總結
額。。。寫得並不是很好,不過通過這個來強迫自己去梳理下整個流程,加深印象,也是闊以的
最後,spring的註釋是寫得真的全啊!!!
過程總結:
- 項目啓動
- 做創建刷新上下文前的各種準備工作
- 下面開始裝配bean
- 調用BeanDefinitionRegistryPostProcessor加載bean定義
- 調用BeanFactoryPostProcessor修改替換bean定義裏面的屬性值(${…}})
- 遍歷加載的定義,開始裝配bean
- 如果是單例模式先查緩存,緩存直接就返回
- 判斷是不是正在構建的Prototype bean,是就直接報異常
- 如果父BeanFactory不爲空,並且沒有bean定義,則調用父BeanFactory獲取bean
- 標記bean已經構建
- 檢查bean是否abstract類,是直接報錯
- 如果有@DependsOn,先構建被依賴的bean,並且記錄依賴關係
- 開始bean構建
13.1. 處理@Lookup註解
13.2. 調用InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation
13.3. 通過構造函數創建對象
13.4. 調用MergedBeanDefinitionPostProcessor#postProcessMergedBeanDefinition接口
13.5. 初始化bean屬性:
13.5.1. 調用InstantiationAwareBeanPostProcessor#postProcessAfterInstantiation方法
13.5.2.給@Autowired屬性注入對象
13.5.3. 調用InstantiationAwareBeanPostProcessor#postProcessPropertyValues方法
13.6. 初始化bean:
13.6.1 調用BeanPostProcessor#postProcessBeforeInitialization方法(@PostConstruct),
13.6.2 調用afterPropertiesSet方法或者指定的init method,
13.6.3 執行BeanPostProcessor#postProcessAfterInitialization方法
13.6.4 註冊爲DisposableBean - 如果需要類型轉換的則進行轉換
涉及spring的功能:
- @Conditional:是在bean定義加載階段進行判斷
- @Bean:註解了@Bean的方法,也是在bean定義階段被作爲bean處理,加載到定義中
- @PriorityOrdered:比@Oordered先執行
- 單例模式:第一次構建後會放入到緩存中,後續都是從緩存中取
- @DependsOn:bean構建前先構建@DependsOn指定的對象,並且最後銷燬的時候,依賴方會先被銷燬
- 構造函數:調用構造函數時,屬性還沒被初始化,除非指定了構造參數
- InitializingBean:在bean的屬性配置完成後纔會調用
過程
總流程:
SpringApplication#run
SpringApplication#createAndRefreshContext
SpringApplication#refresh
AbstractApplicationContext#refresh
下面是bean加載流程,這次主要關注3:bean定義的加載和7:構建bean,這兩個主要流程
- 上下文準備
- beanFactory的配置
- 調用所有BeanDefinitionRegistryPostProcessor#postProcessBeanDefinitionRegistry和BeanFactoryPostProcessor#postProcessBeanDefinitionRegistry方法:invokeBeanFactoryPostProcessors(beanFactory)
- 初始化MessageSource
- 初始化事件廣播器
- 註冊BeanPostProcessor(沒有調用):registerBeanPostProcessors(beanFactory)
- 構建bean並放入容器中:finishBeanFactoryInitialization(beanFactory)
- 初始化並調用LifecycleProcessor的onRefresh方法,發送事件
@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.
