13.【Spring源码分析】13-DispatcherServlet中WebApplicationContext启动过程
13.【Spring源码分析】13-DispatcherServlet中WebApplicationContext启动过程
DispatcherServlet中WebApplicationContext的启动在父类FrameworkServlet的configureAndRefreshWebApplicationContext()方法中，其中WebApplicationContext的具体子类是AnnotationConfigWebApplicationContext。下图为ApplicationContext的继承结构。
protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac) {
if (ObjectUtils.identityToString(wac).equals(wac.getId())) {
// The application context id is still set to its original default value
// -> assign a more useful id based on available information
if (this.contextId != null) {
wac.setId(this.contextId);
}
else {
// Generate default id...
wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
ObjectUtils.getDisplayString(getServletContext().getContextPath()) + '/' + getServletName());
}
}
wac.setServletContext(getServletContext());
wac.setServletConfig(getServletConfig());
wac.setNamespace(getNamespace());
wac.addApplicationListener(new SourceFilteringListener(wac, new ContextRefreshListener()));
// The wac environment's #initPropertySources will be called in any case when the context
// is refreshed; do it eagerly here to ensure servlet property sources are in place for
// use in any post-processing or initialization that occurs below prior to #refresh
ConfigurableEnvironment env = wac.getEnvironment();
if (env instanceof ConfigurableWebEnvironment) {
((ConfigurableWebEnvironment) env).initPropertySources(getServletContext(), getServletConfig());
}
postProcessWebApplicationContext(wac);
applyInitializers(wac);
wac.refresh();
}ContextRefreshListener是FrameworkServlet的一个内部类，调用本实例(也就是DispatcherServlet)的onApplicationEvent()方法。
private class ContextRefreshListener implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
FrameworkServlet.this.onApplicationEvent(event);
}
}public void onApplicationEvent(ContextRefreshedEvent event) {
this.refreshEventReceived = true;
onRefresh(event.getApplicationContext());
}@Override
protected void onRefresh(ApplicationContext context) {
initStrategies(context);
}initStrategies()在Spring MVC中在分析，这里知道是在什么地方注册的回调即可(finishRefresh()中会发布ContextRefreshedEvent事件)。
postProcessWebApplicationContext()为一个空实现，子类可以覆盖此方法，用于在ConfigurableWebApplicationContext刷新前对它进行一些操作。
applyInitializers()方法用于执行注册到contextInitializers中的ApplicationContextInitializer对象，执行顺序就是 AnnotationAwareOrderComparator的排序规则，优先级如下，其中order值越小代表优先级越高。
实现PriorityOrdered接口>实现Ordered接口>被标记@Order或@Priorityprotected void applyInitializers(ConfigurableApplicationContext wac) {
String globalClassNames = getServletContext().getInitParameter(ContextLoader.GLOBAL_INITIALIZER_CLASSES_PARAM);
if (globalClassNames != null) {
for (String className : StringUtils.tokenizeToStringArray(globalClassNames, INIT_PARAM_DELIMITERS)) {
this.contextInitializers.add(loadInitializer(className, wac));
}
}
if (this.contextInitializerClasses != null) {
for (String className : StringUtils.tokenizeToStringArray(this.contextInitializerClasses, INIT_PARAM_DELIMITERS)) {
this.contextInitializers.add(loadInitializer(className, wac));
}
}
AnnotationAwareOrderComparator.sort(this.contextInitializers);
for (ApplicationContextInitializer<ConfigurableApplicationContext> initializer : this.contextInitializers) {
initializer.initialize(wac);
}
}Spring核心框架中没有提供具体的ApplicationContextInitializer实现类，而Spring Boot提供了一系列实现如下，介绍《SpringApplication运行阶段》时在详细介绍。
refresh()是ApplicationContext启动的入口方法，作为一个模板方法被定义在了AbstractApplicationContext中，由子类决定具体方法的行为。
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
finishRefresh();
}
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.
destroyBeans();
// Reset 'active' flag.
