Spring BeanDefinition的解析过程源码分析(下)
作者：互联网
前言
本文主要接上文Spring BeanDefinition的解析过程源码分析(上)
上文讲到准备调用refresh()，本文还是不会对refresh()方法中所有方法进行分析，还是围绕BeanDefinition的解析来分析，本文篇幅可能过长！
进入refresh()方法
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
prepareRefresh();
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
prepareBeanFactory(beanFactory);
try {
postProcessBeanFactory(beanFactory);
invokeBeanFactoryPostProcessors(beanFactory);
......
}
}
}
关键方法在于invokeBeanFactoryPostProcessors(beanFactory)的执行，先大致梳理一下 refresh()逻辑吧
prepareRefresh()准备一些刷新操作，然后obtainFreshBeanFactory()方法实际上就是获取上文Spring BeanDefinition的解析过程源码分析(上)中的下面这部分
然后调用invokeBeanFactoryPostProcessors(beanFactory)方法得到一些需要注册为Bean的class并存储在beanFactory的
对染这里还未执行invokeBeanFactoryPostProcessors(beanFactory)方法，这里在上文中Spring BeanDefinition的解析过程源码分析(上)中的this()、register(annotatedClasses)方法中就添加了这些元数据！那么下面我们开始执行invokeBeanFactoryPostProcessors(beanFactory);方法！
执行invokeBeanFactoryPostProcessors(beanFactory);
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//传入Bean工厂并获取容器中的Bean工厂后置处理器(注意这里Bean工厂后置处理器还没有初始化)
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
..........
}
PostProcessorRegistrationDelegate
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
//判断我们的beanFactory是否实现了BeanDefinitionRegistry
if (beanFactory instanceof BeanDefinitionRegistry) {
//强行把beanFactory转为BeanDefinitionRegistry
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
//保存BeanFactoryPostProcessor类型的后置处理器
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
//保存BeanDefinitionRegistryPostProcessor类型的后置处理器
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
//循环我们传递进来的beanFactoryPostProcessors
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//判断我们的后置处理器是不是BeanDefinitionRegistryPostProcessor
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
//进行强制转化
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//调用它的后置方法
registryProcessor.postProcessBeanDefinitionRegistry(registry);
//添加到我们用于保存的BeanDefinitionRegistryPostProcessor的集合中
registryProcessors.add(registryProcessor);
}
else {
//若没有实现BeanDefinitionRegistryPostProcessor接口，那么他就是BeanFactoryPostProcessor 把当前的后置处理器加入到regularPostProcessors中
regularPostProcessors.add(postProcessor);
}
}
//定义一个集合用户保存当前准备创建的BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
//第一步:去容器中获取BeanDefinitionRegistryPostProcessor的bean的处理器名称
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//循环上一步获取的BeanDefinitionRegistryPostProcessor的类型名称
for (String ppName : postProcessorNames) {
//判断是否实现了PriorityOrdered接口的
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
//显示的调用getBean()的方式获取出该对象然后加入到currentRegistryProcessors集合中去
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
//同时也加入到processedBeans集合中去
processedBeans.add(ppName);
}
}
//对currentRegistryProcessors集合中BeanDefinitionRegistryPostProcessor进行排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//把他加入到用于保存到registryProcessors中
registryProcessors.addAll(currentRegistryProcessors);
/**
* 在这里典型的BeanDefinitionRegistryPostProcessor就是ConfigurationClassPostProcessor
* 用于进行bean定义的加载 比如我们的包扫描，@import等
*/
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
//调用完之后，马上clear
currentRegistryProcessors.clear();
//下一步 又去容器中获取BeanDefinitionRegistryPostProcessor的bean的处理器名称
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//循环上一步获取的BeanDefinitionRegistryPostProcessor的类型名称
