为什么这里会创建一个DefaultListableBeanFactory()实例的beanFactory？ 1.这个beanFactory主要是用来存放Spring管理的Bean对象，一个Bean存放的工厂。 2.怎么会调用了这步new DefaultListableBeanFactory()？
因为AnnotationConfigApplicationContext继承了GenericApplicationContext，即在创建AnnotationConfigApplicationContext对象，会先执行父类GenericApplicationContext的构造方法。所以这里是在父类的构造方法中，执行了new DefaultListableBeanFactory()创建了一个beanFactory对象。 public GenericApplicationContext() { this.beanFactory = new DefaultListableBeanFactory(); }
AnnotationConfigApplicationContext 继承了GenericApplicationContext GenericApplicationContext 实现了 BeanDefinitionRegistry
即有：AnnotationConfigApplicationContext 也实现了BeanDefinitionRegistry，AnnotationConfigApplicationContext 也是一个registry类。这个registry比较重要，registry有registerBeanDefinition（注册一个bean定义到bean工厂）、getBeanDefinition（从bean工厂获取一个Bean定义）等功能。所以AnnotationConfigApplicationContext 也是有可以往bean工厂中注册bean的能力。
//创建一个bean读取器过程分析：
this.reader = new AnnotatedBeanDefinitionReader(this);
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
this(registry, getOrCreateEnvironment(registry));
}
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
this.registry = registry; //将registry赋值
this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
//主要方法
registerAnnotationConfigProcessors(registry, null);
}
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(BeanDefinitionRegistry registry, @Nullable Object source) {
//获取到刚创建完的DefaultListableBeanFactory对象，然后给这个对象的某些属性赋值。
DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
if (beanFactory != null) {
if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
//AnnotationAwareOrderComparator主要能解析@Order注解和@Priority
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
}
if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
//ContextAnnotationAutowireCandidateResolver提供处理延迟加载的功能
beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
}
}
//给Spring容器添加Spring内部的特殊Bean对象（7个）
//1.往BeanDefinitionMap注册一个ConfigurationClassPostProcessor
Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);
//BeanDefinitio的注册，这里很重要，需要理解注册每个bean的类型
if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
//需要注意的是ConfigurationClassPostProcessor的类型是BeanDefinitionRegistryPostProcessor
//而 BeanDefinitionRegistryPostProcessor 最终实现BeanFactoryPostProcessor这个接口
RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
}
//2.往BeanDefinitionMap注册一个AutowiredAnnotationBeanPostProcessor
if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
//AutowiredAnnotationBeanPostProcessor 实现了 MergedBeanDefinitionPostProcessor
//MergedBeanDefinitionPostProcessor 最终实现了 BeanPostProcessor
RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
//3.往BeanDefinitionMap注册一个RequiredAnnotationBeanPostProcessor
if (!registry.containsBeanDefinition(REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(RequiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
//4.往BeanDefinitionMap注册一个CommonAnnotationBeanPostProcessor
// Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
}
//5.往BeanDefinitionMap注册一个PersistenceAnnotationBeanPostProcessor
// Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor.