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...
resetCommonCaches();
}
}
}1、prepareRefresh()在启动容器前做一些准备工作。
protected void prepareRefresh() {
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isInfoEnabled()) {
logger.info("Refreshing " + this);
}
// 在上下文环境中初始化任何占位符属性源
initPropertySources();//这步在FrameworkServlet中已经做过，对于WebApplicationContext
// 验证标记为必需的所有属性是否可解析请参阅
// ConfigurablePropertyResolver＃setRequiredProperties
getEnvironment().validateRequiredProperties();
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
this.earlyApplicationEvents = new LinkedHashSet<ApplicationEvent>();
}2、obtainFreshBeanFactory()创建一个BeanFactory，一般是DefaultListableBeanFactory。
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
refreshBeanFactory();
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (logger.isDebugEnabled()) {
logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
}
return beanFactory;
}@Override
protected final void refreshBeanFactory() throws BeansException {
if (hasBeanFactory()) {
destroyBeans();
closeBeanFactory();
}
try {
DefaultListableBeanFactory beanFactory = createBeanFactory();
beanFactory.setSerializationId(getId());
customizeBeanFactory(beanFactory);
// 重要方法，加载定义的bean
loadBeanDefinitions(beanFactory);
synchronized (this.beanFactoryMonitor) {
this.beanFactory = beanFactory;
}
}
catch (IOException ex) {
throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
}
}protected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) {
if (this.allowBeanDefinitionOverriding != null) {
// 允许bean重复定义 默认false
beanFactory.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
}
if (this.allowCircularReferences != null) {
// 允许bean循环引用 默认true
beanFactory.setAllowCircularReferences(this.allowCircularReferences);
}
}2.1、loadBeanDefinitions()方法用来加载并解析Bean为BeanDefinition。
下面是AnnotationConfigWebApplicationContext的具体实现。
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) {
// ClassPathBeanDefinitionScanner的替代类，用于解析基于注解的bean类的编程式注册
AnnotatedBeanDefinitionReader reader = getAnnotatedBeanDefinitionReader(beanFactory);
// 扫描包中的候选者类，前者直接解析类，后者扫描包中类
ClassPathBeanDefinitionScanner scanner = getClassPathBeanDefinitionScanner(beanFactory);
BeanNameGenerator beanNameGenerator = getBeanNameGenerator();
if (beanNameGenerator != null) {
reader.setBeanNameGenerator(beanNameGenerator);
scanner.setBeanNameGenerator(beanNameGenerator);
// 将取名器也注册为一个单例bean 默认null
beanFactory.registerSingleton(AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR, beanNameGenerator);
}
// 用于解析scope 定义的bean的策略接口默认为null
ScopeMetadataResolver scopeMetadataResolver = getScopeMetadataResolver();
if (scopeMetadataResolver != null) {
reader.setScopeMetadataResolver(scopeMetadataResolver);
scanner.setScopeMetadataResolver(scopeMetadataResolver);
}
if (!this.annotatedClasses.isEmpty()) {
if (logger.isInfoEnabled()) {
logger.info("Registering annotated classes: [" +
StringUtils.collectionToCommaDelimitedString(this.annotatedClasses) + "]");
}
// 注册一个或多个要处理的带注解@Configuration的类。
reader.register(this.annotatedClasses.toArray(new Class<?>[this.annotatedClasses.size()]));
}
if (!this.basePackages.isEmpty()) {
if (logger.isInfoEnabled()) {
logger.info("Scanning base packages: [" +
StringUtils.collectionToCommaDelimitedString(this.basePackages) + "]");
}
// 在指定的基础包中执行扫描。
scanner.scan(this.basePackages.toArray(new String[this.basePackages.size()]));
}
// 在AnnotationConfigWebApplicationContext中，configLocations代表@Configuration类名或要扫描的包名
String[] configLocations = getConfigLocations();
if (configLocations != null) {
for (String configLocation : configLocations) {
try {
Class<?> clazz = getClassLoader().loadClass(configLocation);
if (logger.isInfoEnabled()) {
logger.info("Successfully resolved class for [" + configLocation + "]");
}
reader.register(clazz);
}
catch (ClassNotFoundException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Could not load class for config location [" + configLocation +
"] - trying package scan. " + ex);
}
int count = scanner.scan(configLocation);
if (logger.isInfoEnabled()) {
if (count == 0) {