for (String ppName : postProcessorNames) {
//表示没有被处理过,且实现了Ordered接口的
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
//显示的调用getBean()的方式获取出该对象然后加入到currentRegistryProcessors集合中去
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
//同时也加入到processedBeans集合中去
processedBeans.add(ppName);
}
}
//对currentRegistryProcessors集合中BeanDefinitionRegistryPostProcessor进行排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//把他加入到用于保存到registryProcessors中
registryProcessors.addAll(currentRegistryProcessors);
//调用他的后置处理方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
//调用完之后，马上clear
currentRegistryProcessors.clear();
//调用没有实现任何优先级接口的BeanDefinitionRegistryPostProcessor
//定义一个重复处理的开关变量 默认值为true
boolean reiterate = true;
//第一次就可以进来
while (reiterate) {
//进入循环马上把开关变量给改为false
reiterate = false;
//去容器中获取BeanDefinitionRegistryPostProcessor的bean的处理器名称
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//循环上一步获取的BeanDefinitionRegistryPostProcessor的类型名称
for (String ppName : postProcessorNames) {
//没有被处理过的
if (!processedBeans.contains(ppName)) {
//显示的调用getBean()的方式获取出该对象然后加入到currentRegistryProcessors集合中去
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
//同时也加入到processedBeans集合中去
processedBeans.add(ppName);
//再次设置为true
reiterate = true;
}
}
//对currentRegistryProcessors集合中BeanDefinitionRegistryPostProcessor进行排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//把他加入到用于保存到registryProcessors中
registryProcessors.addAll(currentRegistryProcessors);
//调用他的后置处理方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
//进行clear
currentRegistryProcessors.clear();
}
//调用实现了BeanDefinitionRegistryPostProcessor的接口 他是他也同时实现了BeanFactoryPostProcessor的方法
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
//调用BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {//若当前的beanFactory没有实现了BeanDefinitionRegistry 直接调用beanFactoryPostProcessor接口的方法进行后置处理
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
//最后一步 获取容器中所有的 BeanFactoryPostProcessor
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
//保存BeanFactoryPostProcessor类型实现了priorityOrdered
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
//保存BeanFactoryPostProcessor类型实现了Ordered接口的
List<String> orderedPostProcessorNames = new ArrayList<>();
//保存BeanFactoryPostProcessor没有实现任何优先级接口的
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
//processedBeans包含的话，表示在上面处理BeanDefinitionRegistryPostProcessor的时候处理过了
if (processedBeans.contains(ppName)) {
// skip - already processed in first phase above
}
//判断是否实现了PriorityOrdered
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
}
//判断是否实现了Ordered
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
//没有实现任何的优先级接口的
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
//先调用BeanFactoryPostProcessor实现了PriorityOrdered接口的
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
//再调用BeanFactoryPostProcessor实现了Ordered.
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
//调用没有实现任何方法接口的
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();
}
别看这里这么多方法，这里重点我们看第一个invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry)方法！
切入invokeBeanDefinitionRegistryPostProcessors()方法
PostProcessorRegistrationDelegate
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}
执行postProcessBeanDefinitionRegistry(registry)方法
ConfigurationClassPostProcessor
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
......