// 獲取BeanFactory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
// 配置BeanFactory
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
// 調用BeanFactoryPostProcessor,
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
// 註冊BeanPostProcessor(沒有調用)
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
// 初始化事件廣播器
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
// 註冊監聽器ApplicationListener
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
// 構建bean並放入容器中
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
// 初始化並調用LifecycleProcessor的onRefresh方法,發送事件
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();
}
}
}
bean定義:BeanDefinition
先來看看bean定義是什麼
bean定義用來描述bean,後續bean構建的時候就是根據bean定義來構建,下面是bean定義的一個結構圖,
bean定義裏面的內容,大概內容看方法名字基本就知道了,包含了諸如:類型、構建工廠、scope、構建方法、屬性等的信息
AnnotatedBeanDefinition在BeanDefinition基礎上擴展了對註解相關信息的支持
調用所有BeanFactoryPostProcessor(包含BeanDefinitionRegistryPostProcessor)
BeanFactoryPostProcessor實際上也分爲兩類:BeanFactoryPostProcessor和BeanFactoryPostProcessor的子類BeanDefinitionRegistryPostProcessor
過程:
AbstractApplicationContext#invokeBeanFactoryPostProcessors
PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
額。。。這個方法看着很複雜,但其實總體上可以劃分爲兩塊:執行BeanDefinitionRegistryPostProcessor、執行BeanFactoryPostProcessor,下面看下具體執行流程
- 如果傳入的beanFactory是BeanDefinitionRegistry的實例
1.1 遍歷參數傳入的beanFactoryPostProcessors,如果是BeanFactoryPostProcessor先放到列表中,如果是BeanDefinitionRegistryPostProcessor,直接執行它的postProcessBeanDefinitionRegistry方法
1.2 通過beanFactory#getBeanNamesForType方法查出BeanDefinitionRegistryPostProcessor的實現對象,然後分爲三組:a.實現了PriorityOrdered接口的 b.實現了Ordered接口 c.其他
1.3 對a組排序,然後依次postProcessBeanDefinitionRegistry方法
1.4 對b組排序,然後依次postProcessBeanDefinitionRegistry方法
1.5 然後依次執行c組的postProcessBeanDefinitionRegistry方法
1.6 最後再執行在1.1分出來的BeanFactoryPostProcessor的方法 - 如果傳入的beanFactory不是BeanDefinitionRegistry的實例,則直接執行傳參beanFactoryPostProcessors的BeanFactoryPostProcessor#postProcessBeanFactory方法
- 通過beanFactory#getBeanNamesForType方法查出BeanFactoryPostProcessor的實現對象,然後分爲三組:a.實現了PriorityOrdered接口的 b.實現了Ordered接口 c.其他
3.1 對a組排序,然後依次postProcessBeanFactory方法
3.2 對b組排序,然後依次postProcessBeanFactory方法
3.3 然後依次執行c組的postProcessBeanFactory方法
P.S.這塊看起來比較複雜,感覺是因爲兩塊的代碼風格寫起來不一致,第一塊的3組的獲取是調用了3次getBeanNamesForType方法,然後每次根據不同條件來取出對應的bean,導致代碼很多且複雜;第二塊,是調一次接口,一次循環直接分成3組,後面一次執行,這樣看起來更舒服,更優雅
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);
}
}
// 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.
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
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);
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
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);
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
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);
}
// 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<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);
}
}
// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
sortPostProcessors(beanFactory, priorityOrderedPostProcessors);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(beanFactory, orderedPostProcessors);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other 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();
}
BeanDefinitionRegistryPostProcessor:
按執行順序,先來看下BeanDefinitionRegistryPostProcessor
定義:
BeanDefinitionRegistryPostProcessor是屬於BeanFactoryPostProcessor的子類,會在BeanFactoryPostProcessor#postProcessBeanFactory執行前執行postProcessBeanDefinitionRegistry方法(從上面的執行流程可以看出來),只加載定義不構建bean,並且在BeanFactoryPostProcessor基礎上,可以註冊更多的bean定義信息,這些定義信息能定義BeanFactoryPostProcessor(渣翻。。。)
其實整個看來,就是負責bean定義的加載
/**
* Extension to the standard {@link BeanFactoryPostProcessor} SPI, allowing for
* the registration of further bean definitions <i>before</i> regular
* BeanFactoryPostProcessor detection kicks in. In particular,
* BeanDefinitionRegistryPostProcessor may register further bean definitions
* which in turn define BeanFactoryPostProcessor instances.