logger.info("No annotated classes found for specified class/package [" + configLocation + "]");
}
else {
logger.info("Found " + count + " annotated classes in package [" + configLocation + "]");
}
}
}
}
}
}AnnotatedBeanDefinitionReader和ClassPathBeanDefinitionScanner分别用来解析指定的Class和指定包下的Class为BeanDefinition。
protected AnnotatedBeanDefinitionReader getAnnotatedBeanDefinitionReader(DefaultListableBeanFactory beanFactory) {
return new AnnotatedBeanDefinitionReader(beanFactory, getEnvironment());
}
protected ClassPathBeanDefinitionScanner getClassPathBeanDefinitionScanner(DefaultListableBeanFactory beanFactory) {
return new ClassPathBeanDefinitionScanner(beanFactory, true, getEnvironment());
}2.1.1、AnnotatedBeanDefinitionReader
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
Assert.notNull(environment, "Environment must not be null");
this.registry = registry;
this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}ConditionEvaluator是Spring内部使用的类，用来解析@Conditional注解。
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry)为BeanFactory进行一些配置，主要是注册一些框架级别的BeanFactoryPostProcessor，这些BeanFactoryPostProcessor都非常重要，下面给出这些BeanFactoryPostProcessor源码分析的连接地址。
《【Spring源码分析】AutowiredAnnotationBeanPostProcessor》、《【Spring源码分析】RequiredAnnotationBeanPostProcessor》、《【Spring源码分析】CommonAnnotationBeanPostProcessor》、《【Spring源码分析】ConfigurationClassPostProcessor》、《【Spring源码分析】ApplicationEvent事件机制》
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
BeanDefinitionRegistry registry, Object source) {
// 取得ApplicationContext持有的beanFactory，而不是ApplicationContext本身
DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
if (beanFactory != null) {
if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
}
if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
// 将默认的SimpleAutowireCandidateResolver替换成支持@Qualifier、@Value、@Lazy注解的ContextAnnotationAutowireCandidateResolver
beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
}
}
// 下面是注册框架级别的一些用于注解的基础组件
Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<BeanDefinitionHolder>(4);
if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
}
if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
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));
}
// 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));
}
// 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));
}
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));
}
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;
}之后会调用registerBean()方法从给定的Class上面的注解上推导出BeanDefinition。
public void registerBean(Class<?> annotatedClass, String name, Class<? extends Annotation>... qualifiers) {
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
// 不满足@Conditional注解value指定的实现Condition接口的实现类则跳过
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
//默认使用AnnotationScopeMetadataResolver从@Scope得到scopeName(默认singleton)和scopedProxyMode(默认ScopedProxyMode.NO)
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
abd.setScope(scopeMetadata.getScopeName());
// 默认使用AnnotationBeanNameGenerator根据@Component(或继承他的注解)、@ManagedBean、@Named的value属性取名
// 如果均不存在这些注解则使用类名首字母小写作为bean name
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
//根据注解@Lazy,@Primary,@DependsOn,@Role,@Description设置BeanDefinition相应的属性
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
if (qualifiers != null) {
for (Class<? extends Annotation> qualifier : qualifiers) {
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
else {
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
//如果是ScopedProxyMode.TARGET_CLASS，使用ScopedProxyCreator.createScopedProxy()新建一个BeanDefinition替换原有的
//新的beanClass为ScopedProxyFactoryBean，是原始bean的代理对象，而原始bean重命名为scopedTarget.beanname
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}2.1.2、ClassPathBeanDefinitionScanner
这部分内容移至《Spring源码分析-ClassPathBeanDefinitionScanner》。
3、prepareBeanFactory()为BeanFactory配置标准的上下文特征如post-processors。
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
//下面6种类型autowire不会自动装配，因为ApplicationContextAwareProcessor会自动set相应的对象
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()));
}
// Register default environment beans.
