文章目錄
-
- 1. refresh()概覽
- 2. refresh()内部方法詳解
-
- 2.1 prepareRefresh()
- 2.2 prepareBeanFactory(beanFactory)
- 2.3 postProcessBeanFactory(beanFactory)
- 2.4 invokeBeanFactoryPostProcessors(beanFactory)
-
- 2.4.1 處理BeanDefinitionRegistryPostProcessor
-
- 2.4.1.1 處理PriorityOrdered優先級
- 2.4.1.2 處理Ordered優先級
- 2.4.1.3 處理其他剩餘優先級的
- 2.4.2 處理BeanFactoryPostProcessor
- 2.5 registerBeanPostProcessors(beanFactory)
- 2.6 initMessageSource()
- 2.7 initApplicationEventMulticaster()
- 2.8 onRefresh()
- 2.9 registerListeners()
- 2.10 finishBeanFactoryInitialization(beanFactory)
- 2.11 finishRefresh()
上一篇文章 《spring5源碼閱讀(一)》中,我們分析了AnnotationConfigApplicationContext構造方法中3大方法的前兩個,這一節,繼續分析第3個方法refresh()。
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
//1.會首先調用父類GenericApplicationContext中的構造方法,初始化工廠bean為new DefaultListableBeanFactory()
//2.調用自己的構造方法,初始化了一個讀取器:AnnotatedBeanDefinitionReader reader;一個掃描器:ClassPathBeanDefinitionScanner scanner
//3.在reader的初始化構造方法中,還注冊了6個post processors
this();
//注冊bean,注冊就是把bean都放在某個地方,一個并發map中,Map<String, BeanDefinition> beanDefinitionMap
//這調用了AnnotatedBeanDefinitionReader reader的注冊方法
register(annotatedClasses);
//執行個體化bean
refresh();
}
前兩個方法主要實作了BeanDefinition的注冊,就是放到了容器的某個map中。
第3個方法,整體上就是實作bean的執行個體化。包括預設後置處理器,以及的配置類(@Configuration注解修飾的),以及我們自定義的bean(加了@Componet等類似注解的)。
由于内容比較多,在這篇文章中,我們不進行過多的代碼深入擴充;本篇我們隻是對整體的流程有一個比較清晰的認識即可,比較深入擴充的内容,我們在其他文章中單獨分析,文章連接配接會貼在對應的代碼處。
1. refresh()概覽
先看下refresh()的代碼:
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
//前期準備;記錄了容器啟動時間;容器狀态;重新整理一些在此方法之前就可能已經存在的監聽器
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
//最終得到DefaultListableBeanFactory,也就是在this()方法中通過父類構造函數初始化的那個bean factory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
//準備bean factory,初始化工廠的一些标準固定的容器特性
//因為後邊一系列容器初始化操作,都是基于beanFactory,是以前期準備得充足
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
//空方法,用于子類擴充功能
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
//執行個體化并執行之前已經注冊了的各種BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
//執行個體化 攔截bean建立的處理器BeanPostProcessor;
//這裡的注冊,是指把執行個體化的BeanPostProcessor存到beanFactory的某個list中
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
//初始化容器的MessageSource類型的bean,MessageSource用于解析消息
initMessageSource();
// Initialize event multicaster for this context.
//初始化容器的事件廣播
//用于管理若幹ApplicationListener對象,并向他們推送消息
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
//空方法,在特定的子類中 初始化其他特殊bean
onRefresh();
// Check for listener beans and register them.
//注冊實作了ApplicationListener接口的監聽者
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
//執行個體化剩下的單例bean,完成全部bean的執行個體化,除了懶加載的
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
//最後一步,完成此重新整理方法,釋出完成事件
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();
}
}
}
差不多有12個方法,每個方法擴充開來,可能都比較複雜,下面我們單個方法分析。
2. refresh()内部方法詳解
2.1 prepareRefresh()
此方法的主要作用就是前期準備;記錄了容器啟動時間;容器狀态;重新整理一些在此方法之前就可能已經存在的監聽器;初始化事件集合等。
此方法沒有什麼特别重要的地方,可以粗略看下,然後跳過。
protected void prepareRefresh() {
// Switch to active.