if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition();
try {
def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
AnnotationConfigUtils.class.getClassLoader()));
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
}
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
}
//6.往BeanDefinitionMap注册一个EventListenerMethodProcessor
if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
}
//7.往BeanDefinitionMap注册一个DefaultEventListenerFactory
if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
}
return beanDefs;
}
//将**Processor类型的对象，注册到bean工厂中
private static BeanDefinitionHolder registerPostProcessor(BeanDefinitionRegistry registry, RootBeanDefinition definition, String beanName) {
definition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
//这里主要的代码，将bean定义注册到bean工厂当中
registry.registerBeanDefinition(beanName, definition);
return new BeanDefinitionHolder(definition, beanName);
}
复制代码这里创建一个AnnotatedBeanDefinitionReader对象，主要是做了2个主要的操作： 1.给在GenericApplicationContext()刚创建的beanFactory对象的某些属性赋值：
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);（主要能解析@Order注解和@Priority） beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());（提供处理延迟加载的功能）
2.往bean工厂中注册6个spring内部对象，主要是**BeanPostProcessor类型的对象。（Spring的扩展点之一）
这里特别重要的类是ConfigurationClassPostProcessor，这个类完成bean的扫描。
- （2）ac.register(AppConfig.class);
/**
* 注册单个bean给容器
* 比如有新加的类可以用这个方法
* 但是注册之后需要手动调用refresh方法去触发容器解析注解
*
* 有两个意思：
* 他可以注册一个配置类
* 他还可以单独注册一个bean
*/
public void register(Class<?>... annotatedClasses) {
this.reader.register(annotatedClasses);
}
public void register(Class<?>... annotatedClasses) {
for (Class<?> annotatedClass : annotatedClasses) {
registerBean(annotatedClass);
}
}
public void registerBean(Class<?> annotatedClass) {
//真正的注册bean的方法
doRegisterBean(annotatedClass, null, null, null);
}
<T> void doRegisterBean(Class<T> annotatedClass, @Nullable Supplier<T> instanceSupplier, @Nullable String name,
@Nullable Class<? extends Annotation>[] qualifiers, BeanDefinitionCustomizer... definitionCustomizers) {
/**
* 根据指定的bean创建一个AnnotatedGenericBeanDefinition
* 这个AnnotatedGenericBeanDefinition可以理解为一个数据结构
* AnnotatedGenericBeanDefinition包含了类的其他信息,比如一些元信息：scope，lazy等等
*/
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
/**
* 判断这个类是否需要跳过解析
* 通过代码可以知道spring判断是否跳过解析，主要判断类有没有加注解
*/
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
//不知道
abd.setInstanceSupplier(instanceSupplier);
/**
* 得到类的作用域
*/
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
/**
* 把类的作用域添加到数据结构结构中
*/
abd.setScope(scopeMetadata.getScopeName());
/**
* 生成类的名字通过beanNameGenerator
*/
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
/**
* 处理类当中的通用注解
* 分析源码可以知道他主要处理
* Lazy DependsOn Primary Role等等注解
* 处理完成之后processCommonDefinitionAnnotations中依然是把他添加到数据结构当中
*/
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
/**
* 如果在向容器注册注解Bean定义时，使用了额外的限定符注解则解析
* 关于Qualifier和Primary前面的课当中讲过，主要涉及到spring的自动装配
* 这里需要注意的
* byName和qualifiers这个变量是Annotation类型的数组，里面存不仅仅是Qualifier注解
* 理论上里面里面存的是一切注解，所以可以看到下面的代码spring去循环了这个数组
* 然后依次判断了注解当中是否包含了Primary，是否包含了Lazyd
*/
if (qualifiers != null) {
for (Class<? extends Annotation> qualifier : qualifiers) {
////如果配置了@Primary注解，如果加了则作为首选
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
//懒加载，前面加过
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
else {
//如果使用了除@Primary和@Lazy以外的其他注解，则为该Bean添加一个根据名字自动装配的限定符
//这里难以理解，后面会详细介绍
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
for (BeanDefinitionCustomizer customizer : definitionCustomizers) {
customizer.customize(abd);
}
/**
* 这个BeanDefinitionHolder也是一个数据结构（beanName，beanDefinition，aliases[]）
*/
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
/**
* ScopedProxyMode 这个知识点比较复杂，需要结合web去理解
*/
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
/**
* 把上述的这个数据结构注册给registry
