Spring 启动流程--BeanDefinitionRegistryPostProcessor与BeanFactoryPostProcessor调用时机
1.先看看这两个接口
public interface BeanFactoryPostProcessor {
/**
* Modify the application context's internal bean factory after its standard
* initialization. All bean definitions will have been loaded, but no beans
* will have been instantiated yet. This allows for overriding or adding
* properties even to eager-initializing beans.
* @param beanFactory the bean factory used by the application context
* @throws org.springframework.beans.BeansException in case of errors
*/
void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;
}
// 因为BeanDefinitionRegistryPostProcessor 是 BeanFactoryPostProcessor 的子接口,则
// BeanDefinitionRegistryPostProcessor 的实现类,将会实现这两个接口的两个方法
public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {
/**
* Modify the application context's internal bean definition registry after its
* standard initialization. All regular bean definitions will have been loaded,
* but no beans will have been instantiated yet. This allows for adding further
* bean definitions before the next post-processing phase kicks in.
* @param registry the bean definition registry used by the application context
* @throws org.springframework.beans.BeansException in case of errors
*/
void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
}
2.启动过程中的执行过程
2.1 启动Spring
@Test
public void test01(){
AnnotationConfigApplicationContext applicationContext =
new AnnotationConfigApplicationContext(ExtConfig.class);
applicationContext.close();
}
2.2 调用refresh() 方法
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
this();
register(annotatedClasses);
refresh();
}
@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);
//调用注册在工厂的处理器BeanFactoryPostProcessors
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();
}
}
}
2.3详细来看下invokeBeanFactoryPostProcessors 方法
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 主要在此方法调用
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()));
}
}
2.4实例化BeanFactoryPostProcessors,并将其排序后依次调用
-
先处理实现了 BeanDefinitionRegistryPostProcessor 接口的
-
从容器中获取BeanDefinitionRegistryPostProcessor 类型的beanName
-
根据其优先级顺序,依次调用从 BeanDefinitionRegistryPostProcessor 接口中实现的 postProcessBeanDefinitionRegistry()方法
-
再调用所有从BeanFactoryPostProcessor 接口中实现的 postProcessBeanFactory()方法
-
再处理实现了 BeanDefinitionRegistryPostProcessor 接口的,但会排除实现了 BeanDefinitionRegistryPostProcessor 接口的
-
也是按优先级循序来调用其postProcessBeanFactory()方法
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> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
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.
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
// 首先 调用实现了PriorityOrdered 接口的BeanDefinitionRegistryPostProcessors
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//拿到所有BeanDefinitionRegistryPostProcessors 类型的beanname,循环判断当前是否实现了PriorityOrdered优先级接口
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
// 如果实现了,则通过getBean()方法来获取对应的对象,并加入到List中(currentRegistryProcessors)
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
// 把每次新添加的beanName 保存起来,代表其已经被处理过了,下面将会判断正在处理的BeanDefinitionRegistryPostProcessor 以前是否处理过
processedBeans.add(ppName);
}
}
// 排序这些 BeanDefinitionRegistryPostProcessor
sortPostProcessors(currentRegistryProcessors, beanFactory);
// registryProcessors 用来保存所有的BeanDefinitionRegistryPostProcessor类型的bean
registryProcessors.addAll(currentRegistryProcessors);
//BeanDefinitionRegistryPostProcessor 依次回调其postProcessBeanDefinitionRegistry()方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 清空list,接下来将被拿来存放实现了Ordered 接口的
currentRegistryProcessors.clear();
// 再次拿到所有的 BeanDefinitionRegistryPostProcessor 类型的 beanName
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
// 又一次循环遍历它们
for (String ppName : postProcessorNames) {
// 如果当前的这个beanName,在上面没有处理过,且还实现了Ordered接口
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
