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源码分析
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-config.xml");
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public ClassPathXmlApplicationContext(String configLocation) throws BeansException {
this(new String[] {configLocation}, true, null);
}
public ClassPathXmlApplicationContext(
String[] configLocations, boolean refresh, @Nullable ApplicationContext parent)
throws BeansException {
super(parent);
//解析并设置给定的资源路径数组
setConfigLocations(configLocations);
if (refresh) {
refresh();
}
}
上面的就是ClassPathXmlApplicationContext
加载的源码总览,下面逐步分析
一、解析并设置给定的资源路径数组
对应方法为setConfigLocations
public void setConfigLocations(@Nullable String... locations) {
if (locations != null) {
Assert.noNullElements(locations, "Config locations must not be null");
this.configLocations = new String[locations.length];
for (int i = 0; i < locations.length; i++) {
//这里是解析每个给定的路径,例如包含特殊符号的解析(${var})
this.configLocations[i] = resolvePath(locations[i]).trim();
}
}
else {
this.configLocations = null;
}
}
该方法就是解析配置路径,如果包含系统变量,则会调用resolvePath
方法进行解析
二、refresh方法(核心逻辑)
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
//1、准备刷新上下文环境
//获取容器的当前时间,同时给容器设置同步标识
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
//2、初始化BeanFactory,并进行XML文件的读取
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
//3、对BeanFactory进行各种功能的填充
//进入该方法前,Spring已经完成了对配置的解析,而ApplicationContext在功能上的扩展也由此展开
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
//4、子类覆盖方法做额外的处理
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
//5、激活各种BeanFactory处理器
//BeanFactoryPostProcessor接口可以在实例化任何bean之前获取配置信息,从而可以正确解析bean描述文件中的变量引用
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
//6、注册拦截Bean创建的Bean处理器(这里只是注册,真正的调用在bean实例化的时候)
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
//7、为上下文初始化Message源(即不同语言的消息体,国际化处理)
initMessageSource();
// Initialize event multicaster for this context.
//8、初始化应用消息广播器
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
//9、留给子类来初始化其它的Bean
onRefresh();
// Check for listener beans and register them.
//10、在所有注册的bean中查找Listener bean,并注册到消息广播器中
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
//11、初始化剩下的单实例(非懒加载的)
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
//12、完成刷新过程,通知生命周期处理器lifecycleProcessor刷新过程,
//同时发出ContextRefreshEvent通知别人
finishRefresh();
}
//13、异常之后的处理
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
//销毁已创建的单例
destroyBeans();
// Reset 'active' flag.
//重置active标志
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
//14、清除内置缓存
resetCommonCaches();
}
}
}
refresh方法是ClassPathXmlApplicationContext
加载的核心方法,内部逻辑大约分为以下14步
1、准备刷新上下文环境
protected void prepareRefresh() {
// Switch to active.
//记录启动开始时间
this.startupDate = System.currentTimeMillis();
//设置Context的当前状态
this.closed.set(false);
this.active.set(true);
if (logger.isDebugEnabled()) {
if (logger.isTraceEnabled()) {
logger.trace("Refreshing " + this);
}
else {
logger.debug("Refreshing " + getDisplayName());
}
}
// Initialize any placeholder property sources in the context environment.
//初始化上下文环境中的占位符属性来源
//这个方法是空实现,用户可以根据自身的需要重写该方法,并且在方法中进行个性化的属性处理及设置
initPropertySources();
// Validate that all properties marked as required are resolvable:
// see ConfigurablePropertyResolver#setRequiredProperties
//对属性进行必要的验证,验证需要的属性文件是否都已经放入环境中
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
if (this.earlyApplicationListeners == null) {
this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// Reset local application listeners to pre-refresh state.
