Spring配置Bean有多种形式，第一种常用的就是通过XML文件配置，另外一种就是通过@Configuration声明类，表明是一个配置文件，他的本质作用和XML是相同的，作为Bean的载体。今天我们来和大家聊一下Spring对Configuraion的解析。
首先我们先解释一些知识点，因为这些知识贯穿Spring初始化的始终。第一点，BeanFactoryPostProcessor的作用。允许修改spring容器中Bean的定义，也就是修改BeanDefinition。第二点，BeanDefinitionRegistryPostProcessor的作用，他继承了BeanFactoryPostProcessor，说明他拥有BeanFactoryPostProcessor的能力，除此之外，他和提供方法来注册新的BeanDefinition。第三点，Spring是在什么时候处理BeanFactoryPostProcessor呢？这个问题的答案可以看一下org.springframework.context.support.AbstractApplicationContext#invokeBeanFactoryPostProcessors的实现，应该不难看懂。
上面的知识点都了解之后，我们开始介绍我们今天的主角：ConfigurationClassPostProcessor。它实现了BeanDefinitionRegistryPostProcessor接口，所以他本身具有注册Bean的功能。那我们看看他的生命周期方法postProcessBeanDefinitionRegistry
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
...
processConfigBeanDefinitions(registry);
}
方法中只留下一个解析方法，无疑他就是理解解析的关键。下面我们来着重讲解
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<BeanDefinitionHolder>();
String[] candidateNames = registry.getBeanDefinitionNames();
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName); //关注点1
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)) {
//关注点2
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
Collections.sort(configCandidates, new Comparator<BeanDefinitionHolder>() {
@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
SingletonBeanRegistry singletonRegistry = null;
if (registry instanceof SingletonBeanRegistry) {
singletonRegistry = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet && singletonRegistry.containsSingleton(CONFIGURATION_BEAN_NAME_GENERATOR)) {
BeanNameGenerator generator = (BeanNameGenerator) singletonRegistry.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
// Parse each @Configuration class
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<BeanDefinitionHolder>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<ConfigurationClass>(configCandidates.size());
do {
//关注点3
parser.parse(candidates);
parser.validate();
Set<ConfigurationClass> configClasses = new LinkedHashSet<ConfigurationClass>(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());
}
//关注点4
this.reader.loadBeanDefinitions(configClasses);
alreadyParsed.addAll(configClasses);
candidates.clear();
if (registry.getBeanDefinitionCount() > candidateNames.length) {
String[] newCandidateNames = registry.getBeanDefinitionNames();
Set<String> oldCandidateNames = new HashSet<String>(Arrays.asList(candidateNames));
Set<String> alreadyParsedClasses = new HashSet<String>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
if (!oldCandidateNames.contains(candidateName)) {
BeanDefinition beanDef = registry.getBeanDefinition(candidateName);
if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(beanDef.getBeanClassName())) {
candidates.add(new BeanDefinitionHolder(beanDef, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
while (!candidates.isEmpty());
// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
if (singletonRegistry != null) {
if (!singletonRegistry.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
singletonRegistry.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
}
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
}
}
首先我们看下关注点1，从BeanDefinitionRegistry中根据名称获取到具体的BeanDefinition.然后经历了两个判断方法ConfigurationClassUtils.isFullConfigurationClass和ConfigurationClassUtils.isLiteConfigurationClass
他们的实现是根据具体的字符串和BeanDefinition中key为org.springframework.context.annotation.ConfigurationClassPostProcessor.configurationClass中的value进行比较得出的，此处可以先忽略，后面会有地方继续讲到。下面我们看下关注点2，spring是如何判断这个这个Bean是Configaration的，我们就得看看ConfigurationClassUtils.checkConfigurationClassCandidate
public static boolean checkConfigurationClassCandidate(BeanDefinition beanDef, MetadataReaderFactory metadataReaderFactory) {
String className = beanDef.getBeanClassName();
if (className == null) {
return false;
}
AnnotationMetadata metadata;
if (beanDef instanceof AnnotatedBeanDefinition &&
className.equals(((AnnotatedBeanDefinition) beanDef).getMetadata().getClassName())) {
// Can reuse the pre-parsed metadata from the given BeanDefinition...
