invokeBeanFactoryPostProcessors

一、唠嗑

最近研究SpringBoot的源码，有了一个新的发现，这里把debug的整个过程先记录下来，只是记录过程，没有进行深入理解。或许有的人觉得没什么，你想想啊Spring最基础最牛逼的就是对bean的管理了，Spring所有的功能都是基于这个基础去扩展的。我这里找到了bean扫描和初始化的地方，这意味着如果研究透了这个过程和设计，对于Spring后面的理解就有基础了。哇哦..，这样你就可以很霸气的在简历上写上精通Spring，月薪过万都委屈你。

二、源码流程

1. ApplictionContext

扫描并注入bean 在 refreshContext中。

public ConfigurableApplicationContext run(String... args) {
	long startTime = System.nanoTime();
	DefaultBootstrapContext bootstrapContext = createBootstrapContext();
	ConfigurableApplicationContext context = null;
	configureHeadlessProperty();
	SpringApplicationRunListeners listeners = getRunListeners(args);
	listeners.starting(bootstrapContext, this.mainApplicationClass);
	try {
		ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
		ConfigurableEnvironment environment = prepareEnvironment(listeners, bootstrapContext, applicationArguments);
		configureIgnoreBeanInfo(environment);
		Banner printedBanner = printBanner(environment);
		context = createApplicationContext();
		context.setApplicationStartup(this.applicationStartup);
		prepareContext(bootstrapContext, context, environment, listeners, applicationArguments, printedBanner);
		// Spring 扫描到class并注入bean在这里面
		refreshContext(context);
		afterRefresh(context, applicationArguments);
		Duration timeTakenToStartup = Duration.ofNanos(System.nanoTime() - startTime);
		if (this.logStartupInfo) {
			new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), timeTakenToStartup);
		}
		listeners.started(context, timeTakenToStartup);
		callRunners(context, applicationArguments);
	}
	catch (Throwable ex) {
		handleRunFailure(context, ex, listeners);
		throw new IllegalStateException(ex);
	}
	try {
		Duration timeTakenToReady = Duration.ofNanos(System.nanoTime() - startTime);
		listeners.ready(context, timeTakenToReady);
	}
	catch (Throwable ex) {
		handleRunFailure(context, ex, null);
		throw new IllegalStateException(ex);
	}
	return context;
}
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2. AbstractApplicationContext

执行后置处理器 invokeBeanFactoryPostProcessors

@Override
public void refresh() throws BeansException, IllegalStateException {
	synchronized (this.startupShutdownMonitor) {
		StartupStep contextRefresh = this.applicationStartup.start("spring.context.refresh");
		prepareRefresh();
		ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
		prepareBeanFactory(beanFactory);
		try {
			postProcessBeanFactory(beanFactory);
			StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");
			// 看这里
			invokeBeanFactoryPostProcessors(beanFactory);
			registerBeanPostProcessors(beanFactory);
			beanPostProcess.end();
			initMessageSource();
			initApplicationEventMulticaster();
			onRefresh();
			registerListeners();
			finishBeanFactoryInitialization(beanFactory);
			finishRefresh();
		}

		catch (BeansException ex) {
			if (logger.isWarnEnabled()) {
				logger.warn("Exception encountered during context initialization - " +
						"cancelling refresh attempt: " + ex);
			}
			destroyBeans();
			cancelRefresh(ex);
			throw ex;
		}

		finally {
			resetCommonCaches();
			contextRefresh.end();
		}
	}
}
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3. PostProcessorRegistrationDelegate

继续进入到invokeBeanDefinitionRegistryPostProcessors，下面有很多这个方法，不过我已经在下面写注释了进行标识了。

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

		List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
		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);
		// 在这里
		invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
		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, beanFactory.getApplicationStartup());
		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, beanFactory.getApplicationStartup());
			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<>(orderedPostProcessorNames.size());
	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<>(nonOrderedPostProcessorNames.size());
	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();
}
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private static void invokeBeanDefinitionRegistryPostProcessors(
	Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry, ApplicationStartup applicationStartup) {
	for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
		StartupStep postProcessBeanDefRegistry = applicationStartup.start("spring.context.beandef-registry.post-process")
				.tag("postProcessor", postProcessor::toString);
		// 这里
		postProcessor.postProcessBeanDefinitionRegistry(registry);
		postProcessBeanDefRegistry.end();
	}
}
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4. ConfigurationClassParser