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
this.earlyApplicationEvents = new LinkedHashSet<>();
}
该方法主要做一些准备工作
- 记录启动开始时间
- 设置上下文的状态
- 方法
initPropertySources
,用户可以自定义属性的处理和设置 - 对属性进行必要性的校验
- 初始化监听器及事件集合
2、初始化BeanFactory
,并进行配置文件的读取
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
//初始化BeanFactory,并进行XML文件读取,
//并将得到的BeanFactory记录在当前实体的属性中
refreshBeanFactory();
//返回当前实体的BeanFactory属性
return getBeanFactory();
}
这里主要是创建ConfigurableListableBeanFactory
类型的BeanFactory
并返回,核心逻辑在方法refreshBeanFactory
中,代码如下
protected final void refreshBeanFactory() throws BeansException {
//如果容器已经存在一个BeanFactory,则对其进行销毁和关闭
if (hasBeanFactory()) {
//銷毀单例bean
destroyBeans();
//关闭BeanFactory
closeBeanFactory();
}
try {
//创建DefaultListableBeanFactory类型的beanFactory
DefaultListableBeanFactory beanFactory = createBeanFactory();
//设置序列化Id(目的是为了需要根据Id反序列化出BeanFactory对象)
beanFactory.setSerializationId(getId());
//定制beanFactory,设置相关属性
//包括:
//(1)是否允许覆盖同名称的不同定义的对象
//(2)循环依赖
//(3)设置@Autowared和@Qualifier注解解析器QualifierAnnotationAutowireCandidateResolver
//子类可以覆盖该方法来进行自定义的设置
customizeBeanFactory(beanFactory);
//加载BeanDefinition
loadBeanDefinitions(beanFactory);
//使用全局变量记录beanFactory类实例
synchronized (this.beanFactoryMonitor) {
this.beanFactory = beanFactory;
}
}
catch (IOException ex) {
throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
}
}
主要做了以下两件事
- 对已有的
BeanFactory
进行销毁和关闭- 销毁单例bean
- 关闭当前
BeanFactory
- 创建并初始化新的
BeanFactory
(DefaultListableBeanFactory
类型)-
实例化
DefaultListableBeanFactory
类型的BeanFactory
-
设置序列化Id
-
定制定制
beanFactory
,设置相关属性,包括如下:(customizeBeanFactory
方法)- (1)是否允许覆盖同名称的不同定义的对象
- (2)循环依赖
- (3)设置@
Autowared
和@Qualifier
注解解析器
protected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) { //如果allowBeanDefinitionOverriding不为空,则设置给beanFactory //属性含义:是否允许覆盖同名称的不同定义的对象 if (this.allowBeanDefinitionOverriding != null) { beanFactory.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding); } //如果allowCircularReferences不为空,则设置给beanFactory //属性含义:是否允许bean之间存在循环依赖 if (this.allowCircularReferences != null) { beanFactory.setAllowCircularReferences(this.allowCircularReferences); } }
子类可以覆盖该方法来进行自定义的设置
-
加载
BeanDefinition
根据不同的子类解析配置文件或注解
-
使用全局变量记录
beanFactory
类实例
-
3、对BeanFactory
进行各种功能的填充
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
//设置beanFactory的classLoader为当前context的classLoader
beanFactory.setBeanClassLoader(getClassLoader());
//设置beanFactory的表达式语言处理器(Spring 3增加的表达式语言的支持)
//默认可以使用#{bean.xxx}的形式来调用相关的属性值
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
//创建默认的propertyEditorRegistrar,主要是对bean的属性等设置管理的一个工具(属性编辑器)
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
//添加ApplicationContextAwareProcessor
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
//设置几个忽略自动装配的接口
//这些接口会在执行ApplicationContextAwareProcessor时自动装配执行
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.
//设置几个自动装配的接口
//一般检测到指定类型的属性,就会自动装配上去
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()));
}
// Register default environment beans.