//真正的解析我们的Bean定义
processConfigBeanDefinitions(registry);
}
这个方法就比较核心了，这个方法也就是找到符合Spring Bean规则的class如下！
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
//获取Spring IoC容器中目前所有Bean定义的名称
String[] candidateNames = registry.getBeanDefinitionNames();
//循环所有的Bean定义信息
for (String beanName : candidateNames) {
//通过Bean的名称来获取Bean的定义对象
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
//判断是否有没有解析过
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
//判断是否是配置类
// checkConfigurationClassCandidate()会判断一个是否是一个配置类,并为BeanDefinition设置属性为lite或者full。
//在这儿为BeanDefinition设置lite和full属性值是为了后面在使用
// 如果加了@Configuration，那么对应的BeanDefinition为full;
// 如果加了@Bean,@Component,@ComponentScan,@Import,@ImportResource这些注解，则为lite。
//lite和full均表示这个BeanDefinition对应的类是一个配置类
else if (ConfigurationClassUtils.checkConfiguration
ClassCandidate(beanDef, this.metadataReaderFactory)) {
//添加到候选的配置类集合中
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// 若没有找到配置类 直接返回
if (configCandidates.isEmpty()) {
return;
}
//对我们的配置类进行Order排序
configCandidates.sort((bd1, bd2) -> {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return Integer.compare(i1, i2);
});
//创建@CompentScan、@Import导入进来的bean名称的生成器
SingletonBeanRegistry sbr = null;
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet) {
// beanName的生成器，因为后面会扫描出所有加入到spring容器中calss类，然后把这些class
// 解析成BeanDefinition类，此时需要利用BeanNameGenerator为这些BeanDefinition生成beanName
BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
if (generator != null) {
//设置@CompentScan导入进来的bean的名称生成器
this.componentScanBeanNameGenerator = generator;
//设置@Import导入进来的bean的名称生成器
this.importBeanNameGenerator = generator;
}
}
}
if (this.environment == null) {
this.environment = new StandardEnvironment();
}
//创建一个配置类解析器对象
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
//创建一个集合用于保存我们的配置类BeanDefinitionHolder集合默认长度是配置类集合的长度
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
//创建一个集合用于保存我们的已经解析的配置类，长度默认为解析出来默认的配置类的集合长度
Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
do {
//真正的解析我们的配置类
parser.parse(candidates);
parser.validate();
//解析出来的配置类
Set<ConfigurationClass> 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());
}
//真正的把我们解析出来的配置类注册到容器中
this.reader.loadBeanDefinitions(configClasses);
//加入到已经解析的集合中
alreadyParsed.addAll(configClasses);
candidates.clear();
//判断我们Spring IoC容器中Bean的定义数量是否 > 候选原始的bean定义的个数
if (registry.getBeanDefinitionCount() > candidateNames.length) {
//获取所有的bean定义
String[] newCandidateNames = registry.getBeanDefinitionNames();
//原始的老的候选的bean定义
Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
Set<String> alreadyParsedClasses = new HashSet<>();
//赋值已经解析的
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
//表示当前循环的还没有被解析过
if (!oldCandidateNames.contains(candidateName)) {
//判断有没有被解析过
BeanDefinition bd = registry.getBeanDefinition(candidateName);
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(bd.getBeanClassName())) {
candidates.add(new BeanDefinitionHolder(bd, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
//存在没有解析过的 需要循环解析
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();
}
}
这里代码也挺多的，其核心代码在于parser.parse(candidates);和this.reader.loadBeanDefinitions(configClasses);
关于this.reader.loadBeanDefinitions(configClasses)放在文末讲
切入parser.parse(candidates);
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();
}
这里其实是根据BeanDefinition 的不同，传入不同的入参！核心调用的还是同一个方法processConfigurationClass()！
protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
//把我们的配置类源信息和beanName包装成一个ConfigurationClass对象
processConfigurationClass(new ConfigurationClass(metadata, beanName));
}
切入processConfigurationClass()
该方法主要就是循环调用doProcessConfigurationClass(configClass, sourceClass);方法将符合Bean特征的class添加到BeanDefinitionMap中，然后将配置类添加到configurationClasses中
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
//获取我们的配置类对象
ConfigurationClass existingClass = this.configurationClasses.get(configClass);
//传入的配置类是通过其他配置类的Import导入进来的
if (existingClass != null) {
if (configClass.isImported()) {
if (existingClass.isImported()) {
//需要合并配置
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);
}
}