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.
Class<?> beanClass = ((AbstractBeanDefinition) beanDef).getBeanClass();
metadata = new StandardAnnotationMetadata(beanClass, true);
}
else {
try {
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;
}
}
if (isFullConfigurationCandidate(metadata)) {
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL);
}
else if (isLiteConfigurationCandidate(metadata)) {
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE);
}
else {
return false;
}
// It's a full or lite configuration candidate... Let's determine the order value, if any.
Map<String, Object> orderAttributes = metadata.getAnnotationAttributes(Order.class.getName());
if (orderAttributes != null) {
beanDef.setAttribute(ORDER_ATTRIBUTE, orderAttributes.get(AnnotationUtils.VALUE));
}
return true;
}
这个方法的前半部分就是为了得到这个Bean对应的AnnotationMetadata。随后通过两个判断方法isFullConfigurationCandidate和isLiteConfigurationCandidate判断是否需要给BeanDefination中增加对应的键值对，其中键的定义就是就是我们关注点1中提到的org.springframework.context.annotation.ConfigurationClassPostProcessor.configurationClass。那么看看是具体怎么判断的
public static boolean isFullConfigurationCandidate(AnnotationMetadata metadata) {
return metadata.isAnnotated(Configuration.class.getName());
}
如果类上有@Configuration注解说明是一个完全（Full）的配置类。
public static boolean isLiteConfigurationCandidate(AnnotationMetadata metadata) {
// Do not consider an interface or an annotation...
if (metadata.isInterface()) {
return false;
}
// Any of the typical annotations found?
for (String indicator : candidateIndicators) {
if (metadata.isAnnotated(indicator)) {
return true;
}
}
// Finally, let's look for @Bean methods...
try {
return metadata.hasAnnotatedMethods(Bean.class.getName());
}
catch (Throwable ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to introspect @Bean methods on class [" + metadata.getClassName() + "]: " + ex);
}
return false;
}
}
如果是一个接口，那么不是简化（Lite）配置类，如果类上有candidateIndicators这个Set中定义的注解的话（@Component，@ComponentScan，@Import，@ImportResource）那么就是一个简化配置类，如果不是上面两种情况，那么有@Bean注解修饰的方法也是简化配置类。OK，目前为止我们可以知道Spring是怎么判断是一个配置类的，随后将配置类放入到configCandidates这个BeanDefinitionHolder的集合中存储，进行下一步的操作。有了这个集合，下面我们就可以创建一个配置文件的解析器ConfigurationClassParser类型的实例parser，进行解析（parse）。那我们看看关注点3，parse方法的实现。
public void parse(Set<BeanDefinitionHolder> configCandidates) {
this.deferredImportSelectors = new LinkedList<DeferredImportSelectorHolder>();
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 (Exception ex) {
throw new BeanDefinitionStoreException(
"Failed to parse configuration class [" + bd.getBeanClassName() + "]", ex);
}
}
processDeferredImportSelectors();
}
开头创建了一个LinkedList存放DeferredImportSelectorHolder，方法最后开始处理这个。中间的过程就是具体的解析过程，我们看一下。parse有很多歌重载，但是最终着眼于，根据入参，创建一个ConfigurationClass类型的实例，利用processConfigurationClass来处理这个ConfigurationClass类型的实例。我们继续看
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
...
// Recursively process the configuration class and its superclass hierarchy.