//增加对AspectJ的支持
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
//添加默认的系统环境bean
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());
}
}
-
设置
beanFactory
的classLoader
为当前context
的classLoader
-
设置
beanFactory
的表达式语言处理器,例如可以使用#{bean.xxx}
来调用相关属性 -
创建默认的
propertyEditorRegistrar
,主要是对bean
的属性等设置管理的一个工具(属性编辑器)这里创建的属性编辑器为默认的
ResourceEditorRegistrar
类型,在该类中存在这样的代码public void registerCustomEditors(PropertyEditorRegistry registry) { ResourceEditor baseEditor = new ResourceEditor(this.resourceLoader, this.propertyResolver); doRegisterEditor(registry, Resource.class, baseEditor); doRegisterEditor(registry, ContextResource.class, baseEditor); doRegisterEditor(registry, InputStream.class, new InputStreamEditor(baseEditor)); doRegisterEditor(registry, InputSource.class, new InputSourceEditor(baseEditor)); doRegisterEditor(registry, File.class, new FileEditor(baseEditor)); doRegisterEditor(registry, Path.class, new PathEditor(baseEditor)); doRegisterEditor(registry, Reader.class, new ReaderEditor(baseEditor)); doRegisterEditor(registry, URL.class, new URLEditor(baseEditor)); ClassLoader classLoader = this.resourceLoader.getClassLoader(); doRegisterEditor(registry, URI.class, new URIEditor(classLoader)); doRegisterEditor(registry, Class.class, new ClassEditor(classLoader)); doRegisterEditor(registry, Class[].class, new ClassArrayEditor(classLoader)); if (this.resourceLoader instanceof ResourcePatternResolver) { doRegisterEditor(registry, Resource[].class, new ResourceArrayPropertyEditor((ResourcePatternResolver) this.resourceLoader, this.propertyResolver)); } }
可以看到Spring为我们定义了一些基本属性的编辑器。
-
添加
ApplicationContextAwareProcessor
类型的后置处理器,它的作用是invoke
各种Aware
,组装对应的属性,代码如下(ApplicationContextAwareProcessor#invokeAwareInterfaces
)private void invokeAwareInterfaces(Object bean) { //invoke各种Aware,组装对应的属性 if (bean instanceof EnvironmentAware) { ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment()); } if (bean instanceof EmbeddedValueResolverAware) { ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(this.embeddedValueResolver); } if (bean instanceof ResourceLoaderAware) { ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext); } if (bean instanceof ApplicationEventPublisherAware) { ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext); } if (bean instanceof MessageSourceAware) { ((MessageSourceAware) bean).setMessageSource(this.applicationContext); } if (bean instanceof ApplicationContextAware) { ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext); } }
-
设置几个忽略自动装配的接口,这些接口会在执行
ApplicationContextAwareProcessor
时自动装配执行//设置几个忽略自动装配的接口 //这些接口会在执行ApplicationContextAwareProcessor时自动装配执行 beanFactory.ignoreDependencyInterface(EnvironmentAware.class); beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class); beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class); beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class); beanFactory.ignoreDependencyInterface(MessageSourceAware.class); beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
-
设置几个自动装配的接口,一般检测到指定类型的属性,就会自动装配上去
//设置几个自动装配的接口 //一般检测到指定类型的属性,就会自动装配上去 beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory); beanFactory.registerResolvableDependency(ResourceLoader.class, this); beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this); beanFactory.registerResolvableDependency(ApplicationContext.class, this);
-
增加对
AspectJ
的支持 -
添加默认的系统环境
bean
4、子类覆盖方法做额外的处理
默认空实现,子类可以扩展做一些自定义的处理
5、激活各种BeanFactory
处理器
BeanFactoryPostProcessor
接口可以在实例化任何bean之前获取配置信息,从而可以正确解析bean描述文件中的变量引用
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
核心逻辑在第一行代码
//PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors方法
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
//记录已经触发的BeanDefinitionRegistryPostProcessors
Set<String> processedBeans = new HashSet<>();
//对于BeanFactoryPostProcessor的处理分为两种情况
//(1)对于BeanDefinitionRegistry类型的特殊处理
//(2)对于普通的BeanFactoryPostProcessor处理
//对BeanDefinitionRegistry类型的处理
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
//记录BeanFactoryPostProcessor类型的处理器
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
//记录BeanDefinitionRegistryPostProcessor类型的处理器
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//对于BeanDefinitionRegistryPostProcessor类型,需要先调用postProcessBeanDefinitionRegistry方法
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
//常规的BeanFactoryPostProcessor
else {
regularPostProcessors.add(postProcessor);
}
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// Separate between BeanDefinitionRegistryPostProcessors that implement
// PriorityOrdered, Ordered, and the rest.
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 获取配置文件中配置的且实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor
// 填充到currentRegistryProcessors
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//添加到registryProcessors中
registryProcessors.addAll(currentRegistryProcessors);
//invoke所有实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 获取配置文件中配置的且实现Ordered接口的BeanDefinitionRegistryPostProcessor
// 填充到currentRegistryProcessors
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);
}
}
//排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//添加到registryProcessors中
registryProcessors.addAll(currentRegistryProcessors);
//invoke所有实现Ordered接口的BeanDefinitionRegistryPostProcessor
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//获取配置文件中配置的剩余的BeanDefinitionRegistryPostProcessor(即未实现任何排序接口)
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;
}
}
//排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
//添加到registryProcessors中
registryProcessors.addAll(currentRegistryProcessors);
//invoke剩余的BeanDefinitionRegistryPostProcessor(即未实现任何排序接口)
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
//上面的代码只是触发BeanDefinitionRegistryPostProcessor类型中的postProcessBeanDefinitionRegistry方法,
//现在需要正式调用postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
//普通的beanFactory处理
else {
// Invoke factory processors registered with the context instance.