// 处理配置类，由于配置类可能存在父类(若父类的全类名是以java开头的，则除外)，所有需要将configClass变成sourceClass去解析，然后返回sourceClass的父类。
// 如果此时父类为空，则不会进行while循环去解析，如果父类不为空，则会循环的去解析父类
// SourceClass的意义：简单的包装类，目的是为了以统一的方式去处理带有注解的类，不管这些类是如何加载的
SourceClass sourceClass = asSourceClass(configClass);
//真正的进行配置类的解析
do {
//解析我们的配置类
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
// 将解析的配置类存储起来，这样回到parse()方法时，能取到值
this.configurationClasses.put(configClass, configClass);
}
切入doProcessConfigurationClass(configClass, sourceClass);
@Nullable
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
throws IOException {
if (configClass.getMetadata().isAnnotated(Component.class.getName())) {
// 处理内部类，处理内部类时，最终还是调用doProcessConfigurationClass()方法
processMemberClasses(configClass, sourceClass);
}
//处理我们的@PropertySources注解的
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");
}
}
//处理@ComponentScan或者@ComponentScans注解
//从先找出类上的@ComponentScan和@ComponentScans注解的所有属性(例如basePackages等属性值)
Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() &&
!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
//循环解析（我们解析出来的AnnotationAttributes）
for (AnnotationAttributes componentScan : componentScans) {
//解析@ComponentScan和@ComponentScans配置的扫描的包所包含的类
// 比如 basePackages = com.tiantang.study, 那么在这一步会扫描出这个包及子包下的class，然后将其解析成BeanDefinition
// (BeanDefinition可以理解为等价于BeanDefinitionHolder)
//把我们扫描出来的类变为bean定义的集合
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
// 通过上一步扫描包com.tiantang.com下的类，有可能扫描出来的bean中可能也添加了ComponentScan或者ComponentScans注解.
//所以这里需要循环遍历一次，进行递归(parse)，继续解析，直到解析出的类上没有ComponentScan和ComponentScans
// (这时3.1这一步解析出componentScans为空列表，不会进入到if语句，递归终止)
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
if (bdCand == null) {
bdCand = holder.getBeanDefinition();
}
//判断当前扫描出来的bean定义是不是一个配置类,若是的话 直接进行递归解析
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
//递归解析
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
//处理Import注解注册的bean，这一步只会将import注册的bean变为ConfigurationClass,不会变成BeanDefinition
// 而是在loadBeanDefinitions()方法中变成BeanDefinition，再放入到BeanDefinitionMap中
// 关于Import注解,后面会单独写文章介绍
processImports(configClass, sourceClass, getImports(sourceClass), true);
//处理@ImportResource注解引入的
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);
}
}
//处理@Bean methods获取到我们配置类中所有标注了@Bean的方法
Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
//处理配置类接口的
processInterfaces(configClass, sourceClass);
//处理配置类的父类的
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();
}
}
//没有父类解析完成
return null;
}
其中有个很重要的方法this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());和ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)
先讲checkConfigurationClassCandidate，因为this.componentScanParser.parse方法调用栈比较长！
切入checkConfigurationClassCandidate
该方法是用来判断一个是否是一个配置类，并为BeanDefinition设置属性为lite或者full。如果加了@Configuration，那么对应的BeanDefinition为full，如果加了@Bean，@Component，@ComponentScan，@Import，@ImportResource这些注解，则为lite。lite和full均表示这个BeanDefinition对应的类是一个配置类。
public static boolean checkConfigurationClassCandidate(BeanDefinition beanDef, MetadataReaderFactory metadataReaderFactory) {
// ... 省略部分不重要的代码
if (isFullConfigurationCandidate(metadata)) {
// 含有@Configuration注解，那么对应的BeanDefinition的configurationClass属性值设置为full
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL);
}
else if (isLiteConfigurationCandidate(metadata)) {
// 含有@Bean,@Component,@ComponentScan,@Import,@ImportResource注解
// configurationClass属性值设置为lite
beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE);
}
else {
return false;
}
return true;
}
切入this.componentScanParser.parse()
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
//给扫描器设置beanName的生成器对象
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));
//设置bean的域代理模型
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"));
//设置ComponentScan对象的includeFilters包含的属性
for (AnnotationAttributes filter : componentScan.getAnnotationArray("includeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addIncludeFilter(typeFilter);
}
}
//设置ComponentScan对象的excludeFilters不包含的属性
for (AnnotationAttributes filter : componentScan.getAnnotationArray("excludeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addExcludeFilter(typeFilter);
