- 这一节的内容主要是探索spring的容器创建过程，这个过程非常的复杂，包含了容器的创建、bean的加载-创建-注册-初始化、以及其他组件的注册等等过程。但是好在spring对整个过程封装逻辑比较清晰，可以通过源码一步一步的解读。
1、准备阶段
- 为了能进行debug进行源码解读，需要创建一个简单的测试环境，然后对其中加载配置文件并创建容器那一行打一个断点。
//创建一个注解形式的配置类
@Configuration//标记这个类为注解类==配置文件
public class UserConfig {
@Bean
public User user() {
return new User();
}
}
//测试
public class Test {
public static void main(String[] args) {
//加载配置文件并创建容器
ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(UserConfig.class);
User user = (User) context.getBean("user");
System.out.println(user);
}
}
- 创建AnnotationConfigApplicationContext
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
//创建AnnotationConfigApplicationContextbin初始化相关信息类
this();
//注册多个注解Bean定义类
register(annotatedClasses);
//刷新容器
refresh();
}
二、this()方法
- 主要完成创建注解bean解析器和类路径bean定义扫描器的创建，并设置到容器中
//创建一个读取注解的Bean定义读取器，并将其设置到容器中
private final AnnotatedBeanDefinitionReader reader;
//创建一个扫描指定类路径中注解Bean定义的扫描器，并将其设置到容器中
private final ClassPathBeanDefinitionScanner scanner;
public AnnotationConfigApplicationContext() {
1..... this.reader = new AnnotatedBeanDefinitionReader(this);
2..... this.scanner = new ClassPathBeanDefinitionScanner(this);
}
(1)1所处的行最终会执行
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
Assert.notNull(environment, "Environment must not be null");
//interface for registries that hold bean definitions
this.registry = registry;
//Internal class used to evaluate {@link Conditional} annotations.
this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
(2)2所处的行最终会执行
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters, Environment environment) {
super(useDefaultFilters, environment);
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
// Determine ResourceLoader to use.
if (this.registry instanceof ResourceLoader) {
setResourceLoader((ResourceLoader) this.registry);
}
}
3、register(annotatedClasses)方法
- 主要利用AnnotatedBeanDefinitionReader对注解bean进行解析并进行注册
1、AnnotationConfigApplicationContext.register
public void register(Class<?>... annotatedClasses) {
Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified");
this.reader.register(annotatedClasses);
}
2、AnnotatedBeanDefinitionReader.register
public void register(Class<?>... annotatedClasses) {
for (Class<?> annotatedClass : annotatedClasses) {
registerBean(annotatedClass);
}
}
3、AnnotatedBeanDefinitionReader.registerBean
public void registerBean(Class<?> annotatedClass, String name,
@SuppressWarnings("unchecked") Class<? extends Annotation>... qualifiers) {
//该类继承GenericBeanDefinition并实现AnnotatedBeanDefinition，
//AnnotatedGenericBeanDefinition 描述了一个注解bean实例，它具有属性值，构造函数参数值。
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
//根据{@code @Conditional}注释确定是否应跳过某个项目
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
//ScopeMetadata 描述了一个Spring管理的bean，包括范围名称和范围的代理行为范围的特点。(也就是spring的作用域）
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
abd.setScope(scopeMetadata.getScopeName());
//获取传入注解配置类的bean
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
//处理该注解bean上的一些其他注解属性，比如@lazy，@Primary等注解
//有的话加入到AnnotatedGenericBeanDefinition 中
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
//@qualifiers注解
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拥有名称和别名的BeanDefinition的持有者。可以注册为内部bean的占位符。
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
//在BeanDefinitionRegistry中注册相应的获取的bean，definitionHolder.getBeanName()作为beanName
//definitionHolder.getBeanDefinition()作为value，如果有别名还要进行别名注册
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
四、refresh方法
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 1、prepareRefresh()刷新前的预处理.
prepareRefresh();
// 2、获取BeanFactory.