*
* @author Juergen Hoeller
* @since 3.0.1
* @see org.springframework.context.annotation.ConfigurationClassPostProcessor
*/
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;
}
過程:
先來看下有多少實現類
spring自己的實現類,其實只有2個:ConfigurationWarningsPostProcessor和ConfigurationClassPostProcessor,而且ConfigurationWarningsPostProcessor只是用來打印warning信息,因此主要來看下這個ConfigurationClassPostProcessor
而ConfigurationClassPostProcessor就是負責定義加載了
ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry
ConfigurationClassPostProcessor#processConfigBeanDefinitions
流程總結爲:
- 取出當前所有已註冊的bean定義:SpringApplication#createApplicationContext創建時註冊的註解相關的PostProcessor,源定義,還有ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry註冊的2個PostProcessors
- 從已註冊的bean定義中取出配置類型的bean定義,就是包含有以下註解的:@Configuration,@Component,@ComponentScan,@Import,@ImportResource
- 排序
- 解析這些配置bean,會根據@Conditional條件判斷是否跳過,根據配置信息取出所有需要加載的bean,例如:配置bean上有@ComponentScan註解,他就會去取出指定包下的所有bean;有@ImportResource註解,就會去讀對應的配置文件取出裏面配置的bean(詳細過程後面下面再講)
- 校驗:Configuration不能有子類,@Bean註解的方法不能重載
- 加載4中取出的bean的定義
- 再從新加載的這批bean定義中篩選出還沒有解析的配置類型的bean,然後在重複4,5,6的動作,直至所有配置類型的bean都被解析
- 最後,把parser.getImportRegistry()註冊上去,不是很瞭解這個是啥
至此,BeanDefinitionRegistryPostProcessor調用已經完成
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<BeanDefinitionHolder>();
// 取出所有已註冊的bean定義
String[] candidateNames = registry.getBeanDefinitionNames();
// 篩選出配置類型的bean定義
for (String beanName : candidateNames) {
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
// 如果這兩個字段已被設置,證明這個bean定義已被處理過
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
// 判斷依據:是否包含有以下註解的:@Configuration,@Component,@ComponentScan,@Import,@ImportResource
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// Return immediately if no @Configuration classes were found
if (configCandidates.isEmpty()) {
return;
}
// Sort by previously determined @Order value, if applicable
Collections.sort(configCandidates, new Comparator<BeanDefinitionHolder>() {
@Override
public int compare(BeanDefinitionHolder bd1, BeanDefinitionHolder bd2) {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return (i1 < i2) ? -1 : (i1 > i2) ? 1 : 0;
}
});
// Detect any custom bean name generation strategy supplied through the enclosing application context
// bean名字生成器選擇
SingletonBeanRegistry singletonRegistry = null;
if (registry instanceof SingletonBeanRegistry) {
singletonRegistry = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet && singletonRegistry.containsSingleton(CONFIGURATION_BEAN_NAME_GENERATOR)) {
BeanNameGenerator generator = (BeanNameGenerator) singletonRegistry.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
// Parse each @Configuration class
// 構建配置bean的解析器
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<BeanDefinitionHolder>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<ConfigurationClass>(configCandidates.size());
do {
// 根據配置信息取出所有需要加載的bean
parser.parse(candidates);
// 校驗:Configuration不能有子類,@Bean註解的方法不能重載
parser.validate();
Set<ConfigurationClass> configClasses = new LinkedHashSet<ConfigurationClass>(parser.getConfigurationClasses());
configClasses.removeAll(alreadyParsed);
// Read the model and create bean definitions based on its content
if (this.reader == null) {
this.reader = new ConfigurationClassBeanDefinitionReader(
registry, this.sourceExtractor, this.resourceLoader, this.environment,
this.importBeanNameGenerator, parser.getImportRegistry());
}
// 加載bean定義
this.reader.loadBeanDefinitions(configClasses);
alreadyParsed.addAll(configClasses);
candidates.clear();
// 從新加載的bean中找出配置類
if (registry.getBeanDefinitionCount() > candidateNames.length) {
String[] newCandidateNames = registry.getBeanDefinitionNames();
Set<String> oldCandidateNames = new HashSet<String>(Arrays.asList(candidateNames));
Set<String> alreadyParsedClasses = new HashSet<String>();
for (ConfigurationClass configurationClass : alreadyParsed) {
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
if (!oldCandidateNames.contains(candidateName)) {
BeanDefinition beanDef = registry.getBeanDefinition(candidateName);
if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(beanDef.getBeanClassName())) {
candidates.add(new BeanDefinitionHolder(beanDef, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
while (!candidates.isEmpty());
// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
if (singletonRegistry != null) {
if (!singletonRegistry.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
singletonRegistry.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
}
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
}
}
配置類的解析:
ConfigurationClassParser#parse
ConfigurationClassParser#processConfigurationClass
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
// 根據@Conditional註解條件,決定是否需要加載
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
ConfigurationClass existingClass = this.configurationClasses.get(configClass);
// 判斷是否被引入過
if (existingClass != null) {
if (configClass.isImported()) {
if (existingClass.isImported()) {
existingClass.mergeImportedBy(configClass);
}
// Otherwise ignore new imported config class; existing non-imported class overrides it.
return;
}
else {
// Explicit bean definition found, probably replacing an import.