}
}
//是否懒加载
boolean lazyInit = componentScan.getBoolean("lazyInit");
if (lazyInit) {
scanner.getBeanDefinitionDefaults().setLazyInit(true);
}
//包路径
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);
}
});
//真正的进行扫描解析
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
切入scanner.doScan(StringUtils.toStringArray(basePackages))
doScan方法主要是实现了扫描的逻辑，也就是通过findCandidateComponents(basePackage)方法扫描指定包下的符合Bean特征的class，然后存放到candidates ，然后通过一系列判断进入registerBeanDefinition方法，将符合Bean特征的Bean注册到beanDefinitionMap中去
//类路径Bean定义扫描器扫描给定包及其子包
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
//创建bean定义的holder对象用于保存扫描后生成的bean定义对象
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
//循环我们的包路径集合
for (String basePackage : basePackages) {
//调用父类ClassPathScanningCandidateComponentProvider的方法
//扫描给定类路径，获取符合条件的Bean定义
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
//遍历扫描到的Bean
for (BeanDefinition candidate : candidates) {
//获取@Scope注解的值，即获取Bean的作用域
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
//为Bean设置作用域
candidate.setScope(scopeMetadata.getScopeName());
为Bean生成名称。也就是设置我们的beanName
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
/如果扫描到的Bean不是Spring的注解Bean，则为Bean设置默认值，
//设置Bean的自动依赖注入装配属性等
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
//处理jsr250相关的组件
if (candidate instanceof AnnotatedBeanDefinition) {
//处理注解Bean中通用的注解，在分析注解Bean定义类读取器时已经分析过
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
//把我们解析出来的组件bean定义注册到Spring IoC容器中
if (checkCandidate(beanName, candidate)) {
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
//根据注解中配置的作用域，为Bean应用相应的代理模式
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
beanDefinitions.add(definitionHolder);
//注册到Spring IoC容器中
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
其中findCandidateComponents(basePackage)和registerBeanDefinition(definitionHolder, this.registry)方法尤为重要！
切入findCandidateComponents(basePackage)
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
else {
return scanCandidateComponents(basePackage);
}
}
执行scanCandidateComponents方法
该方法的核心逻辑就是在指定的包路径下，及其子包扫描符合规则的类，并收集为candidates返回
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
//补全扫描路径，扫描所有.class文件 classpath*:com/mydemo/**/*.class
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
//定位资源
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 {
//通过ASM获取class元数据，并封装在MetadataReader元数据读取器中
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
//判断该类是否符合@CompoentScan的过滤规则
//过滤匹配排除excludeFilters排除过滤器(可以没有),包含includeFilter中的包含过滤器（至少包含一个）。
if (isCandidateComponent(metadataReader)) {
//把元数据转化为 BeanDefinition
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
//判断是否是合格的bean定义
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
//加入到集合中
candidates.add(sbd);
}
else {
//不合格 不是顶级类、具体类
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + resource);
}
}
}
else {
//不符@CompoentScan过滤规则
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;
}
这里有个判断是否符合过滤规则的方法isCandidateComponent()
切入isCandidateComponent()
判断元信息读取器读取的类是否符合容器定义的注解过滤规则
//@CompoentScan的过滤规则支持5种 （注解、类、正则、aop、自定义）
protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {
//如果读取的类的注解在排除注解过滤规则中，返回false
for (TypeFilter tf : this.excludeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
return false;
}
}
//如果读取的类的注解在包含的注解的过滤规则中，则返回ture
for (TypeFilter tf : this.includeFilters) {
//判断当前类的注解是否match规则
if (tf.match(metadataReader, getMetadataReaderFactory())) {
//是否有@Conditional注解，进行相关处理
return isConditionMatch(metadataReader);
}
}
return false;
}
来都来了，看看match方法如何实现的吧！
tf.match()
@Override
public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory)
throws IOException {
//检查当前类的注解是否符合规律规则
if (matchSelf(metadataReader)) {
return true;
}
//check 类名是否符合规则
ClassMetadata metadata = metadataReader.getClassMetadata();
if (matchClassName(metadata.getClassName())) {
return true;
}
//如果有继承父类
if (this.considerInherited) {
String superClassName = metadata.getSuperClassName();
if (superClassName != null) {
// Optimization to avoid creating ClassReader for super class.