4.1 parse

public void parse(Set<BeanDefinitionHolder> configCandidates) {
	for (BeanDefinitionHolder holder : configCandidates) {
		BeanDefinition bd = holder.getBeanDefinition();
		try {
			if (bd instanceof AnnotatedBeanDefinition) {
				// 这里
				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();
}
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4.2 parse

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

下面的方法就到了扫描bean的地方了，在do while循环里面，这段代码。

protected void processConfigurationClass(ConfigurationClass configClass, Predicate<String> filter) throws IOException {
	if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
		return;
	}

	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);
			this.knownSuperclasses.values().removeIf(configClass::equals);
		}
	}

	// Recursively process the configuration class and its superclass hierarchy.
	// 看这里。
	SourceClass sourceClass = asSourceClass(configClass, filter);
	do {
		sourceClass = doProcessConfigurationClass(configClass, sourceClass, filter);
	}
	while (sourceClass != null);

	this.configurationClasses.put(configClass, configClass);
}
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4.4 SourceClass

在下面这行代码，就是找到被 @Configuration @Componce @Controller … 注释的类。哇哦~~

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

@Nullable
protected final SourceClass doProcessConfigurationClass(
		ConfigurationClass configClass, SourceClass sourceClass, Predicate<String> filter)
		throws IOException {

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

	// Process any @PropertySource annotations
	for (AnnotationAttributes propertySource : AnnotationConfigUtils.attributesForRepeatable(
			sourceClass.getMetadata(), PropertySources.class,
			org.springframework.context.annotation.PropertySource.class)) {
		if (this.environment instanceof ConfigurableEnvironment) {
			processPropertySource(propertySource);
		}
		else {
			logger.info("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() +
					"]. Reason: Environment must implement ConfigurableEnvironment");
		}
	}

	// Process any @ComponentScan annotations
	Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
			sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
	if (!componentScans.isEmpty() &&
			!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
		for (AnnotationAttributes componentScan : componentScans) {
			// The config class is annotated with @ComponentScan -> perform the scan immediately
			// 这里啊
			Set<BeanDefinitionHolder> scannedBeanDefinitions =
					this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
			// Check the set of scanned definitions for any further config classes and parse recursively if needed
			for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
				BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
				if (bdCand == null) {
					bdCand = holder.getBeanDefinition();
				}
				if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
					parse(bdCand.getBeanClassName(), holder.getBeanName());
				}
			}
		}
	}

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

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

	// Process individual @Bean methods
	Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
	for (MethodMetadata methodMetadata : beanMethods) {
		configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
	}

	// Process default methods on interfaces
	processInterfaces(configClass, sourceClass);

	// Process superclass, if any
	if (sourceClass.getMetadata().hasSuperClass()) {
		String superclass = sourceClass.getMetadata().getSuperClassName();
		if (superclass != null && !superclass.startsWith("java") &&
				!this.knownSuperclasses.containsKey(superclass)) {
			this.knownSuperclasses.put(superclass, configClass);
			// Superclass found, return its annotation metadata and recurse
			return sourceClass.getSuperClass();
		}
	}

	// No superclass -> processing is complete
	return null;
}
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6. ComponentScanAnnotationParser

6.1 parse

最后一行

return scanner.doScan(StringUtils.toStringArray(basePackages));

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

	Class<? extends BeanNameGenerator> 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<? extends ScopeMetadataResolver> resolverClass = componentScan.getClass("scopeResolver");
		scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
	}

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

	for (AnnotationAttributes includeFilterAttributes : componentScan.getAnnotationArray("includeFilters")) {
		List<TypeFilter> typeFilters = TypeFilterUtils.createTypeFiltersFor(includeFilterAttributes, this.environment,
				this.resourceLoader, this.registry);
		for (TypeFilter typeFilter : typeFilters) {
			scanner.addIncludeFilter(typeFilter);
		}
	}
	for (AnnotationAttributes excludeFilterAttributes : componentScan.getAnnotationArray("excludeFilters")) {
		List<TypeFilter> typeFilters = TypeFilterUtils.createTypeFiltersFor(excludeFilterAttributes, this.environment,
			this.resourceLoader, this.registry);
		for (TypeFilter typeFilter : typeFilters) {
			scanner.addExcludeFilter(typeFilter);
		}
	}

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

	Set<String> 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));
}
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7. ClassPathBeanDefinitionScanner