// 则获取到其实例,并加入到currentRegistryProcessors 集合中
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
// 把每次新添加的beanName 保存起来,代表其已经被处理过了
processedBeans.add(ppName);
}
}
// 排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
// registryProcessors 用来保存所有的BeanDefinitionRegistryPostProcessor类型的bean
registryProcessors.addAll(currentRegistryProcessors);
// 回调其postProcessBeanDefinitionRegistry()方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 清空list,接下来将被拿来存放其他的 BeanDefinitionRegistryPostProcessor 的实例
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最终调用余下的BeanDefinitionRegistryPostProcessors,直到容器中不再有该类型的定义信息;因为 //BeanDefinitionRegistryPostProcessors 中可以新注册Bean,此Bean也可能是BeanDefinitionRegistryPostProcessors 类型的,所以此需要循环
//直到已经没有需要处理的了
boolean reiterate = true;
while (reiterate) {
reiterate = false;
// 依然是拿到所有的 BeanDefinitionRegistryPostProcessor 类型的 beanName
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
// 挨个遍历
for (String ppName : postProcessorNames) {
// 如果发现有前面没有处理过的
if (!processedBeans.contains(ppName)) {
// 则将其添加到 集合中
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
// 把每次新添加的beanName 保存起来,代表其已经被处理过了
processedBeans.add(ppName);
// 添加了新的 BeanDefinitionRegistryPostProcessor ,则表示还需要再循环一遍
reiterate = true;
}
}
// 排序上面循环中添加的
sortPostProcessors(currentRegistryProcessors, beanFactory);
// registryProcessors 用来保存所有的BeanDefinitionRegistryPostProcessor类型的bean
registryProcessors.addAll(currentRegistryProcessors);
// 执行回调
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// 清空集合
currentRegistryProcessors.clear();
}
//现在，调用到目前为止处理的所有处理器的postProcessBeanFactory回调(因为实现BeanDefinitionRegistryPostProcessor接口的类,也是
//BeanFactoryPostProcessor 类型的子类,现在就来回调从BeanFactoryPostProcessor接口中继承来的postProcessBeanFactory()方法 )
// registryProcessors 保存了上面获取到的所有的BeanDefinitionRegistryPostProcessor bean
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!
// 从容器中获取所有BeanFactoryPostProcessor 类型的BeanName数组
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
// 遍历所有的BeanFactoryPostProcessor类型BeanName数组
for (String ppName : postProcessorNames) {
// 如果在第一阶段执行过的BeanFactoryPostProcessor 将在这跳过
//processedBeans 保存的是实现了BeanDefinitionRegistryPostProcessor 接口的全类名,而BeanDefinitionRegistryPostProcessor 又是BeanFactoryPostProcessors 的子接口,且其postProcessBeanFactory方法已经在前面调用过了,此处将会跳过其调用
if (processedBeans.contains(ppName)) {
// skip - already processed in first phase above
}
// 如果是实现了PriorityOrdered 接口的,优先创建
//如果容器中没有,调用beanFactory.getBean方法,则会创建当前bean
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
// 将实现了PriorityOrdered 接口的 BeanFactoryPostProcessor 实例添加到 priorityOrderedPostProcessors List中
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
}
//将实现了Ordered接口的,将其beanName添加到下面数组中
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
// 将实现了Ordered接口的 BeanFactoryPostProcessor 实例添加到 orderedPostProcessorNames List中
orderedPostProcessorNames.add(ppName);
}
else {
//没有实现前两种接口的,将其beanName添加到下面的List中
nonOrderedPostProcessorNames.add(ppName);
}
}
// 首先,先排序实现了 PriorityOrdered 接口的BeanFactoryPostProcessors
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
//然后依次调用它的postProcessBeanFactory()方法
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
//接下来排序实现了创建实现了Ordered接口的
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
// 排序 Ordered接口的BeanFactoryPostProcessors ,然后依次调用它
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// 最后实例化,并调用其他的 BeanFactoryPostProcessors
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();
}
2.5 依次调用BeanDefinitionRegistryPostProcessor 的postProcessBeanDefinitionRegistry方法
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}
2.6依次回调其postProcessBeanFactory方法,并将beanFactory实例传入
private static void invokeBeanFactoryPostProcessors(
Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {
for (BeanFactoryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanFactory(beanFactory);
}
}