//容器啟動時刻
this.startupDate = System.currentTimeMillis();
//容器激活狀态,預設沒有關閉
this.closed.set(false);
//容器激活狀态,預設激活的
this.active.set(true);
if (logger.isInfoEnabled()) {
logger.info("Refreshing " + this);
}
// Initialize any placeholder property sources in the context environment.
//空方法
initPropertySources();
// Validate that all properties marked as required are resolvable:
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
//執行refresh之前就已經注冊的listeners集合,如果沒有,就初始化集合;
//調試發現是null的
if (this.earlyApplicationListeners == null) {
this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// Reset local application listeners to pre-refresh state.
//如果不為空,重新設定到applicationListeners監聽器集合
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
//事件集合初始化
this.earlyApplicationEvents = new LinkedHashSet<>();
}
2.2 prepareBeanFactory(beanFactory)
準備bean factory,初始化工廠的一些标準固定的容器特性,因為後邊一系列容器初始化操作,都是基于beanFactory,是以前期準備得充足。
其中入參通過以下方式得到:
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
跟代碼進去,最終擷取到的是擷取到的是DefaultListableBeanFactory,其實在上篇中的this()中就已經初始化了。
下面看prepareBeanFactory的代碼:
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));
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());
}
}
都是些bean工廠本身的固有特性的初始化操作;
注意beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
這個屬于神功周期中的一個環節,在初始化bean的時候,會執行。
其他也不是特别重要,看一錯略看過。
2.3 postProcessBeanFactory(beanFactory)
空方法,用于子類擴充功能。
2.4 invokeBeanFactoryPostProcessors(beanFactory)
此方法比較重要;執行個體化并執行之前已經注冊了的各種BeanFactoryPostProcessor。
BeanFactoryPostProcessor的作用就是在容器執行個體化具體的普通bean(比如我們自己定義的一個service類)之前,去修改(定制化)bean的相關定義。
進入方法:
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//委派模式,委派PostProcessorRegistrationDelegate類來實作具體邏輯
//getBeanFactoryPostProcessors()這裡得到的是empty
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()));
}
}
核心代碼在第一行,使用了委派模式;核心實作在委派類中。
我們繼續進入委派類中,會發現代碼比較長,主要是因為要處理不同類型的BeanFactoryPostProcessor;
但是仔細理以下,其實邏輯并不複雜,就是在查找各種BeanFactoryPostProcessor然後i将其執行個體化。
BeanFactoryPostProcessor總共有兩種:
1.BeanFactoryPostProcessor
2.BeanDefinitionRegistryPostProcessor,它繼承了第一種。
spring機制要求先處理直接實作了第二種的Post Processor,然後處理直接實作了第一種的;
在處理每一種Post Processor時,還要分優先級情況PriorityOrdered, Ordered。
整體上流程如下:
1.處理BeanDefinitionRegistryPostProcessor
-------1.1 處理PriorityOrdered優先級的
-------1.2處理Ordered優先級的
-------1.3處理其他優先級的
2.處理BeanFactoryPostProcessor
-------2.1 處理PriorityOrdered優先級的
-------2.2處理Ordered優先級的
-------2.3處理其他優先級的
由于方法代碼比較長,我們從上到下拆分代碼分析,一行不漏:
2.4.1 處理BeanDefinitionRegistryPostProcessor
在具體處理具體的優先級之前,先進行了如下for循環代碼,這裡beanFactoryPostProcessors實際預設是空的,除非手動調用AbstractApplicationContext#addBeanFactoryPostProcessor方法;因為是空的,我們暫時跳過。
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
//如果有BeanDefinitionRegistryPostProcessor類型的後置處理器,先處理這種;
//總共也就兩種:
//1.BeanFactoryPostProcessor
//2.BeanDefinitionRegistryPostProcessor,它繼承了第一種
//存儲所有執行個體化的bean名字
Set<String> processedBeans = new HashSet<>();
//這裡是true,因為beanFactory是DefaultListableBeanFactory,實作了BeanDefinitionRegistry
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
//正常類型的Post Processors"執行個體"清單,這裡是相對于下一行BeanDefinitionRegistryPostProcessor
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
//BeanDefinitionRegistry相關的Post Processors "執行個體"清單
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
//正常情況下,beanFactoryPostProcessors是empty;除非調用了AbstractApplicationContext#addBeanFactoryPostProcessor方法
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
//周遊找到類型為BeanDefinitionRegistryPostProcessor的post processor,如果有,優先處理這個類型
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
//執行後置處理方法
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
} else {
//存到list後邊用
regularPostProcessors.add(postProcessor);
}
}
//後續代碼在下節...