* registy就是AnnotatonConfigApplicationContext
* AnnotatonConfigApplicationContext在初始化的時候通过调用父类的构造方法
* 实例化了一个DefaultListableBeanFactory
* *registerBeanDefinition里面就是把definitionHolder这个数据结构包含的信息注册到
* DefaultListableBeanFactory这个工厂
*/
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
//将beanDefinition注册到bean工厂中
public static void registerBeanDefinition(BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)throws BeanDefinitionStoreException{
String beanName = definitionHolder.getBeanName();
registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
String[] aliases = definitionHolder.getAliases();
if (aliases != null) {
for (String alias : aliases) {
registry.registerAlias(beanName, alias);
}
}
}
//DefaultListableBeanFactory
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
//主要代码：
this.beanDefinitionMap.put(beanName, beanDefinition);
this.beanDefinitionNames.add(beanName);
this.manualSingletonNames.remove(beanName);
}
复制代码ac.register(AppConfig.class);的主要作用是将AppConfig类注册到bean工厂中。 即是到目前为止，bean工厂中已经有了7个beanDefinition。
- （3）ac.refresh(); 这里最重要的一步，实现bean的扫描和初始化阶段
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
//准备工作包括设置启动时间，是否激活标识位，
// 初始化属性源(property source)配置
prepareRefresh();
//返回一个factory 为什么需要返回一个工厂
//因为要对工厂进行初始化
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
//准备工厂
prepareBeanFactory(beanFactory);
try {
//这个方法在当前版本的spring是没用任何代码的
//可能spring期待在后面的版本中去扩展吧
postProcessBeanFactory(beanFactory);
//在spring的环境中去执行已经被注册的 factoryBean processors
//设置执行自定义的ProcessBeanFactory 和spring内部自己定义的 （重要，实现bean的扫描等）
invokeBeanFactoryPostProcessors(beanFactory);
//注册beanPostProcessor
registerBeanPostProcessors(beanFactory);
initMessageSource();
//初始化应用事件广播器
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
//实例化单列的bean对象（重要）
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
finishRefresh();
}
catch (BeansException ex) {
throw ex;
}
}
}
复制代码- prepareRefresh
protected void prepareRefresh() {
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isInfoEnabled()) {
logger.info("Refreshing " + this);
}
// Initialize any placeholder property sources in the context environment
//这个方法目前没有子类去实现
//估计spring是期待后面的版本有子类去实现吧
initPropertySources();
// Validate that all properties marked as required are resolvable
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
this.earlyApplicationEvents = new LinkedHashSet<>();
}
复制代码- obtainFreshBeanFactory
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
refreshBeanFactory();
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (logger.isDebugEnabled()) {
logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
}
return beanFactory;
}
//GenericApplicationContext
@Override
public final ConfigurableListableBeanFactory getBeanFactory() {
return this.beanFactory;
}
复制代码- prepareBeanFactory
/**
* 配置其标准的特征，比如上下文的加载器ClassLoader和post-processors回调
* 此处的beanFactory参数等于DefaultListableFactory
*/
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
beanFactory.setBeanClassLoader(getClassLoader());
//bean表达式解释器，能够获取bean当中的属性在前台页面
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
//对象与string类型的转换 <property red="dao">
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
//添加一个后置管理器
//ApplicationContextAwareProcessor 能够在bean中获得到各种*Aware（*Aware都有其作用）
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
//意思就是：使得ApplicationContextAware接口实现类在自动装配时不能被注入applicationContext对象的依赖。
//（不能使用xml的set方法或构造方式注入，但是可以用@Autowired注入）
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// BeanFactory interface not registered as resolvable type in a plain factory.
// MessageSource registered (and found for autowiring) as a bean.
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// Register early post-processor for detecting inner beans as ApplicationListeners.