Boolean superClassMatch = matchSuperClass(superClassName);
if (superClassMatch != null) {
if (superClassMatch.booleanValue()) {
return true;
}
}
else {
// Need to read super class to determine a match...
try {
if (match(metadata.getSuperClassName(), metadataReaderFactory)) {
return true;
}
}
catch (IOException ex) {
logger.debug("Could not read super class [" + metadata.getSuperClassName() +
"] of type-filtered class [" + metadata.getClassName() + "]");
}
}
}
}
//如果有实现接口
if (this.considerInterfaces) {
for (String ifc : metadata.getInterfaceNames()) {
// Optimization to avoid creating ClassReader for super class
Boolean interfaceMatch = matchInterface(ifc);
if (interfaceMatch != null) {
if (interfaceMatch.booleanValue()) {
return true;
}
}
else {
// Need to read interface to determine a match...
try {
if (match(ifc, metadataReaderFactory)) {
return true;
}
}
catch (IOException ex) {
logger.debug("Could not read interface [" + ifc + "] for type-filtered class [" +
metadata.getClassName() + "]");
}
}
}
}
return false;
}
我们接着matchSelf方法深入
protected boolean matchSelf(MetadataReader metadataReader) {
//获取注解元数据
AnnotationMetadata metadata = metadataReader.getAnnotationMetadata();
//check 注解及其派生注解中是否包含@Component
//获取当前类的注解 metadata.hasAnnotation @Controller
//获取当前类的注解及其派生注解 metadata.hasAnnotation @Controller包含的@Component\@Documented等等
return metadata.hasAnnotation(this.annotationType.getName()) ||
(this.considerMetaAnnotations && metadata.hasMetaAnnotation(this.annotationType.getName()));
}
这段代码可以解决Spring发现@Configuration、@Controller、@Service这些注解修饰的类的，在这些注解底层都是使用@Component的派生注解，而spring通过metadata.hasMetaAnnotation()方法获取到这些注解包含@Component，所以都可以扫描到
执行registerBeanDefinition(definitionHolder, this.registry)
protected void registerBeanDefinition(BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry) {
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, registry);
}
public static void registerBeanDefinition(
BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)
throws BeanDefinitionStoreException {
// Register bean definition under primary name.
String beanName = definitionHolder.getBeanName();
registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
// Register aliases for bean name, if any.
String[] aliases = definitionHolder.getAliases();
if (aliases != null) {
for (String alias : aliases) {
registry.registerAlias(beanName, alias);
}
}
}
registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
BeanDefinition existingDefinition = this.beanDefinitionMap.get(beanName);
if (existingDefinition != null) {
......