//对应非BeanDefinitionRegistry类型的beanFactory,直接调用postProcessBeanFactory方法
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
//获取配置文件里面的所有BeanFactoryPostProcessor类型的实例
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
//存放实现PriorityOrdered接口的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
//存放实现Ordered接口的BeanFactoryPostProcessor
List<String> orderedPostProcessorNames = new ArrayList<>();
//存放剩余的BeanFactoryPostProcessor
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
//已经执行过了的BeanFactoryPostProcessor执行跳过
if (processedBeans.contains(ppName)) {
// skip - already processed in first phase above
}
//实现了PriorityOrdered接口添加到priorityOrderedPostProcessors
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
}
//实现了Ordered接口添加到priorityOrderedPostProcessors
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
//剩余的(未实现任何排序接口)添加到priorityOrderedPostProcessors
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
//首选对实现PriorityOrdered接口的PostProcessor排序
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
//触发
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
//其次对实现Ordered接口的PostProcessor排序并触发
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
//最后对剩余的BeanFactoryPostProcessor进行触发
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String postProcessorName : nonOrderedPostProcessorNames) {
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
//清理缓存
beanFactory.clearMetadataCache();
}
上述代码看起来很多,但是实际上逻辑很简单,对于BeanFactoryPostProcessor
的处理分为两种情况
-
对于
BeanDefinitionRegistry
类型的特殊- 需要先对所有
BeanDefinitionRegistryPostProcessor
类型进行postProcessBeanDefinitionRegistry
方法触发,再触发BeanFactoryPostProcessor
的postProcessBeanFactory
方法
- 需要先对所有
-
非
BeanDefinitionRegistry
类型只需要触发
BeanFactoryPostProcessor
的postProcessBeanFactory
方法
在触发BeanDefinitionRegistryPostProcessor
和BeanFactoryPostProcessor
时,优选触发实现PriorityOrdered
类型,其次为Ordered
,剩余的最后触发。其中PriorityOrdered
和Ordered
内部根据配置的数字进行排序触发
6、注册BeanPostProcessor
这里只是注册,真正的调用在bean实例化的时候
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}
继续查看源码
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
//获取所有的BeanPostProcessor的beanName
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
// Register BeanPostProcessorChecker that logs an info message when
// a bean is created during BeanPostProcessor instantiation, i.e. when
// a bean is not eligible for getting processed by all BeanPostProcessors.
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
//存放实现priorityOrdered接口的BeanPostProcessor
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
//存放MergedBeanDefinitionPostProcessor
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
//存放实现Ordered接口的BeanPostProcessor
List<String> orderedPostProcessorNames = new ArrayList<>();
//存放无序的BeanPostProcessor
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
//如果是实现了PriorityOrdered接口,则加入到priorityOrderedPostProcessors集合中
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
//如果是MergedBeanDefinitionPostProcessor类型,则继续放入internalPostProcessors集合中
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
//如果是实现了Ordered接口,则加入到orderedPostProcessorNames集合中
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
//无任何排序规则,则加入到nonOrderedPostProcessorNames集合中
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, register the BeanPostProcessors that implement PriorityOrdered.
//第一步:注册所有实现PriorityOrdered接口的BeanPostProcessor
//先排序
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
//后注册
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
//第二步:注册所有实现Ordered接口的BeanPostProcessor
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
//如果是MergedBeanDefinitionPostProcessor类型,则继续放入internalPostProcessors集合中
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
//排序
sortPostProcessors(orderedPostProcessors, beanFactory);
//注册
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// Now, register all regular BeanPostProcessors.
//第三步:注册所有无序接口的BeanPostProcessor
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
//如果是MergedBeanDefinitionPostProcessor类型,则继续放入internalPostProcessors集合中
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
//注册
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// Finally, re-register all internal BeanPostProcessors.
//最后:注册所有MergedBeanDefinitionPostProcessor类型的BeanPostProcessor
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// Re-register post-processor for detecting inner beans as ApplicationListeners,
// moving it to the end of the processor chain (for picking up proxies etc).