SourceClass sourceClass = asSourceClass(configClass);
do {
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
this.configurationClasses.put(configClass, configClass);
}
第一个操作是处理条件注解（@Conditional），如果不满足条件注解中的条件的定义，直接返回不进行下面的操作。将ConfigurationClass configClass类型的数据，转化成 SourceClass sourceClass = asSourceClass(configClass);
类型的sourceClass，随后doProcessConfigurationClass。
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass) throws IOException {
// Recursively process any member (nested) classes first
//关注点a
processMemberClasses(configClass, sourceClass);
// Process any @PropertySource annotations
//关注点b
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");
}
}
// Process any @ComponentScan annotations
//关注点c
AnnotationAttributes componentScan = AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ComponentScan.class);
if (componentScan != null && !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
// The config class is annotated with @ComponentScan -> perform the scan immediately
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 necessary
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
if (ConfigurationClassUtils.checkConfigurationClassCandidate(holder.getBeanDefinition(), this.metadataReaderFactory)) {
parse(holder.getBeanDefinition().getBeanClassName(), holder.getBeanName());
}
}
}
// Process any @Import annotations
//关注点d
processImports(configClass, sourceClass, getImports(sourceClass), true);
// Process any
// 关注点e
@ImportResource annotations
if (sourceClass.getMetadata().isAnnotated(ImportResource.class.getName())) {
AnnotationAttributes importResource = AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
String[] resources = importResource.getAliasedStringArray("locations", ImportResource.class, sourceClass);
Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
for (String resource : resources) {
String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
configClass.addImportedResource(resolvedResource, readerClass);
}
}
// Process individual
// 关注点f
@Bean methods
Set<MethodMetadata> beanMethods = sourceClass.getMetadata().getAnnotatedMethods(Bean.class.getName());
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
// Process default methods on interfaces
// 关注点 g
for (SourceClass ifc : sourceClass.getInterfaces()) {
beanMethods = ifc.getMetadata().getAnnotatedMethods(Bean.class.getName());
for (MethodMetadata methodMetadata : beanMethods) {
if (!methodMetadata.isAbstract()) {
// A default method or other concrete method on a Java 8+ interface...
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
}
}
// Process superclass, if any
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;
}
一个解析注解标签的大餐即将上演。首先看一下关注点a，解析成员类（内部类）
private void processMemberClasses(ConfigurationClass configClass, SourceClass sourceClass) throws IOException {
for (SourceClass memberClass : sourceClass.getMemberClasses()) {
if (ConfigurationClassUtils.isConfigurationCandidate(memberClass.getMetadata()) &&
!memberClass.getMetadata().getClassName().equals(configClass.getMetadata().getClassName())) {
if (this.importStack.contains(configClass)) {
this.problemReporter.error(new CircularImportProblem(configClass, this.importStack));
}
else {
this.importStack.push(configClass);
try {
processConfigurationClass(memberClass.asConfigClass(configClass));
}
finally {
this.importStack.pop();
}
}
}
}
}
找到所有的内部类，遍历判断内部类是否是配置文件类，如果是调用处理配置文件的方法processConfigurationClass处理。内部类处理完了，我们看下关注点b，怎么处理@PropertySources注解。如果Configration类上有@PropertySources注解的话，会调用processPropertySource方法处理
private void processPropertySource(AnnotationAttributes propertySource) throws IOException {
String name = propertySource.getString("name");
String[] locations = propertySource.getStringArray("value");
boolean ignoreResourceNotFound = propertySource.getBoolean("ignoreResourceNotFound");
Assert.isTrue(locations.length > 0, "At least one @PropertySource(value) location is required");
for (String location : locations) {
try {
String resolvedLocation = this.environment.resolveRequiredPlaceholders(location);
Resource resource = this.resourceLoader.getResource(resolvedLocation);
ResourcePropertySource rps = (StringUtils.hasText(name) ?
