                Set<BeanDefinitionHolder> scannedBeanDefinitions =
                        this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());

                scanner.doScan(StringUtils.toStringArray(basePackages))

protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
		Assert.notEmpty(basePackages, "At least one base package must be specified");
		Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
		for (String basePackage : basePackages) {
                //candidates 会包含你所有的类
                //basePackages 默认是启动类的包路径 我的启动类是在com.bjsdzk.api包下
                //他会搜索（classpath*:com/bjsdzk/api/**/*.class）路径下的
			Set<BeanDefinition> 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;
	}