引言
上一期讲述了
BeanDefinitions的载入和注册，beanDefinition相当于spring对bean的数据抽象定义，这一期我们继续顺着的refresh方法往下讲
回到refresh方法
上一期其实主要是介绍了obtainFreshBeanFactory() 这一步，这一期我们继续接着往下看
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// 创建BeanFactory,并载入BeanDefinitions（重要）
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);
// 执行 BeanFactoryPostProcessors（实例化bean前修改bean定义信息）
invokeBeanFactoryPostProcessors(beanFactory);
// 注册 BeanPostProcessors（初始化bean前后执行）
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
// 国际化相关
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
// 初始化主题信息
onRefresh();
// Check for listener beans and register them.
registerListeners();
// 提前实例化化全部非延迟加载的单例类型
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();
}
}
}
prepareBeanFactory(beanFactory)
先看一下prepareBeanFactory的方法实现
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 配置容器的 classLoader
beanFactory.setBeanClassLoader(getClassLoader());
// 这是一个表达是语言处理器
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
// 属性编辑器
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// 配置了BeanPostProcessor的一个实现类
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
// 配置被忽略的依赖项（各种 Aware 实现类）
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// 修正依赖
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.
// 注册AOP相关的
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()));
}
// 配置Spring 默认环境变量bean
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());
}
}
这个方法做了什么事情呢，我们简单的来看一下
- 首先是配置了容器的默认
classLoader - 配置了一个语言器和一个属性编辑器
- 注册了一个
BeanPostProcessor接口的一个实现类，这个接口的具体用处下面马上会讲到 - 配置要自动注入时要被忽略的bean类型，可以看到这里配置的都是一些
Aware实现类，这些依赖项spring容器会统一设置 - 注册
aop相关的 - 配置
Spring默认环境变量bean(systemProperties, systemEnvironment, environment)
postProcessBeanFactory(beanFactory)
方法比较简短，通过查看代码，可知也是对beanFactory做一些配置的工作
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext, this.servletConfig));
beanFactory.ignoreDependencyInterface(ServletContextAware.class);
beanFactory.ignoreDependencyInterface(ServletConfigAware.class);
WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext, this.servletConfig);
}
invokeBeanFactoryPostProcessors(beanFactory)
可以看到主要逻辑在，PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors中，这里其实是spring留的一个扩展点，我们可以通过实现BeanFactoryPostProcessor来实现在 getBean之前的自定义扩展。现在我们就来看看它是在什么时候执行的
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()));
}
}
继续查看PostProcessorRegistrationDelegate.class
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// 存放已经执行的 BeanFactoryPostProcessor bean名字
Set<String> processedBeans = new HashSet<String>();
// 判断beanFactory类型是否为BeanDefinitionRegistry，只有BeanDefinitionRegistry类型的才支持BeanDefinitionRegistryPostProcessor的注册
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
// 存放手动加入的 BeanFactoryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
// 存放手动加入的 BeanDefinitionRegistryPostProcessor
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
// 如果是BeanDefinitionRegistryPostProcessor类型
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
// 执行 postProcessBeanDefinitionRegistry 方法
registryProcessor.postProcessBeanDefinitionRegistry(registry);
// 放入待执行容器中，之后会执行BeanFactoryPostProcessor接口的postProcessBeanFactory方法
registryProcessors.add(registryProcessor);
}
else {
// 放入待执行容器中，之后统一执行
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.