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
//3、BeanFactory的预准备工作（BeanFactory进行一些设置）.
prepareBeanFactory(beanFactory);
try {
// 4、BeanFactory准备工作完成后进行的后置处理工作
postProcessBeanFactory(beanFactory);
======================以上是BeanFactory的创建及预准备工作===============
// 5、执行BeanFactoryPostProcessor的方法
invokeBeanFactoryPostProcessors(beanFactory);
//6、注册BeanPostProcessor（Bean的后置处理器）
registerBeanPostProcessors(beanFactory);
// 7、初始化MessageSource组件（做国际化功能；消息绑定，消息解析）；
initMessageSource();
//8、初始化事件派发器；
initApplicationEventMulticaster();
// 9、在子容器（子类）初初始化特殊的bean
onRefresh();
// 10、给容器中将所有项目里面的ApplicationListener注册进来.
registerListeners();
// 11、初始化所有剩下的单实例bean；
finishBeanFactoryInitialization(beanFactory);
// 12、完成BeanFactory的初始化创建工作；IOC容器就创建完成；
finishRefresh();
}
1、prepareRefresh刷新前的预处理
- 完成容器刷新前的准备工作，设置其启动日期和活动标志以及执行属性源的任何初始化。
protected void prepareRefresh() {
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isInfoEnabled()) {
logger.info("Refreshing " + this);
}
//1、初始化一些属性设置（抽象方法，子类自定义个性化的属性设置方法）
initPropertySources();
//2、 检验属性的合法等
getEnvironment().validateRequiredProperties();
// 3、保存容器中的一些早期的事件
this.earlyApplicationEvents = new LinkedHashSet<ApplicationEvent>();
}
3、obtainFreshBeanFactory获取BeanFactory
GenericApplicationContext
//1、告诉子类刷新内部bean工厂
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
//(1)刷新【创建】BeanFactory,并设置序列id，其中this.beanFactory为
//DefaultListableBeanFactory,这个beanfactory创建过程是在上面介绍的this方法中执行的，
//因为AnnotatedBeanDefinitionReader继承GenericApplicationContext类
refreshBeanFactory();
//返回刚才DefaultListableBeanFactory对象
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (logger.isDebugEnabled()) {
logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
}
return beanFactory;
}
3、prepareBeanFactoryBeanFactory的预准备工作
//配置工厂的标准上下文特征，例如上下文的ClassLoader和后处理器
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 1、设置BeanFactory的类加载器、支持表达式解析器...
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
//2、 添加部分BeanPostProcessor【例如ApplicationContextAwareProcessor】
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
//3、设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx；
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
//4、注册可以解析的自动装配；我们能直接在任何组件中自动注入：BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// 5、添加编译时的AspectJ；
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()));
}
// 6、给BeanFactory中注册一些能用的组件：environment【ConfigurableEnvironment】、
//systemProperties【Map<String, Object>】、systemEnvironment【Map<String, Object>】
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完成后置处理工作
//子类通过重写这个方法来在BeanFactory创建并预准备完成以后做进一步的设置
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
}
5、执行BeanFactoryPostProcessor的方法
- 实例化并调用所有已注册的BeanFactoryPostProcessor bean，如果给定，则遵循显式顺序。必须在单例实例化之前调用
- BeanFactoryPostProcessor：BeanFactory的后置处理器。在BeanFactory标准初始化之后执行的
1、AbstractApplicationContext.invokeBeanFactoryPostProcessors
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//执行invokeBeanFactoryPostProcessors方法
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()));
}
}
2、PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<String>();
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
List<BeanDefinitionRegistryPostProcessor> registryPostProcessors =
new LinkedList<BeanDefinitionRegistryPostProcessor>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryPostProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryPostProcessor.postProcessBeanDefinitionRegistry(registry);
registryPostProcessors.add(registryPostProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
===============先执行BeanDefinitionRegistryPostProcessor接口============
//1、获取所有的实现该BeanDefinitionRegistryPostProcessor的名称
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//2、看先执行实现了PriorityOrdered优先级接口的BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(beanFactory, priorityOrderedPostProcessors);
registryPostProcessors.addAll(priorityOrderedPostProcessors);
invokeBeanDefinitionRegistryPostProcessors(priorityOrderedPostProcessors, registry);
//3、在执行实现了Ordered顺序接口的BeanDefinitionRegistryPostProcessor
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