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
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());
}
}4、postProcessBeanFactory()由子类AbstractRefreshableWebApplicationContext覆盖，添加与servletContext相关的bean。
@Override
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext, this.servletConfig));
beanFactory.ignoreDependencyInterface(ServletContextAware.class);
beanFactory.ignoreDependencyInterface(ServletConfigAware.class);
//注册针对web环境的scope ("request", "session", "globalSession", "application")
//具体设计实现参考https://blog.csdn.net/shenchaohao12321/article/details/86656236
WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
//注册ServletContext环境相关的单例
WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext, this.servletConfig);
}
public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory, ServletContext sc) {
beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());
beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope(false));
beanFactory.registerScope(WebApplicationContext.SCOPE_GLOBAL_SESSION, new SessionScope(true));
if (sc != null) {
ServletContextScope appScope = new ServletContextScope(sc);
beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope);
// Register as ServletContext attribute, for ContextCleanupListener to detect it.
sc.setAttribute(ServletContextScope.class.getName(), appScope);
}
beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory());
beanFactory.registerResolvableDependency(ServletResponse.class, new ResponseObjectFactory());
beanFactory.registerResolvableDependency(HttpSession.class, new SessionObjectFactory());
beanFactory.registerResolvableDependency(WebRequest.class, new WebRequestObjectFactory());
if (jsfPresent) {
FacesDependencyRegistrar.registerFacesDependencies(beanFactory);
}
}
//使用WebApplicationContext使用的给定BeanFactory注册特定于Web的环境bean（"contextParameters"，"contextAttributes"）。
public static void registerEnvironmentBeans(
ConfigurableListableBeanFactory bf, ServletContext servletContext, ServletConfig servletConfig) {
if (servletContext != null && !bf.containsBean(WebApplicationContext.SERVLET_CONTEXT_BEAN_NAME)) {
bf.registerSingleton(WebApplicationContext.SERVLET_CONTEXT_BEAN_NAME, servletContext);
}
if (servletConfig != null && !bf.containsBean(ConfigurableWebApplicationContext.SERVLET_CONFIG_BEAN_NAME)) {
bf.registerSingleton(ConfigurableWebApplicationContext.SERVLET_CONFIG_BEAN_NAME, servletConfig);
}
if (!bf.containsBean(WebApplicationContext.CONTEXT_PARAMETERS_BEAN_NAME)) {
Map<String, String> parameterMap = new HashMap<String, String>();
if (servletContext != null) {
Enumeration<?> paramNameEnum = servletContext.getInitParameterNames();
while (paramNameEnum.hasMoreElements()) {
String paramName = (String) paramNameEnum.nextElement();
parameterMap.put(paramName, servletContext.getInitParameter(paramName));
}
}
if (servletConfig != null) {
Enumeration<?> paramNameEnum = servletConfig.getInitParameterNames();
while (paramNameEnum.hasMoreElements()) {
String paramName = (String) paramNameEnum.nextElement();
parameterMap.put(paramName, servletConfig.getInitParameter(paramName));
}
}
bf.registerSingleton(WebApplicationContext.CONTEXT_PARAMETERS_BEAN_NAME,
Collections.unmodifiableMap(parameterMap));
}
if (!bf.containsBean(WebApplicationContext.CONTEXT_ATTRIBUTES_BEAN_NAME)) {
Map<String, Object> attributeMap = new HashMap<String, Object>();
if (servletContext != null) {
Enumeration<?> attrNameEnum = servletContext.getAttributeNames();
while (attrNameEnum.hasMoreElements()) {
String attrName = (String) attrNameEnum.nextElement();
attributeMap.put(attrName, servletContext.getAttribute(attrName));
}
}
bf.registerSingleton(WebApplicationContext.CONTEXT_ATTRIBUTES_BEAN_NAME,
Collections.unmodifiableMap(attributeMap));
}
}5、invokeBeanFactoryPostProcessors()方法用来执行已经注册过的 BeanFactoryPostProcessor，许多核心注解处理器就在这个地方生效的，以后会单独讲解这些核心BeanFactoryPostProcessor。
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//注解配置核心类ConfigurationClassPostProcessor生效的地方
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()));
}
}下面是PostProcessorRegistrationDelegate的代码，逐句分析一下。
class PostProcessorRegistrationDelegate {
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
//用来保存已从bean factory取出以bean定义方式注册的BeanFactoryPostProcessor的bean name
Set<String> processedBeans = new HashSet<>();
//首先调用BeanDefinitionRegistryPostProcessors，如果有的话。
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
//保存一般的BeanFactoryPostProcessor而非BeanDefinitionRegistryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<>();
//保存特殊的BeanFactoryPostProcessor子类BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<>();
//优先处理已通过addBeanFactoryPostProcessor()方法添加好的BeanFactoryPostProcessor
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//如果是BeanDefinitionRegistryPostProcessor直接调用其postProcessBeanDefinitionRegistry()方法并保存它
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
//普通BeanFactoryPostProcessor先不执行，保存下来后面同一执行
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.