2.4.1.1 處理PriorityOrdered優先級
// 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.
//翻譯上邊:這裡先不初始化FactoryBeans,我們需要保留所有正常bean的狀态為非初始化狀态,好讓post-processors能對它們發揮作用
//實作了PriorityOrdered, Ordered或者其他接口的,要分開處理。
//和上邊registryProcessors一樣,隻是這個用于暫時排序用,排完序就清空
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
//1.首先,執行實作了PriorityOrdered接口的BeanDefinitionRegistryPostProcessors,這種類型的優先級最高
//1.1 先找到beanName,就是從beanFactory中get出來
//之前在this方法中,注冊了6個 post processor,第一個就是ConfigurationClassPostProcessor,它實作了PriorityOrdered接口
//是以這裡數組長度是1
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//1.2 周遊beanName,執行個體化
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
//beanFactory是DefaultListableBeanFactory
//getBean是其父類AbstractBeanFactory中的方法,調用完getBean就完成了執行個體化
//這裡beanFactory.getBean方法是個比較重要的方法
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//根據優先級順序排序,每個post processor 裡面都有個gerOrder指定了order的值
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
//1.3 執行後置處理方法
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
//這一小波處理完了,清空
currentRegistryProcessors.clear();
//後續代碼在下節...
步驟說明:
1.先從beanFactory(容器)中查詢到所有BeanDefinitionRegistryPostProcessor類型的bean名字。這個是很容易get到的,我們不展開了。因為在上篇文章中,已經把所有bean的定義和名字都注冊到了容器中,要麼存在map中,要麼存在list中。
2.周遊這些名字,并判斷有沒有實作PriorityOrdered接口,沒實作的不處理;
3.如果就是我們找的PriorityOrdered類型的,那麼就通過beanFactory.getBean方法執行個體化bean;這個beanFactory.getBean因為代碼比較多,我們單獨放在下篇文章中分析《spring5源碼閱讀(三)》,這裡我們知道它能執行個體化bean就行。
4.把挑選出來的post processor執行個體清單根據order排序;每個processor都指定了order(通過内部的gerOrder方法可擷取),越大優先級越低。
5.最後就是執行這這些後置處理器的内部接口方法了。當然不同的實作類有不同的實作。
通過打斷點,我們可以發現,這個for循環後,有一個符合條件的post processor,他就是ConfigurationClassPostProcessor,還記得上篇文章中的this()中,我們說了注冊了6個bean定義嘛,就是其中第一個。
ConfigurationClassPostProcessor的後置處理方法postProcessBeanDefinitionRegistry(),我們暫時不展開了,大緻上是處理了一些@Configuration修飾的配置類,然後進一步派生其他bean定義(比如我們自定義的model,mapper啥的)。
2.4.1.2 處理Ordered優先級
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
//2.然後執行個體化實作了Ordered的BeanDefinitionRegistryPostProcessors
//2.1這裡又重新拉取了一遍,同1.1
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
//2.2 周遊beanName,執行個體化
for (String ppName : postProcessorNames) {
//上邊已經處理了PriorityOrdered類型的,是以這裡要排除掉
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();
//後續代碼在下節...
步驟說明:
同上一小節邏輯,隻是這一段代碼處理的是實作了Ordered接口的處理器。
注意PriorityOrdered接口繼承了Ordered接口。實作了PriorityOrdered的,理論上也實作了Order,也能被getBeanNamesForType出來。是以循環内部要先排除那些實作PriorityOrdered的。
2.4.1.3 處理其他剩餘優先級的
上面PriorityOrdered和Ordered兩種類型的處理完了,要繼續處理其他剩餘的。
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//3.最後執行個體化 剩下的,既不是PriorityOrdered類型,也不是Ordered類型的
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();
}
//後續代碼在下節...