// 用于存放当前需要执行的 BeanDefinitionRegistryPostProcessor list
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 一 先执行类型为 PriorityOrdered 的BeanDefinitionRegistryPostProcessors
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);
// 将当前需要执行全部放入 待执行容器
registryProcessors.addAll(currentRegistryProcessors);
// 执行
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 清空已经执行过的
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 二 在执行类型为Ordered的BeanDefinitionRegistryPostProcessor
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后执行普通的 BeanDefinitionRegistryPostProcessors
boolean reiterate = true;
// 循环的目的是未了防止执行过程中有新的 postProcessorNames 加入
while (reiterate) {
reiterate = false;
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
reiterate = true;
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
// 执行待执行容器的中的 BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
// 直接执行手动加入的 BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// 以上执行完BeanDefinitionRegistryPostProcessor，现在开始执行BeanFactoryPostProcessor
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// 执行顺序和BeanDefinitionRegistryPostProcessor基本一致，先PriorityOrdered，再Ordered，最后普通的
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
// 存放 PriorityOrdered类型的BeanFactoryPostProcessor
List<String> orderedPostProcessorNames = new ArrayList<String>();
// 存放 Ordered类型的BeanFactoryPostProcessor
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
for (String ppName : postProcessorNames) {
if (processedBeans.contains(ppName)) {
// 这里跳过的是已经执行过的 BeanDefinitionRegistryPostProcessor
// 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.
// 先执行 PriorityOrdered
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
// 再执行 Ordered
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
// 最后执行普通的
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();
}
这个方法代码非常的多，夹杂着各种判断，看的眼花缭乱。我们简单理一下逻辑
-
BeanFactoryPostProcessor有一个子接口叫做BeanDefinitionRegistryPostProcessor，它的优先级是比BeanFactoryPostProcessor高的 - 方法的入参里有一个
List<BeanFactoryPostProcessor> beanFactoryPostProcessors，这个是容器通过addBeanFactoryPostProcessor方法手动加入的。这里的BeanDefinitionRegistryPostProcessor类型是优先级最高的 - 同时
BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor可以都实现两个接口(PriorityOrdered,Ordered)用来定义执行的顺序，其中PriorityOrdered优先级最高，其次Ordered，最后是没有实现任何Order接口的
综上三点，我们是可以得出上面一大坨代码的执行顺序了
- 首先是拿到手动加入的
BeanFactoryPostProcessor，挑出里面的BeanDefinitionRegistryPostProcessor类型，优先执行。 - 再拿到容器中的全部
BeanDefinitionRegistryPostProcessors，按照实现的排序接口顺序执行 - 执行
BeanDefinitionRegistryPostProcessors父类型BeanFactoryPostProcessor的方法 - 最后再拿到容器中全部
BeanFactoryPostProcessors并过滤到已经执行过的BeanDefinitionRegistryPostProcessors，按照顺序依次执行
registerBeanPostProcessors(beanFactory)
这里也是spring的一个扩展点，通过实现BeanPostProcessor接口来实现自定义逻辑，具体的执行时机，会在分析getBaan时讲到，这里的逻辑仅仅是将BeanPostProcessor用户自定义的BeanPostProcessor注册到容器
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;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
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);
}
}
// 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<BeanPostProcessor>();
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<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);
// 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).
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
这里的逻辑其实跟上面的逻辑非常的相似，其实也都在一个class中，唯一的区别是这里并没有执行，仅仅只是做了下排序后就注册进了容器中，留到后面的步骤中在执行。这里也简单的列一下这里的要点
-
BeanPostProcessor有一个子接口MergedBeanDefinitionPostProcessor,这个是最晚被注册进容器的 - 同样可以实现(
PriorityOrdered,Ordered)接口用来定义执行的顺序
initMessageSource()
国际化相关，这里就不做仔细分析了
initApplicationEventMulticaster()
顾名思义。就是spring用来初始化事情广播器的
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 + "]");
}
}
}
看一下这里的代码比较的简单，就是一个 if else，先尝试获取名字为APPLICATION_EVENT_MULTICASTER_BEAN_NAME类型为ApplicationEventMulticaster的 bean，如果没有获取到，则配置一个默认的bean (SimpleApplicationEventMulticaster)
onRefresh()
这里是留给子类实现的，没有什么逻辑
registerListeners()
注册一些监听器
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);
}
}
}
尾言
下篇会解析
finishBeanFactoryInitialization方法，并且会着重讲解初始化bean的整个生命周期
博客原文地址戳这里
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