//添加ApplicationListener探测器
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
逻辑与注册BeanFactoryPostProcessors
很类型,不过这里仅仅是注册,并不触发。且注册的先后顺序为
PriorityOrdered
–>Ordered
–>无序–>MergedBeanDefinitionPostProcessor
,如果既实现了排序接口,又实现了MergedBeanDefinitionPostProcessor
接口,则会当做MergedBeanDefinitionPostProcessor
来处理
7、为上下文初始化Message源(国际化处理)
即国际化处理
protected void initMessageSource() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
// Make MessageSource aware of parent MessageSource.
if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
if (hms.getParentMessageSource() == null) {
// Only set parent context as parent MessageSource if no parent MessageSource
// registered already.
hms.setParentMessageSource(getInternalParentMessageSource());
}
}
if (logger.isTraceEnabled()) {
logger.trace("Using MessageSource [" + this.messageSource + "]");
}
}
else {
// Use empty MessageSource to be able to accept getMessage calls.
DelegatingMessageSource dms = new DelegatingMessageSource();
dms.setParentMessageSource(getInternalParentMessageSource());
this.messageSource = dms;
beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
if (logger.isTraceEnabled()) {
logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
}
}
}
逻辑暂时略过…
8、初始化应用消息广播器
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//如果用户自定义了事件广播器,那么使用用户自定义的事件广播器
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
this.applicationEventMulticaster =
beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
if (logger.isTraceEnabled()) {
logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
}
}
//如果没有定义,则使用默认的SimpleApplicationEventMulticaster
else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
if (logger.isTraceEnabled()) {
logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
"[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
}
}
}
9、留给子类来初始化其它的Bean
默认空实现,子类可以用来初始化其他bean
10、在所有注册的bean中查找Listener bean
,并注册到消息广播器中
protected void registerListeners() {
// Register statically specified listeners first.
//硬编码方法注册的监听器
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let post-processors apply to them!
//配置文件注册的监听器处理
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// Publish early application events now that we finally have a multicaster...
//触发早期的时间监听器
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
主要将硬编码和配置文件里面的监听器注册到容器中
11、初始化剩下的单实例(非懒加载的)
相比于XmlBeanFactory
,ApplicationContext
在启动时就将所有注册的bean加载到容器中
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// Initialize conversion service for this context.
//初始化一些转换器
if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
beanFactory.setConversionService(
beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
}
// Register a default embedded value resolver if no bean post-processor
// (such as a PropertyPlaceholderConfigurer bean) registered any before:
// at this point, primarily for resolution in annotation attribute values.
//如果没有任何bean post-processor,会默认注入属性解析器
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
}
// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
//初始化LoadTimeWeaverAware类型
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// Stop using the temporary ClassLoader for type matching.
//停止使用临时ClassLoader进行类型匹配
beanFactory.setTempClassLoader(null);
// Allow for caching all bean definition metadata, not expecting further changes.
//冻结所有的bean定义,即bean定义将不被修改或者进行任何一步的处理
beanFactory.freezeConfiguration();
// Instantiate all remaining (non-lazy-init) singletons.
// 实例化所有剩余的(非延迟初始化)单例
//ApplicationContext默认就是启动时将所有单例bean提前进行实例化
beanFactory.preInstantiateSingletons();
}
这里最重要的是最后一步:实例化所有剩余的(非延迟初始化)单例
public void preInstantiateSingletons() throws BeansException {
if (logger.isTraceEnabled()) {
logger.trace("Pre-instantiating singletons in " + this);
}
// Iterate over a copy to allow for init methods which in turn register new bean definitions.
// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans...
//触发所有非惰性单例bean的初始化
for (String beanName : beanNames) {
//获取bean配置信息
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
//只加载单例非懒加载的非抽象类
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
//对应FactoryBean类型的实例的加载
if (isFactoryBean(beanName)) {
Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
if (bean instanceof FactoryBean) {
final FactoryBean<?> factory = (FactoryBean<?>) bean;
boolean isEagerInit;
if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
isEagerInit = AccessController.doPrivileged((PrivilegedAction<Boolean>)
((SmartFactoryBean<?>) factory)::isEagerInit,
getAccessControlContext());
}
else {
isEagerInit = (factory instanceof SmartFactoryBean &&
((SmartFactoryBean<?>) factory).isEagerInit());
}
if (isEagerInit) {
getBean(beanName);
}
}
}
//普通bean的加载
else {
getBean(beanName);
}
}
}
// Trigger post-initialization callback for all applicable beans...