List<BeanDefinitionRegistryPostProcessor> orderedPostProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(beanFactory, orderedPostProcessors);
registryPostProcessors.addAll(orderedPostProcessors);
invokeBeanDefinitionRegistryPostProcessors(orderedPostProcessors, registry);
//4、最后执行没有实现任何优先级或者是顺序接口的BeanDefinitionRegistryPostProcessors；
boolean reiterate = true;
while (reiterate) {
reiterate = false;
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName)) {
BeanDefinitionRegistryPostProcessor pp = beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class);
registryPostProcessors.add(pp);
processedBeans.add(ppName);
pp.postProcessBeanDefinitionRegistry(registry);
reiterate = true;
}
}
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
============再执行BeanFactoryPostProcessor接口的方法==============
//1、获取所有的BeanFactoryPostProcessor
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
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);
}
}
//2、看先执行实现了PriorityOrdered优先级接口的
sortPostProcessors(beanFactory, priorityOrderedPostProcessors);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
//3、在执行实现了Ordered顺序接口的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(beanFactory, orderedPostProcessors);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
//4、最后执行没有实现任何优先级或者是顺序接口的BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
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、注册BeanPostProcessor（Bean的后置处理器）
- 不同接口类型的BeanPostProcessor；在Bean创建前后的执行时机是不一样的，有BeanPostProcessor、InstantiationAwareBeanPostProcessor、等
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
//1、获取所有的 BeanPostProcessor（其实后置处理器都默认可以通过PriorityOrdered、Ordered接口来执行优先级）
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));
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();
List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
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);
}
}
//2、先注册PriorityOrdered优先级接口的BeanPostProcessor
sortPostProcessors(beanFactory, priorityOrderedPostProcessors);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
//3、再注册Ordered接口的
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(beanFactory, orderedPostProcessors);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
//4、最后注册没有实现任何优先级接口的
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
//5、最终注册 internal BeanPostProcessors.（比如MergedBeanDefinitionPostProcessor）
sortPostProcessors(beanFactory, internalPostProcessors);
ApplicationListenerDetector
registerBeanPostProcessors(beanFactory, internalPostProcessors);
//6、在Bean创建完成后检查是否是ApplicationListener，如果是注册一个
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
7、初始化MessageSource组件（做国际化功能；消息绑定，消息解析）
protected void initMessageSource() {
//1、获取BeanFactory
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//2、看容器中是否有id为messageSource的，类型是MessageSource的组件，如果有赋值给messageSource，如果没有自己创建一个DelegatingMessageSource
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;
//3、把创建好的MessageSource注册在容器中，以后获取国际化配置文件的值的时候，可以自动注入MessageSource； 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、初始化事件派发器
protected void initApplicationEventMulticaster() {
//1、获取BeanFactory
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//2、从BeanFactory中获取applicationEventMulticaster的ApplicationEventMulticaster；
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 {
//3、如果上一步没有配置；创建一个SimpleApplicationEventMulticaster
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
//4、将创建的ApplicationEventMulticaster添加到BeanFactory中，以后其他组件直接自动注入 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在子容器（子类）初初始化特殊的bean
10、给容器中将所有项目里面的ApplicationListener注册进来
protected void registerListeners() {
//首先在事件派发器中注册静态指定的事件监听器
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
//1、从容器中拿到所有的ApplicationListener并遍历
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
//2、将每个监听器添加到事件派发器中 getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
//3、派发之前步骤产生的事件；
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
11、初始化所有剩下的单实例bean
- 重点在方法preInstantiateSingletons初始化后剩下的单实例bean
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Pre-instantiating singletons in " + this);
}
//1、获取容器中的所有Bean，依次进行初始化和创建对象
List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans...