new ResourcePropertySource(name, resource) : new ResourcePropertySource(resource));
addPropertySource(rps);
}
catch (IllegalArgumentException ex) {
// from resolveRequiredPlaceholders
if (!ignoreResourceNotFound) {
throw ex;
}
}
catch (FileNotFoundException ex) {
// from ResourcePropertySource constructor
if (!ignoreResourceNotFound) {
throw ex;
}
}
}
}
操作很简单，根据注解中的value字段得到配置文件的路径，根据路径得到ResourcePropertySource类型的对象，里面包含已经加载成功的属性文件中的数据，随后调用addPropertySource方法，将配置属性添加到Enviroment中。属性文件处理成功后，我们看下关注点c,他要做的就是处理@ComponentScan注解，这个注解设计到的内容较多，后面会有文章进行详细的介绍，此处只是简单说一下他所做的事情：首先得到@ComponentScan实例，然后放入componentScanParser这个解析器中，得到被扫描进行的新的BeanDefinition,再次检查新加入的这些Bean有没有Configration类型的，如果有，继续调用parse方法，解析配置。此处@ComponentScan注解就解析完了，我们再看关注点d，他是如何解析@Import注解的。
首先我们看看他是如何收集Import注解的
private Set<SourceClass> getImports(SourceClass sourceClass) throws IOException {
Set<SourceClass> imports = new LinkedHashSet<SourceClass>();
Set<SourceClass> visited = new LinkedHashSet<SourceClass>();
collectImports(sourceClass, imports, visited);
return imports;
}
private void collectImports(SourceClass sourceClass, Set<SourceClass> imports, Set<SourceClass> visited) throws IOException {
if (visited.add(sourceClass)) {
for (SourceClass annotation : sourceClass.getAnnotations()) {
String annName = annotation.getMetadata().getClassName();
if (!annName.startsWith("java") && !annName.equals(Import.class.getName())) {
collectImports(annotation, imports, visited);
}
}
imports.addAll(sourceClass.getAnnotationAttributes(Import.class.getName(), "value"));
}
}
从配置类上得到所有的注解，遍历每一个注解，如果这个注解类的不是以java开头，另外也不是@Import的话，继续低估寻找，最后将找到的Import注解中的value的值放到imports这个集合中，当然最后返回的肯定也是imports这个集合了，所以寻找的过程是递归寻找@Import寻找。找到具体的要导入的资源了，我们看看他是怎么处理这些导入的
private void processImports(ConfigurationClass configClass, SourceClass currentSourceClass,
Collection<SourceClass> importCandidates, boolean checkForCircularImports) throws IOException {
if (importCandidates.isEmpty()) {
return;
}
if (checkForCircularImports && this.importStack.contains(configClass)) {
this.problemReporter.error(new CircularImportProblem(configClass, this.importStack));
}
else {
this.importStack.push(configClass);
try {
for (SourceClass candidate : importCandidates) {
if (candidate.isAssignable(ImportSelector.class)) {
// Candidate class is an ImportSelector -> delegate to it to determine imports
Class<?> candidateClass = candidate.loadClass();
ImportSelector selector = BeanUtils.instantiateClass(candidateClass, ImportSelector.class);
invokeAwareMethods(selector);
if (this.deferredImportSelectors != null && selector instanceof DeferredImportSelector) {
this.deferredImportSelectors.add(
new DeferredImportSelectorHolder(configClass, (DeferredImportSelector) selector));
}
else {
String[] importClassNames = selector.selectImports(currentSourceClass.getMetadata());
Collection<SourceClass> 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
Class<?> candidateClass = candidate.loadClass();
ImportBeanDefinitionRegistrar registrar =
BeanUtils.instantiateClass(candidateClass, ImportBeanDefinitionRegistrar.class);
invokeAwareMethods(registrar);
configClass.addImportBeanDefinitionRegistrar(registrar, currentSourceClass.getMetadata());
}
else {
// Candidate class not an ImportSelector or ImportBeanDefinitionRegistrar ->
// process it as an @Configuration class
this.importStack.registerImport(
currentSourceClass.getMetadata(), candidate.getMetadata().getClassName());
processConfigurationClass(candidate.asConfigClass(configClass));
}
}