步驟和上面是一樣的。
隻是這裡是個while循環,為啥要循環呢,因為beanFactory.getBeanNamesForType查出來的處理完畢後,在這個處理過程中,可能會有新的bean被spring發現,并注冊到容器中。
最後還剩兩行,也說一下:
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
這裡執行postProcessBeanFactory接口中的的回調方法,因為前邊子類BeanDefinitionRegistryPostProcessor接口的方法已經優先執行了,但是父類BeanFactoryPostProcessor中,也有一個接口方法,同樣需要執行。
2.4.2 處理BeanFactoryPostProcessor
上一節,說的是實作了BeanFactoryPostProcessor的子類BeanDefinitionRegistryPostProcessor接口的一些後置處理器。
這一節,是處理那些直接實作BeanFactoryPostProcessor接口的後置處理器。
我們就不在繼續細分小節詳細說,因為整體邏輯基本和2.4.1一樣。
直接貼代碼吧,上邊流程弄明白了的話,看這裡就會發現一樣的。
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
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)) {
//前面可能已經處理過了,跳過
// 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();
}
2.5 registerBeanPostProcessors(beanFactory)
本方法作用是執行個體化BeanPostProcessor,然後注冊到beanFactory中;
BeanPostProcessor的作用是攔截bean建立,也就是在bean執行個體化的時候(執行個體化前後),能插入一些額外的動作。
看代碼:
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}
仍然是委派模式,繼續進入:
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
//從beanFactory查詢之前注冊的BeanPostProcessor類型的bean名字
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
//執行個體化一個BeanPostProcessorChecker,用于記錄日志資訊,比如當一個bean沒有被任何後置處理器處理時
//BeanPostProcessorChecker是一個内部類,實作了BeanPostProcessor接口
// 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.
//這裡也分為PriorityOrdered,Ordered, and 其他 3中情況分開處理;是以先周遊一遍,把類型分開;
//周遊時候,順便把PriorityOrdered執行個體化了
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
//是否架構内部使用的PostProcessor
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.
//首先注冊實作了PriorityOrdered接口的,注冊就是把執行個體化的ostProcessors放到容器的list結合中
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
//然後注冊Ordered實作了Ordered接口的
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.
//最後注冊其他類型的
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.
//最後注冊内部類型的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).
//初始化一個類,用于監聽器的探測
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
流程比較簡單,
1.從beanFactory中查找到所有BeanPostProcessor類型的bean名字;
2.PriorityOrdered,Ordered, 和其他共 3中情況分開執行個體化化,并注冊到beanFactory中,注意并沒有執行回調方法。
2.6 initMessageSource()
beanFactory有一個MessageSource類型的屬性,在這裡初始化它;
MessageSource用于解析消息。提供了若幹擷取消息的方法。
protected void initMessageSource() {
//beanFactory是DefaultListableBeanFactory;
//其實這裡沒必要從新擷取beanFactory,直接從外邊傳進來不是更好嘛
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
//這個if進不去
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.
//執行個體化DelegatingMessageSource并添加到單例池中
DelegatingMessageSource dms = new DelegatingMessageSource();
dms.setParentMessageSource(getInternalParentMessageSource());
this.messageSource = dms;
//注冊到單例池singletonObjects 中
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 + "]");
}
}
}
2.7 initApplicationEventMulticaster()
初始化一個ApplicationEventMulticaster,放在beanFactory的單例池中,
用于管理ApplicationListener,預設使用SimpleApplicationEventMulticaster。
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 + "]");
}
}
}
2.8 onRefresh()
空方法;
2.9 registerListeners()
2.7節執行個體化了一個ApplicationEventMulticaster,用于管理ApplicationListener。
這一節的方法就是往ApplicationEventMulticaster中注冊,最終放在了一個set中。
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...
//廣播事件到對應的監聽器;
//earlyApplicationEvents是在第一個方法prepareRefresh()中初始化的
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
2.10 finishBeanFactoryInitialization(beanFactory)
執行個體化剩下的單例bean,完成全部bean的執行個體化,除了懶加載的 ;
2.11 finishRefresh()
最後一步,完成此重新整理方法,釋出完成事件;
protected void finishRefresh() {
// Clear context-level resource caches (such as ASM metadata from scanning).
clearResourceCaches();
// Initialize lifecycle processor for this context.
initLifecycleProcessor();
// Propagate refresh to lifecycle processor first.
//執行LifecycleProcessor的方法
getLifecycleProcessor().onRefresh();
// Publish the final event.
//釋出完成時間給所有的監聽者
publishEvent(new ContextRefreshedEvent(this));
// Participate in LiveBeansView MBean, if active.
LiveBeansView.registerApplicationContext(this);
}