//从bean定义方式中找出实现了接口PriorityOrdered的BeanDefinitionRegistryPostProcessor的bean实例，放入容器currentRegistryProcessors中
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);
}
}
//将bean定义形式的BeanDefinitionRegistryPostProcessor实例按已设置的dependencyComparator(AnnotationAwareOrderComparator.INSTANCE)排序，排序规则前面讲过
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
//按照排序好的BeanDefinitionRegistryPostProcessor对象依次调用postProcessBeanDefinitionRegistry()方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
//从bean定义方式中找出实现了接口Ordered的BeanDefinitionRegistryPostProcessor的bean实例，并且保证不能重复处理同一个对象
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);
//到此为止，Spring框架内置的与我们手动添加(包括addBeanFactoryPostProcessor和BeanDefinition形式)的BeanDefinitionRegistryPostProcessor已执行完毕
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 由于registryProcessors中的BeanDefinitionRegistryPostProcessor.postProcessBeanDefinitionRegistry()方法可能会动态的添加一些bean定义和BeanFactoryPostProcessor
// 所以需要不断地从beanFactory中取出registryProcessors未保存的BeanDefinitionRegistryPostProcessor实例调用postProcessBeanDefinitionRegistry()方法
// 直到beanFactory不再有新的BeanDefinitionRegistryPostProcessor实例出现
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.
// postProcessBeanDefinitionRegistry()方法全都执行完后，就可以执行BeanFactoryPostProcessor中的postProcessBeanFactory()方法了
// BeanDefinitionRegistryPostProcessor优先执行于BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// 最后处理bean定义的BeanFactoryPostProcessor，优先级为：实现PriorityOrdered接口的 > 实现Ordered接口的 > 其他
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();
}
}6、registerBeanPostProcessors()方法从bean factory中实例化BeanPostProcessor后注册。
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
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;
// 如果一个bean实例化的时候不是所有BeanPostProcessor都被注册，这时BeanPostProcessorChecker会打印info级别的日志:
// logger.info("Bean '" + beanName + "' of type [" + bean.getClass().getName() + "] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)")
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,Ordered, and the rest.
// 处理区分优先级与BeanFactoryPostProcessor一样
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
// 保存MergedBeanDefinitionPostProcessor实例并且最后注册
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, register the BeanPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// Now, register all regular BeanPostProcessors.
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// Finally, re-register all internal BeanPostProcessors.
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).
