日期：2019-03-28
备注：refresh主流程
/**
* @see AbstractApplicationContext#refresh()
*/
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
//准备此上下文以进行刷新
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
//这里是在子类中启动refreshBeanFactort()的地方
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
// 准备bean工厂以在此上下文中使用。
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
// 允许在上下文子类中对bean工厂进行后处理。
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
//调用beanFactory的后处理器，这些后处理器是在bean定义中向容器注册的,用户自定义的Spring的各种内置处理，都是在这个地方进行初始化的。比如：自定义ResourceEditorRegistrar；
//对priorityOrderedPostProcessors，orderedPostProcessors，BeanDefinitionRegistryPostProcessor进行注册，然后，在按顺序实例化，提前实例化这些接口下的bean。
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
// 注册bean的后处理器，在bean创建过程中调用
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
//对上下文中的消息源进行初始化
initMessageSource();
// Initialize event multicaster for this context.
//初始化上下文中的事件机制
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
//初始化其他的特殊bean
onRefresh();
// Check for listener beans and register them.
//检查监听bean并且将这些bean向容器注册
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
//实例化所有的(non-lazy-init)单利
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
//发布容器事件，结束refresh过程
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...
/**
* 重置Spring核心中的常见内省缓存，
* 从此我们开始可能再也不需要单例bean的元数据
*/
resetCommonCaches();
}
}
}
refresh主流程
4）postProcessBeanFactory(beanFactory)
允许在上下文子类中对bean工厂进行后处理。
默认实现为空，时提供给用户的入口，实现此方法，用来在beanFactory实例化之前做一些定制化的处理。
比如：org.springframework.web.context.support.GenericWebApplicationContext#postProcessBeanFactory(beanFactory)，忽略ServletContextAware，注册了一些scope；
@Override
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext));
beanFactory.ignoreDependencyInterface(ServletContextAware.class);
WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext);
}
5）invokeBeanFactoryPostProcessors(beanFactory)
调用beanFactory的后处理器，这些后处理器是在bean定义中向容器注册的,为用户提供的一些工具类：比如格式化日期的 ResourceEditorRegistrar;
/**@see AbstractApplicationContext#invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory)
*/
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//调用beanFactory中注册的后置处理器，按照ordered、PriorityOrdered接口来排序之后，顺序调用
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
// loadTimeWeaver 方式的切面，为beanFactory设置对应的转化类。在实例化bean的时候，会用到。
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
主要的流程在第一步：
顺序：1. BeanDefinitionRegistryPostProcessor
手动设置的 BeanDefinitionRegistryPostProcessor =>排序后的 PriorityOrdered => 排序后的 Ordered =>其他的 BeanDefinitionRegistryPostProcessor
2. BeanFactoryPostProcessor
排序后的 PriorityOrdered => 排序后的 Ordered => 其他的 BeanFactoryPostProcessor
//PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
//存放所有的 PostProcessor 的名称
Set processedBeans = new HashSet();
// DefaultListableBeanFactory 实现了 BeanDefinitionRegistry接口的
if (beanFactory instanceof BeanDefinitionRegistry) {
//强转为 BeanDefinitionRegistry
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
// 存放 非BeanDefinitionRegistryPostProcessor
List regularPostProcessors = new LinkedList();
//存放 BeanDefinitionRegistryPostProcessor
List registryProcessors = new LinkedList();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//注册到BeanFactory中
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// Separate between BeanDefinitionRegistryPostProcessors that implement
// PriorityOrdered, Ordered, and the rest.
//用来暂时存放排序后的 BeanDefinitionRegistryPostProcessor，调用过后，就clear
List currentRegistryProcessors = new ArrayList();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 筛选出 PriorityOrdered 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);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
//放入排序之后的 BeanDefinitionRegistryPostProcessor
registryProcessors.addAll(currentRegistryProcessors);
//依次调用注册
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 筛选出 Ordered BeanDefinitionRegistryPostProcessors
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
boolean reiterate = true;
//在while循环中调用，for循环，会有其他线程同时对beanFactory注册bean么
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.
// 前面调用的是BeanDefinitionRegistryPostProcessor,可能在调用的对beanFactory注册新的
// 现在调用 BeanFactoryPostProcessor 注册器的后置处理器
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
// 现在调用 其他的 BeanFactoryPostProcessor 注册器的后置处理器
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}else {
// Invoke factory processors registered with the context instance.
// 如果beanFactory不是
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!
// 查找 BeanFactoryPostProcessor 接口下的类
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
//实现 priorityOrdered 接口的
List priorityOrderedPostProcessors = new ArrayList();
//实现 ordered 接口的
List orderedPostProcessorNames = new ArrayList();
// 其他的
List 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);
}
}
//依次调用 后置处理
// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
List 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 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();
}
在调用后置处理器时，会调用getBean方法，得到后置处理器的实例，所以，这个启动过程，这里是第一次出来实例化。
调用后置处理器的部分，如下。
/**
* BeanDefinitionRegistryPostProcessor 注册器的后置处理器
* Invoke the given BeanDefinitionRegistryPostProcessor beans.
*/
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection postProcessors, BeanDefinitionRegistry registry) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}
/**
* BeanFactoryPostProcessor 注册器的后置处理器
* Invoke the given BeanFactoryPostProcessor beans.
*/
private static void invokeBeanFactoryPostProcessors(
Collection postProcessors, ConfigurableListableBeanFactory beanFactory) {
for (BeanFactoryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanFactory(beanFactory);
}
}
/**
* Register the given BeanPostProcessor beans.
*/
private static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, List postProcessors) {
for (BeanPostProcessor postProcessor : postProcessors) {
beanFactory.addBeanPostProcessor(postProcessor);
}
}