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// Set a temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
//意思是如果自定义的Bean中没有名为"systemProperties"和"systemEnvironment"的Bean，
// 则注册两个Bena，Key为"systemProperties"和"systemEnvironment"，Value为Map，
// 这两个Bean就是一些系统配置和系统环境信息
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
//直接往beanFactory工厂中添加bean对象（该对象已经被new出来的）
beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
}
if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
}
}
public void registerSingleton(String beanName, Object singletonObject) throws IllegalStateException {
synchronized (this.singletonObjects) {
Object oldObject = this.singletonObjects.get(beanName);
if (oldObject != null) {
throw new IllegalStateException();
}
addSingleton(beanName, singletonObject);
}
}
//往singletonObjects对象中添加bean实例
protected void addSingleton(String beanName, Object singletonObject) {
synchronized (this.singletonObjects) {
this.singletonObjects.put(beanName, singletonObject);
this.singletonFactories.remove(beanName);
this.earlySingletonObjects.remove(beanName);
this.registeredSingletons.add(beanName);
}
}
复制代码prepareBeanFactory方法的主要作用： 1.给beanFactory的某些属性赋值。 2.给beanFactory添加BeanPostProcessor：ApplicationContextAwareProcessor（可以插手bean的初始化，扩展点之一） 3.给beanFactory添加系统配置和系统环境信息等实例。
- invokeBeanFactoryPostProcessors
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//这个地方需要注意getBeanFactoryPostProcessors()是获取手动给spring的BeanFactoryPostProcessor
//自定义并不仅仅是程序员自己写的
//自己写的可以加companent也可以不加
//如果加了getBeanFactoryPostProcessors()这个地方得不得，是spring自己扫描的
//为什么得不到getBeanFactoryPostProcessors（）这个方法是直接获取一个list，
//这个list是在AnnotationConfigApplicationContext被定义
//所谓的自定义的就是你手动调用AnnotationConfigApplicationContext.addBeanFactoryPostProcesor();
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
}
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
Set<String> processedBeans = new HashSet<>();
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
//定义了两个list存放
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
//自定义的beanFactoryPostProcessors
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}else {
regularPostProcessors.add(postProcessor);
}
}
//这个currentRegistryProcessors 放的是spring内部自己实现了BeanDefinitionRegistryPostProcessor接口的对象
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
//BeanDefinitionRegistryPostProcessor 等于 BeanFactoryPostProcessor
//getBeanNamesForType 根据bean的类型获取bean的名字ConfigurationClassPostProcessor
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//这个地方可以得到一个BeanFactoryPostProcessor，因为是spring默认在最开始自己注册的
//为什么要在最开始注册这个呢？
//因为spring的工厂需要许解析去扫描等等功能
//而这些功能都是需要在spring工厂初始化完成之前执行
//要么在工厂最开始的时候、要么在工厂初始化之中，反正不能再之后
//因为如果在之后就没有意义，因为那个时候已经需要使用工厂了
//所以这里spring'在一开始就注册了一个BeanFactoryPostProcessor，用来插手springfactory的实例化过程
//在这个地方断点可以知道这个类叫做ConfigurationClassPostProcessor
//ConfigurationClassPostProcessor那么这个类能干嘛呢？可以参考源码
//下面我们对这个牛逼哄哄的类（他能插手spring工厂的实例化过程还不牛逼吗？）重点解释
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//排序不重要，况且currentRegistryProcessors这里也只有一个数据
sortPostProcessors(currentRegistryProcessors, beanFactory);
//合并list，不重要(为什么要合并，因为还有自己的)
registryProcessors.addAll(currentRegistryProcessors);
//最重要。注意这里是方法调用
//执行所有BeanDefinitionRegistryPostProcessor（开始执行扫描包）
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
//执行完成了所有BeanDefinitionRegistryPostProcessor
//这个list只是一个临时变量，故而要清除
currentRegistryProcessors.clear();
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.