// ApplicationListenerDetector会将单例bean是ApplicationListener的加入applicationContext中
// applicationContext.addApplicationListener((ApplicationListener<?>) bean)
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}7、initMessageSource()方法为容器中注册一个名为messageSource的 DelegatingMessageSource的bean用于i18n。
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.isDebugEnabled()) {
logger.debug("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.isDebugEnabled()) {
logger.debug("Unable to locate MessageSource with name '" + MESSAGE_SOURCE_BEAN_NAME +
"': using default [" + this.messageSource + "]");
}
}
}8、initApplicationEventMulticaster()方法注册applicationEventMulticaster
初始化ApplicationEventMulticaster。 如果在上下文中没有定义，则使用SimpleApplicationEventMulticaster。
关于ApplicationEventMulticaster的实现原理请参考《【Spring源码分析】ApplicationEvent事件机制》。
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
this.applicationEventMulticaster =
beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
if (logger.isDebugEnabled()) {
logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
}
}
else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
if (logger.isDebugEnabled()) {
logger.debug("Unable to locate ApplicationEventMulticaster with name '" +
APPLICATION_EVENT_MULTICASTER_BEAN_NAME +
"': using default [" + this.applicationEventMulticaster + "]");
}
}
}9、onRefresh()方法默认在AbstractRefreshableWebApplicationContext中创建一个名为themeSource变量的ResourceBundleThemeSource。
public static ThemeSource initThemeSource(ApplicationContext context) {
if (context.containsLocalBean(THEME_SOURCE_BEAN_NAME)) {
ThemeSource themeSource = context.getBean(THEME_SOURCE_BEAN_NAME, ThemeSource.class);
// Make ThemeSource aware of parent ThemeSource.
if (context.getParent() instanceof ThemeSource && themeSource instanceof HierarchicalThemeSource) {
HierarchicalThemeSource hts = (HierarchicalThemeSource) themeSource;
if (hts.getParentThemeSource() == null) {
// Only set parent context as parent ThemeSource if no parent ThemeSource
// registered already.
hts.setParentThemeSource((ThemeSource) context.getParent());
}
}
if (logger.isDebugEnabled()) {
logger.debug("Using ThemeSource [" + themeSource + "]");
}
return themeSource;
}
else {
// Use default ThemeSource to be able to accept getTheme calls, either
// delegating to parent context's default or to local ResourceBundleThemeSource.
HierarchicalThemeSource themeSource = null;
if (context.getParent() instanceof ThemeSource) {
themeSource = new DelegatingThemeSource();
themeSource.setParentThemeSource((ThemeSource) context.getParent());
}
else {
themeSource = new ResourceBundleThemeSource();
}
if (logger.isDebugEnabled()) {
logger.debug("Unable to locate ThemeSource with name '" + THEME_SOURCE_BEAN_NAME +
"': using default [" + themeSource + "]");
}
return themeSource;
}
}10、registerListeners()方法将容器中的所有ApplicationListener添加到ApplicationEventMulticaster中以便所有ApplicationListener可以监听到消息。
protected void registerListeners() {
// Register statically specified listeners first.
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!
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...
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}11、finishBeanFactoryInitialization()方法主要是提前实例化单例对象。
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// Initialize conversion service for this context.
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.
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(new StringValueResolver() {
@Override
public String resolveStringValue(String strVal) {
return getEnvironment().resolvePlaceholders(strVal);
}
});
}
// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// Stop using the temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(null);
// Allow for caching all bean definition metadata, not expecting further changes.
beanFactory.freezeConfiguration();
// Instantiate all remaining (non-lazy-init) singletons.
beanFactory.preInstantiateSingletons();
}public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("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...
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
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);
}
}
}
else {
getBean(beanName);
}
}
}
// Trigger post-initialization callback for all applicable beans...
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();
}
}
}
}12、finishRefresh()注册LifecycleProcessor，发布ContextRefreshedEvent。
protected void finishRefresh() {
// 如果没有配置beanname是lifecycleProcessor则使用DefaultLifecycleProcessor
initLifecycleProcessor();
// 对于DefaultLifecycleProcessor调用其startBeans(true)方法，会中出容器中所有的Lifecycle调用它的start()方法
getLifecycleProcessor().onRefresh();
// 向监听器发送广播，容器启动事件
publishEvent(new ContextRefreshedEvent(this));
// 如果配置了MBeanServer，就完成在MBeanServer上的注册
LiveBeansView.registerApplicationContext(this);
}初始化LifecycleProcessor。如果在上下文中没有定义，则使用DefaultLifecycleProcessor。
protected void initLifecycleProcessor() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
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 + "]");
}
}
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() + "]");
}
}
}关于LifecycleProcessor请参考《【Spring源码分析】Spring容器生命周期回调接口------LifeCycle》。
来源：https://blog.csdn.net/shenchaohao12321/article/details/80649337