}
else {
if (hasBeanCreationStarted()) {
// Cannot modify startup-time collection elements anymore (for stable iteration)
synchronized (this.beanDefinitionMap) {
this.beanDefinitionMap.put(beanName, beanDefinition);
List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
updatedDefinitions.addAll(this.beanDefinitionNames);
updatedDefinitions.add(beanName);
this.beanDefinitionNames = updatedDefinitions;
if (this.manualSingletonNames.contains(beanName)) {
Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);
updatedSingletons.remove(beanName);
this.manualSingletonNames = updatedSingletons;
}
}
}
else {
// Still in startup registration phase
this.beanDefinitionMap.put(beanName, beanDefinition);
this.beanDefinitionNames.add(beanName);
this.manualSingletonNames.remove(beanName);
}
this.frozenBeanDefinitionNames = null;
}
if (existingDefinition != null || containsSingleton(beanName)) {
resetBeanDefinition(beanName);
}
}
那么这里this.beanDefinitionMap.put(beanName, beanDefinition);就是添加beanDefinitionMap中的核心方法
切入this.reader.loadBeanDefinitions(configClasses)
该方法实际上是将通过@Import、@Bean等注解方式注册的类解析成BeanDefinition，然后注册到BeanDefinitionMap中。
public void loadBeanDefinitions(Set<ConfigurationClass> configurationModel) {
TrackedConditionEvaluator trackedConditionEvaluator = new TrackedConditionEvaluator();
// 循环调用loadBeanDefinitionsForConfigurationClass()
for (ConfigurationClass configClass : configurationModel) {
loadBeanDefinitionsForConfigurationClass(configClass, trackedConditionEvaluator);
}
}
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.removeImportingClass(configClass.getMetadata().getClassName());
return;
}
// 如果一个bean是通过@Import(ImportSelector)的方式添加到容器中的，那么此时configClass.isImported()返回的是true
// 而且configClass的importedBy属性里面存储的是ConfigurationClass就是将bean导入的类
//是不是通过@Import导入进来的
if (configClass.isImported()) {
registerBeanDefinitionForImportedConfigurationClass(configClass);
}
// 判断当前的bean中是否含有@Bean注解的方法，如果有，需要把这些方法产生的bean放入到BeanDefinitionMap当中
for (BeanMethod beanMethod : configClass.getBeanMethods()) {
loadBeanDefinitionsForBeanMethod(beanMethod);
}
//是不是通过@ImportResources导入进来的
loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
// 如果bean上存在@Import注解，且import的是一个实现了ImportBeanDefinitionRegistrar接口,则执行ImportBeanDefinitionRegistrar的registerBeanDefinitions()方法，也就是判断是不是通过ImportBeanDefinition注解导入进来的
loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
}
registerBeanDefinitionForImportedConfigurationClass(configClass);
通过@Import导入进来的执行registerBeanDefinitionForImportedConfigurationClass(configClass)方法：
private void registerBeanDefinitionForImportedConfigurationClass(ConfigurationClass configClass) {
//获取我们的配置类的源信息
AnnotationMetadata metadata = configClass.getMetadata();
//构建为我们的bean定义
AnnotatedGenericBeanDefinition configBeanDef = new AnnotatedGenericBeanDefinition(metadata);
//设置他的scope
ScopeMetadata scopeMetadata = scopeMetadataResolver.resolveScopeMetadata(configBeanDef);
configBeanDef.setScope(scopeMetadata.getScopeName());
//获取bean的名称
String configBeanName = this.importBeanNameGenerator.generateBeanName(configBeanDef, this.registry);
//处理我们的JRS250组件的
AnnotationConfigUtils.processCommonDefinitionAnnotations(configBeanDef, metadata);
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(configBeanDef, configBeanName);
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
//注册我们的bean定义到我们的容器中
this.registry.registerBeanDefinition(definitionHolder.getBeanName(), definitionHolder.getBeanDefinition());
configClass.setBeanName(configBeanName);
if (logger.isDebugEnabled()) {
logger.debug("Registered bean definition for imported class '" + configBeanName + "'");
}
}
loadBeanDefinitionsForBeanMethod(beanMethod);
通过@Bean导入进来的执行loadBeanDefinitionsForBeanMethod(beanMethod)方法：
private void loadBeanDefinitionsForBeanMethod(BeanMethod beanMethod) {
ConfigurationClass configClass = beanMethod.getConfigurationClass();
MethodMetadata metadata = beanMethod.getMetadata();
String methodName = metadata.getMethodName();
.......
this.registry.registerBeanDefinition(beanName, beanDefToRegister);
}
这里又将符合Bean特征的class添加到BeanDefinitionMap中，那么至此整个invokeBeanFactoryPostProcessors(beanFactory);方法就至此完了！这里把符合Bean特征的class解析成BeanDefinition存储在beanFactory中
然后后期通过finishBeanFactoryInitialization(beanFactory)方法实例化这些Bean的操作！
标签：configClass,beanFactory,Spring,Bean,源码,registry,new,class,BeanDefinition 来源： https://blog.csdn.net/CSDN877425287/article/details/123564497