//执行BeanFactoryPostProcessor的回调，前面不是吗？
//前面执行的BeanFactoryPostProcessor的子类BeanDefinitionRegistryPostProcessor的回调
//这是执行的是BeanFactoryPostProcessor postProcessBeanFactory
//ConfuguratuonClassPpostProcssor
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
//自定义BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 这里为什么要再重复执行一遍？
// 因为经过上面的ConfuguratuonClassPpostProcssor对bean的扫描，扫描到的bean对象有可能是实现了BeanFactoryPostProcessor接口的，所以要这这些扫描处理的bena进行再一步处理
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
//ConfigurationClassPostProcessor
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();
}
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
//因为只有一条数据：ConfigurationClassPostProcessor
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}
//ConfigurationClassPostProcessor
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException();
}
if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException();
}
this.registriesPostProcessed.add(registryId);
//执行
processConfigBeanDefinitions(registry);
}
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
//定义一个list存放app 提供的bd（项目当中提供了@Compent）
List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
//获取容器中注册的所有bd名字
//7个
String[] candidateNames = registry.getBeanDefinitionNames();
/**
* Full ， Lite
*/
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
//果BeanDefinition中的configurationClass属性为full或者lite,则意味着已经处理过了,直接跳过
//这里需要结合下面的代码才能理解
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
//判断是否是Configuration类，如果加了Configuration下面的这几个注解就不再判断了
// 还有 add(Component.class.getName());
// candidateIndicators.add(ComponentScan.class.getName());
// candidateIndicators.add(Import.class.getName());
// candidateIndicators.add(ImportResource.class.getName());
//beanDef == appconfig
else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
//BeanDefinitionHolder 也可以看成一个数据结构
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// 排序，根据order,不重要
// Sort by previously determined @Order value, if applicable
configCandidates.sort((bd1, bd2) -> {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return Integer.compare(i1, i2);
});
SingletonBeanRegistry sbr = null;
//如果BeanDefinitionRegistry是SingletonBeanRegistry子类的话,
// 由于我们当前传入的是DefaultListableBeanFactory,是SingletonBeanRegistry 的子类
// 因此会将registry强转为SingletonBeanRegistry
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet) {
//是否有自定义的
BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
//SingletonBeanRegistry中有id为 org.springframework.context.annotation.internalConfigurationBeanNameGenerator
//如果有则利用他的，否则则是spring默认的
if (generator != null) {
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
}
//实例化ConfigurationClassParser 为了解析各个配置类
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
//实例化2个set,candidates用于将之前加入的configCandidates进行去重
//因为可能有多个配置类重复了
//alreadyParsed用于判断是否处理过
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
do {
//很重要（扫描bean）
parser.parse(candidates);
parser.validate();
//map.keyset
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());
}
/**
* 这里值得注意的是扫描出来的bean当中可能包含了特殊类
* 比如ImportBeanDefinitionRegistrar那么也在这个方法里面处理
* 但是并不是包含在configClasses当中
* configClasses当中主要包含的是importSelector
* 因为ImportBeanDefinitionRegistrar在扫描出来的时候已经被添加到一个list当中去了
*/
//bd 到 map 除却普通 （将import的bean注册到bean工厂）（重要）
this.reader.loadBeanDefinitions(configClasses);
alreadyParsed.addAll(configClasses);
candidates.clear();
//由于我们这里进行了扫描，把扫描出来的BeanDefinition注册给了factory
if (registry.getBeanDefinitionCount() > candidateNames.length) {
String[] newCandidateNames = registry.getBeanDefinitionNames();
Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
Set<String> alreadyParsedClasses = new HashSet<>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
if (!oldCandidateNames.contains(candidateName)) {
BeanDefinition bd = registry.getBeanDefinition(candidateName);
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(bd.getBeanClassName())) {
candidates.add(new BeanDefinitionHolder(bd, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
}
//ConfigurationClassParser
public void parse(Set<BeanDefinitionHolder> configCandidates) {
this.deferredImportSelectors = new LinkedList<>();
//根据BeanDefinition 的类型 做不同的处理,一般都会调用ConfigurationClassParser#parse 进行解析
for (BeanDefinitionHolder holder : configCandidates) {
BeanDefinition bd = holder.getBeanDefinition();
try {
if (bd instanceof AnnotatedBeanDefinition) {
//解析注解对象，并且把解析出来的bd放到map，但是这里的bd指的是普通的
//何谓不普通的呢？比如@Bean 和各种beanFactoryPostProcessor得到的bean不在这里put
//但是是这里解析，只是不put而已
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());
}
}
}
//处理延迟加载的importSelect？为什么要延迟加载，估计就是为了延迟吧
processDeferredImportSelectors();
}
protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
processConfigurationClass(new ConfigurationClass(metadata, beanName));
}
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
// 处理Imported 的情况
// 就是当前这个注解类有没有被别的类import
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 imports.
// 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.