for (String beanName : beanNames) {
//2、获取Bean的定义信息；RootBeanDefinition
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
//3、Bean不是抽象的，是单实例的，是懒加载；
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
//3.1判断是否是FactoryBean；是否是实现FactoryBean接口的Bean
if (isFactoryBean(beanName)) {
final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
boolean isEagerInit;
if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
@Override
public Boolean run() {
return ((SmartFactoryBean<?>) factory).isEagerInit();
}
}, getAccessControlContext());
}
else {
isEagerInit = (factory instanceof SmartFactoryBean &&
((SmartFactoryBean<?>) factory).isEagerInit());
}
if (isEagerInit) {
getBean(beanName);
}
}
else {
//3.2不是工厂Bean。利用getBean(beanName);创建对象
getBean(beanName);
}
}
}
// Trigger post-initialization callback for all applicable beans...
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
//4.检查所有的Bean是否是SmartInitializingSingleton接口的；如果是；就执行afterSingletonsInstantiated()；
if (singletonInstance instanceof SmartInitializingSingleton) {
final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
smartSingleton.afterSingletonsInstantiated();
return null;
}
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
}
}
}
//AbstractBeanFactory.doGetBean
protected <T> T doGetBean(
final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
throws BeansException {
final String beanName = transformedBeanName(name);
Object bean;
//1、先获取缓存中保存的单实例Bean。如果能获取到说明这个Bean之前被创建过（所有创建过的单实例
//Bean都会被缓存起来）从private final Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256);获取的
Object sharedInstance = getSingleton(beanName);
if (sharedInstance != null && args == null) {
if (logger.isDebugEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
}
}
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
//2、缓存中获取不到，开始Bean的创建对象流程；
if (isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// Check if bean definition exists in this factory.
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// Not found -> check parent.
String nameToLookup = originalBeanName(name);
if (args != null) {
// Delegation to parent with explicit args.
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else {
// No args -> delegate to standard getBean method.
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
}
if (!typeCheckOnly) {
//3.1标记当前bean已经被创建
markBeanAsCreated(beanName);
}
try {
//3.2获取Bean的定义信息；
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
//3.3获取当前Bean依赖的其他Bean;如果有，按照getBean()把依赖的Bean先创建出来
String[] dependsOn = mbd.getDependsOn();
if (dependsOn != null) {
for (String dependsOnBean : dependsOn) {
if (isDependent(beanName, dependsOnBean)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dependsOnBean + "'");
}
registerDependentBean(dependsOnBean, beanName);
getBean(dependsOnBean);
}
}
//3.4启动单实例Bean的创建流程
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
// Explicitly remove instance from singleton cache: It might have been put there
// eagerly by the creation process, to allow for circular reference resolution.
// Also remove any beans that received a temporary reference to the bean.
destroySingleton(beanName);
throw ex;
}
}
});
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'");
}
try {
Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
}
});
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; consider " +
"defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
catch (BeansException ex) {
cleanupAfterBeanCreationFailure(beanName);
throw ex;
}
}
// Check if required type matches the type of the actual bean instance.
if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {
try {
return getTypeConverter().convertIfNecessary(bean, requiredType);
}
catch (TypeMismatchException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to convert bean '" + name + "' to required type [" +
ClassUtils.getQualifiedName(requiredType) + "]", ex);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
}
return (T) bean;
}
- AbstractAutowireCapableBeanFactory.createBean创建有依赖的bean并放入缓存中
略
12、finishRefresh完成BeanFactory的初始化创建工作
protected void finishRefresh() {
//1、初始化和生命周期有关的后置处理器；LifecycleProcessor
initLifecycleProcessor();
// 2、拿到前面定义的生命周期处理器（BeanFactory）；回调onRefresh()；
getLifecycleProcessor().onRefresh();
// 3、发布容器刷新完成事件
publishEvent(new ContextRefreshedEvent(this));
// 4、Participate in LiveBeansView MBean, if active.
LiveBeansView.registerApplicationContext(this);
}
网友评论