//触发所有bean的初始化后回调
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
if (singletonInstance instanceof SmartInitializingSingleton) {
final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
smartSingleton.afterSingletonsInstantiated();
return null;
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
}
}
}
这里分为两大步骤
- 首先就是加载所有非惰性单例bean
- 其次是触发
SmartInitializingSingleton
类型bean的afterSingletonsInstantiated
方法,即触发bean的初始化后回调
加载bean的逻辑就是getBean
方法,这里不再赘述。
12、完成刷新过程的后续处理
protected void finishRefresh() {
// Clear context-level resource caches (such as ASM metadata from scanning).
// 清除上下文级别的资源缓存
clearResourceCaches();
// Initialize lifecycle processor for this context.
// 为此上下文初始化生命周期处理器
initLifecycleProcessor();
// Propagate refresh to lifecycle processor first.
//触发所有生命周期处理器的onRefresh方法
getLifecycleProcessor().onRefresh();
// Publish the final event.
//发布上下文刷新事件
publishEvent(new ContextRefreshedEvent(this));
// Participate in LiveBeansView MBean, if active.
LiveBeansView.registerApplicationContext(this);
}
主要做了以下几件事
-
清除上下文级别的资源缓存
-
为此上下文初始化生命周期处理器
LifecycleProcessor
protected void initLifecycleProcessor() { ConfigurableListableBeanFactory beanFactory = getBeanFactory(); //如果本地存在lifecycleProcessor,则获取本地lifecycleProcessor if (beanFactory.containsLocalBean(LIFECYCLE_PROCESSOR_BEAN_NAME)) { this.lifecycleProcessor = beanFactory.getBean(LIFECYCLE_PROCESSOR_BEAN_NAME, LifecycleProcessor.class); if (logger.isTraceEnabled()) { logger.trace("Using LifecycleProcessor [" + this.lifecycleProcessor + "]"); } } //否则使用默认的DefaultLifecycleProcessor else { DefaultLifecycleProcessor defaultProcessor = new DefaultLifecycleProcessor(); defaultProcessor.setBeanFactory(beanFactory); this.lifecycleProcessor = defaultProcessor; beanFactory.registerSingleton(LIFECYCLE_PROCESSOR_BEAN_NAME, this.lifecycleProcessor); if (logger.isTraceEnabled()) { logger.trace("No '" + LIFECYCLE_PROCESSOR_BEAN_NAME + "' bean, using " + "[" + this.lifecycleProcessor.getClass().getSimpleName() + "]"); } } }
-
触发生命周期处理器
LifecycleProcessor
@Override public void onRefresh() { startBeans(true); this.running = true; }
这里是调用方法
startBeans
private void startBeans(boolean autoStartupOnly) { //获取容器中所有的Lifecycle Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans(); Map<Integer, LifecycleGroup> phases = new HashMap<>(); //根据phase将这些Lifecycle进行分组 lifecycleBeans.forEach((beanName, bean) -> { if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) { int phase = getPhase(bean); LifecycleGroup group = phases.get(phase); if (group == null) { group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly); phases.put(phase, group); } group.add(beanName, bean); } }); if (!phases.isEmpty()) { List<Integer> keys = new ArrayList<>(phases.keySet()); //排序 Collections.sort(keys); //按照排序进行触发 for (Integer key : keys) { phases.get(key).start(); } } }
按照分组顺序进行逐个触发
-
发布上下文刷新事件
13、上述过程出现异常后的处理
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
//销毁已创建的单例
destroyBeans();
// Reset 'active' flag.
//重置active标志
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
-
首先销毁所有的单例bean
protected void destroyBeans() { getBeanFactory().destroySingletons(); }
-
重置active标志
protected void cancelRefresh(BeansException ex) { this.active.set(false); }
14、清除内置缓存
protected void resetCommonCaches() {
//清除反射使用到的方法和字段缓存
ReflectionUtils.clearCache();
//清除注解缓存
AnnotationUtils.clearCache();
//清除ResolvableType缓存
ResolvableType.clearCache();
//清除ClassLoader缓存
CachedIntrospectionResults.clearClassLoader(getClassLoader());
}
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