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) {
		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;
}
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8. ClassPathScanningCandidateComponentProvider

findCandidateComponents

public Set<BeanDefinition> findCandidateComponents(String basePackage) {
	if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
		return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
	}
	else {
		return scanCandidateComponents(basePackage);
	}
}
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scanCandidateComponents

private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
	Set<BeanDefinition> 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);
			}
			try {
				MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
				if (isCandidateComponent(metadataReader)) {
					ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
					sbd.setSource(resource);
					if (isCandidateComponent(sbd)) {
						if (debugEnabled) {
							logger.debug("Identified candidate component class: " + resource);
						}
						candidates.add(sbd);
					}
					else {
						if (debugEnabled) {
							logger.debug("Ignored because not a concrete top-level class: " + resource);
						}
					}
				}
				else {
					if (traceEnabled) {
						logger.trace("Ignored because not matching any filter: " + resource);
					}
				}
			}
			catch (FileNotFoundException ex) {
				if (traceEnabled) {
					logger.trace("Ignored non-readable " + resource + ": " + ex.getMessage());
				}
			}
			catch (Throwable ex) {
				throw new BeanDefinitionStoreException(
						"Failed to read candidate component class: " + resource, ex);
			}
		}
	}
	catch (IOException ex) {
		throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
	}
	return candidates;
}
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9. GeneriApplicationContext

getResources

最后一行return

@Override
public Resource[] getResources(String locationPattern) throws IOException {
	if (this.resourceLoader instanceof ResourcePatternResolver) {
		return ((ResourcePatternResolver) this.resourceLoader).getResources(locationPattern);
	}
	return super.getResources(locationPattern);
}
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10. AbstarctApplication

10.1 getResources

@Override
public Resource[] getResources(String locationPattern) throws IOException {
	return this.resourcePatternResolver.getResources(locationPattern);
}
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11. PathMatchingResourcePatternResolver

11.1 getResources

findPathMatchingResources 下面有注释

@Override
public Resource[] getResources(String locationPattern) throws IOException {
	Assert.notNull(locationPattern, "Location pattern must not be null");
	if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
		// a class path resource (multiple resources for same name possible)
		if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
			// a class path resource pattern
			// 这里
			return findPathMatchingResources(locationPattern);
		}
		else {
			// all class path resources with the given name
			return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
		}
	}
	else {
		// Generally only look for a pattern after a prefix here,
		// and on Tomcat only after the "*/" separator for its "war:" protocol.
		int prefixEnd = (locationPattern.startsWith("war:") ? locationPattern.indexOf("*/") + 1 :
				locationPattern.indexOf(':') + 1);
		if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
			// a file pattern
			return findPathMatchingResources(locationPattern);
		}
		else {
			// a single resource with the given name
			return new Resource[] {getResourceLoader().getResource(locationPattern)};
		}
	}
}
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findPathMatchingResources

到这里就差不多到底了，不过还有一层。

protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
	String rootDirPath = determineRootDir(locationPattern);
	String subPattern = locationPattern.substring(rootDirPath.length());
	Resource[] rootDirResources = getResources(rootDirPath);
	Set<Resource> result = new LinkedHashSet<>(16);
	for (Resource rootDirResource : rootDirResources) {
		rootDirResource = resolveRootDirResource(rootDirResource);
		URL rootDirUrl = rootDirResource.getURL();
		if (equinoxResolveMethod != null && rootDirUrl.getProtocol().startsWith("bundle")) {
			URL resolvedUrl = (URL) ReflectionUtils.invokeMethod(equinoxResolveMethod, null, rootDirUrl);
			if (resolvedUrl != null) {
				rootDirUrl = resolvedUrl;
			}
			rootDirResource = new UrlResource(rootDirUrl);
		}
		if (rootDirUrl.getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
			result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirUrl, subPattern, getPathMatcher()));
		}
		else if (ResourceUtils.isJarURL(rootDirUrl) || isJarResource(rootDirResource)) {
			result.addAll(doFindPathMatchingJarResources(rootDirResource, rootDirUrl, subPattern));
		}
		else {
			result.addAll(doFindPathMatchingFileResources(rootDirResource, subPattern));
		}
	}
	if (logger.isTraceEnabled()) {
		logger.trace("Resolved location pattern [" + locationPattern + "] to resources " + result);
	}
	return result.toArray(new Resource[0]);
}
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三、献上我的debug截图

在PathMatchingResourcePatternResolver类的findPathMatchingResources方法，完美对上。