// Let's remove the old one and go with the new one.
this.configurationClasses.remove(configClass);
for (Iterator<ConfigurationClass> it = this.knownSuperclasses.values().iterator(); it.hasNext(); ) {
if (configClass.equals(it.next())) {
it.remove();
}
}
}
}
// Recursively process the configuration class and its superclass hierarchy.
// 包裝成SourceClass
SourceClass sourceClass = asSourceClass(configClass);
do {
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
this.configurationClasses.put(configClass, configClass);
}
ConfigurationClassParser#doProcessConfigurationClass
主要解析的部分,流程可以分爲:
- 檢查是否存在內部類也是配置類,存在則回到上個調用方法開始解析
- 處理@PropertySource註解
- 處理@ComponentScan
- 處理@Import
- 處理@ImportResource
- @Bean的方法
- 處理接口上帶有@Bean註解的方法
- 處理父類,從1開始一遍
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass) throws IOException {
// Recursively process any member (nested) classes first
// 檢查是否存在內部類也是配置類,存在則回到上個調用方法開始解析
processMemberClasses(configClass, sourceClass);
// Process any @PropertySource annotations
for (AnnotationAttributes propertySource : AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), PropertySources.class, org.springframework.context.annotation.PropertySource.class)) {
if (this.environment instanceof ConfigurableEnvironment) {
processPropertySource(propertySource);
}
else {
logger.warn("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() +
"]. Reason: Environment must implement ConfigurableEnvironment");
}
}
// Process any @ComponentScan annotations
Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() && !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
for (AnnotationAttributes componentScan : componentScans) {
// The config class is annotated with @ComponentScan -> perform the scan immediately
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
// Check the set of scanned definitions for any further config classes and parse recursively if necessary
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
if (ConfigurationClassUtils.checkConfigurationClassCandidate(holder.getBeanDefinition(), this.metadataReaderFactory)) {
parse(holder.getBeanDefinition().getBeanClassName(), holder.getBeanName());
}
}
}
}
// Process any @Import annotations
processImports(configClass, sourceClass, getImports(sourceClass), true);
// Process any @ImportResource annotations
if (sourceClass.getMetadata().isAnnotated(ImportResource.class.getName())) {
AnnotationAttributes importResource =
AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
String[] resources = importResource.getStringArray("locations");
Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
for (String resource : resources) {
String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
configClass.addImportedResource(resolvedResource, readerClass);
}
}
// Process individual @Bean methods
Set<MethodMetadata> beanMethods = sourceClass.getMetadata().getAnnotatedMethods(Bean.class.getName());
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
// Process default methods on interfaces
processInterfaces(configClass, sourceClass);
// Process superclass, if any
if (sourceClass.getMetadata().hasSuperClass()) {
String superclass = sourceClass.getMetadata().getSuperClassName();
if (!superclass.startsWith("java") && !this.knownSuperclasses.containsKey(superclass)) {
this.knownSuperclasses.put(superclass, configClass);
// Superclass found, return its annotation metadata and recurse
return sourceClass.getSuperClass();
}
}
// No superclass -> processing is complete
return null;
}
BeanFactoryPostProcessor:
先看下注釋,主要有兩個功能:
- 修改bean定義:目前來看主要是其子類BeanDefinitionRegistryPostProcessor完成了這個功能
- 修改bean屬性:通過讀取配置文件修改屬性值,然後提到了PropertyResourceConfigurer這個類,專門用於解決這個配置的問題
最後說到了注意事項,只能操作bean定義,但是不準實例化對象,否則會導致意外的問題
定義在前面的時候已經加載了,這邊基本是對屬性值的一個修改
/**
* Allows for custom modification of an application context's bean definitions,
* adapting the bean property values of the context's underlying bean factory.
*
* <p>Application contexts can auto-detect BeanFactoryPostProcessor beans in
* their bean definitions and apply them before any other beans get created.
*
* <p>Useful for custom config files targeted at system administrators that
* override bean properties configured in the application context.
*
* <p>See PropertyResourceConfigurer and its concrete implementations
* for out-of-the-box solutions that address such configuration needs.