SourceClass sourceClass = asSourceClass(configClass);
do {
//具体的实现（重要）
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
//一个map，用来存放扫描出来的bean（注意这里的bean不是对象，仅仅bean的信息，因为还没到实例化这一步）
this.configurationClasses.put(configClass, configClass);
}
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
throws IOException {
// 处理内部类
processMemberClasses(configClass, sourceClass);
// 处理@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);
}
}
// 处理@ComponentScan注解
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) {
//扫描普通类=componentScan=com.llsydn
//这里扫描出来所有@Component
//并且把扫描的出来的普通bean放到map当中
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
//检查扫描出来的类当中是否还有configuration
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
if (bdCand == null) {
bdCand = holder.getBeanDefinition();
}
//检查到有的，再执行一次parse方法
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
/**
* 上面的代码就是扫描普通类[email protected]
* 并且放到了map当中
*/
// Process any @Import annotations
//处理@Import imports 3种情况
//ImportSelector
//普通类
//ImportBeanDefinitionRegistrar
//这里和内部地柜调用时候的情况不同
/**
* 这里处理的import是需要判断我们的类当中时候有@Import注解
* 如果有这把@Import当中的值拿出来，是一个类
* 比如@Import(xxxxx.class)，那么这里便把xxxxx传进去进行解析
* 在解析的过程中如果发觉是一个importSelector那么就回调selector的方法
* 返回一个字符串（类名），通过这个字符串得到一个类
* 继而在递归调用本方法来处理这个类
*
* 判断一组类是不是imports（3种import）
*/
processImports(configClass, sourceClass, getImports(sourceClass), 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);
}
}
// 处理@Bean方法
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;
}
//ComponentScanAnnotationParser，扫描普通的@component
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);
//扫描包（重点）
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
//ClassPathBeanDefinitionScanner
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
for (String basePackage : basePackages) {
//扫描basePackage路径下的java文件
//符合条件的并把它转成BeanDefinition类型
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
for (BeanDefinition candidate : candidates) {
//解析scope属性
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
if (candidate instanceof AbstractBeanDefinition) {
//如果这个类是AbstractBeanDefinition的子类
//则为他设置默认值，比如lazy，init destory
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
if (candidate instanceof AnnotatedBeanDefinition) {
//检查并且处理常用的注解
//这里的处理主要是指把常用注解的值设置到AnnotatedBeanDefinition当中
//当前前提是这个类必须是AnnotatedBeanDefinition类型的，说白了就是加了注解的类
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
if (checkCandidate(beanName, candidate)) {
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
beanDefinitions.add(definitionHolder);
//将bean定义注册到bean工厂中
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
//扫描包，将class转成beanDefinition
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
else {
return scanCandidateComponents(basePackage);
}
}
//利用asm技术读取class文件，并将class文件转成beanDefinition
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
//asm 读取class文件
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (Resource resource : resources) {
if (resource.isReadable()) {
try {
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
if (isCandidateComponent(sbd)) {
candidates.add(sbd);
}
}
}
}
}
}
return candidates;
}invokeBeanFactoryPostProcessors的主要作用： 1.执行spring内部的**BeanFactoryPostProcessor的方法。（ConfigurationClassPostProcessor）
ConfigurationClassPostProcessor主要的作用就是实现bean的扫描，并实现将beanDefinition注册到bean工厂中
BeanFactoryPostProcessor spring的扩展点之一： 1.实现该接口，可以在spring的bean创建之前修改bean的定义属性。 2.spring允许BeanFactoryPostProcessor在容器实例化任何其它bean之前读取配置元数据， 3.并可以根据需要进行修改，例如可以把bean的scope从singleton改为prototype，也可以把property的值给修改掉。 4.可以同时配置多个BeanFactoryPostProcessor，并通过设置'order'属性来控制各个BeanFactoryPostProcessor的执行次序。 5.BeanFactoryPostProcessor是在spring容器加载了bean的定义文件之后，在bean实例化之前执行的。
BeanDefinitionRegistryPostProcessor实现了BeanFactoryPostProcessor 。是对BeanFactoryPostProcessor 的扩展，新增了postProcessBeanDefinitionRegistry方法，可以往Bean工厂中，注册一个BeanDefinition对象。