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (Exception ex) {
throw new BeanDefinitionStoreException("Failed to process import candidates for configuration class [" +
configClass.getMetadata().getClassName() + "]", ex);
}
finally {
this.importStack.pop();
}
}
}
其实可以清晰的看到有三种情况，第一种导入的类是ImportSelector类型的。利用反射实例化这个类，随后将一些应该注入的注入进去，如果是DeferredImportSelector类型的，那么就放到deferredImportSelectors这个集合里，在文章的开篇我们声明了这个集合，可以到文章开头回顾下。如果不是这种类型的，就调用selectImports方法得到需要导入的类，随后继续递归此方法，进行导入。第二种是ImportBeanDefinitionRegistrar类型，一样利用反射进行初始化，随后注入属性，随后调用了configClass.addImportBeanDefinitionRegistrar添加进来了。最后一种情况导入的就是一个配置文件Configration类，直接调用processConfigurationClass方法进行处理。@Import注解就基本上说完了。随后我们看看关注点e，处理@ImportResource注解。这个操作也是比较简单，如果配置问价类上有@ImportResource注解，获取其中locations字段中的值，通过解析占位符等得到真正的路径，通过addImportedResource添加到configClass中。接着我们要处理的就是@Bean了，看一下关注点f.得到所有的利用@Bean注解声明的方法，利用addBeanMethod方法，将封装成BeanMethod类型的对象，添加到configClass中。针对java8的默认方法，spring也进行了支持，看一下关注点g,获取配置类上的所有的接口，如果接口中的方法有@Bean注解修饰，那么也会添加到configClass中。还有一个部分，我们提到了一个延迟的ImportSelector的集合deferredImportSelectors，因为上面的流程中有添加数据到这个结合中，最后我们看看他是如何处理的org.springframework.context.annotation.ConfigurationClassParser#processDeferredImportSelectors
private void processDeferredImportSelectors() {
List<DeferredImportSelectorHolder> deferredImports = this.deferredImportSelectors;
this.deferredImportSelectors = null;
Collections.sort(deferredImports, DEFERRED_IMPORT_COMPARATOR);
for (DeferredImportSelectorHolder deferredImport : deferredImports) {
ConfigurationClass configClass = deferredImport.getConfigurationClass();
try {
String[] imports = deferredImport.getImportSelector().selectImports(configClass.getMetadata());
processImports(configClass, asSourceClass(configClass), asSourceClasses(imports), false);
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (Exception ex) {
throw new BeanDefinitionStoreException("Failed to process import candidates for configuration class [" +
configClass.getMetadata().getClassName() + "]", ex);
}
}
}
和正常处理的没有太大的不同，可能就是为了延迟执行吧。获取到所有要导入的类，然后调用processImports方法进行真正的导入。OK，解析的流程我们就告一段落，将这个类中的所有的注解解析了一遍，有些数据也放到了configClass里面，还没有用到。下面我们再看看他是再哪里用到的。看一下org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader#loadBeanDefinitions的关注点4，创建了一个读取器，使用此读取器通过配置好的ConfigurationClass进行加载BeanDefinition
private void loadBeanDefinitionsForConfigurationClass(ConfigurationClass configClass,
TrackedConditionEvaluator trackedConditionEvaluator) {
if (trackedConditionEvaluator.shouldSkip(configClass)) {
String beanName = configClass.getBeanName();
if (StringUtils.hasLength(beanName) && this.registry.containsBeanDefinition(beanName)) {
this.registry.removeBeanDefinition(beanName);
}
this.importRegistry.removeImportingClassFor(configClass.getMetadata().getClassName());
return;
}
if (configClass.isImported()) {
registerBeanDefinitionForImportedConfigurationClass(configClass);
}
for (BeanMethod beanMethod : configClass.getBeanMethods()) {
loadBeanDefinitionsForBeanMethod(beanMethod);
}
loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
}
里面的registerBeanDefinitionForImportedConfigurationClass、loadBeanDefinitionsForBeanMethod、loadBeanDefinitionsFromImportedResources、loadBeanDefinitionsFromRegistrars分别做的事情时将此Configuration注册成了BeanDefinition,将配置文件里面的使用@Bean注释的方法变成了BeanDefinition，将ImportResource进来的配置文件加载解析，从资源文件加载合适的Bean,最后一个就是调用Config类中ImportBeanDefinitionRegistrar类型的对象的registerBeanDefinitions方法，实现他们内部的注册逻辑。
今天讲了一大通，终于把@Configuration注解的处理讲完了，希望可以帮助到需要的朋友。
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