*
* <p>A BeanFactoryPostProcessor may interact with and modify bean
* definitions, but never bean instances. Doing so may cause premature bean
* instantiation, violating the container and causing unintended side-effects.
* If bean instance interaction is required, consider implementing
* {@link BeanPostProcessor} instead.
*
* @author Juergen Hoeller
* @since 06.07.2003
* @see BeanPostProcessor
* @see PropertyResourceConfigurer
*/
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;
}
註冊BeanPostProcessor
PostProcessorRegistrationDelegate#registerBeanPostProcessors
這塊其實跟上面調用BeanFactoryPostProcessor類似,也是通過beanFactory#getBeanNamesForType方法查出所有BeanPostProcessor對象,然後分成3組:a.實現了PriorityOrdered接口的 b.實現了Ordered接口 c.其他。不同的是上面的是直接調用,這裏是添加到beanFactory的BeanPostProcessor列表裏面,供後續調用
構建bean
總流程:
- 如果是單例模式先查緩存,緩存有就返回
- 判斷是不是正在構建的Prototype bean,是就直接報異常
- 如果父BeanFactory不爲空,並且沒有bean定義,則調用父BeanFactory獲取bean
- 標記bean已經構建
- 檢查bean是否abstract類,是直接報錯
- 如果有@DependsOn,先構建被依賴的bean,並且記錄依賴關係
- 根據scope分3種情況執行
7.1 單例模式的構建
7.1.1. 處理@Lookup註解
7.1.2. 調用InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation
7.1.3. 通過構造函數創建對象
7.1.4. 調用MergedBeanDefinitionPostProcessor#postProcessMergedBeanDefinition接口
7.1.5. 初始化bean屬性:調用InstantiationAwareBeanPostProcessor#postProcessAfterInstantiation方法,給@Autowired屬性注入對象,調用InstantiationAwareBeanPostProcessor#postProcessPropertyValues方法
7.1.6. 初始化bean:調用BeanPostProcessor#postProcessBeforeInitialization方法,調用afterPropertiesSet方法或者指定的init method,執行BeanPostProcessor#postProcessAfterInitialization方法
7.2 原型模式的構建
7.3 其他構建 - 如果需要類型轉換的則進行轉換
AbstractApplicationContext#finishBeanFactoryInitialization
DefaultListableBeanFactory#preInstantiateSingletons
@Override
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Pre-instantiating singletons in " + this);
}
// Iterate over a copy to allow for init methods which in turn register new bean definitions.
// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
// 前面加載的bean定義
List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans...
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
// 不是虛類 and 是單例模式 and 不是延遲加載
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
if (isFactoryBean(beanName)) {
// 如果實現了FactoryBean接口,再判斷是否是現在就構建
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 {
// 非FactoryBean直接構建
getBean(beanName);
}
}
}
// Trigger post-initialization callback for all applicable beans...
// 如果實現了SmartInitializingSingleton接口,調用它的afterSingletonsInstantiated方法
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
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();
}
}
}
}
下面來看具體的構建過程
AbstractBeanFactory#getBean
AbstractBeanFactory#doGetBean
不同模式構建其實都一樣,都是調用AbstractAutowireCapableBeanFactory#createBean構建,只是觸發的接口調用不同
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;
// Eagerly check singleton cache for manually registered singletons.
// 單例模式會先從緩存取
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 {
// Fail if we're already creating this bean instance:
// We're assumably within a circular reference.
// 判斷是不是正在構建的Prototype bean
if (isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// Check if bean definition exists in this factory.
// 如果查不到bean定義,調用父BeanFactory去獲取bean
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);
}
}
// 如果是要構建bean的,把bean標誌已經創建(加入到alreadyCreated)
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
try {
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
// Guarantee initialization of beans that the current bean depends on.
// 如果有@DependsOn註解,先構建依賴的bean
String[] dependsOn = mbd.getDependsOn();
if (dependsOn != null) {
for (String dependsOnBean : dependsOn) {
// 如果有循環依賴,直接報錯
if (isDependent(beanName, dependsOnBean)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dependsOnBean + "'");
}
// 標記下這個bean依賴了哪些bean,後續銷燬的時候,先銷燬依賴方
registerDependentBean(dependsOnBean, beanName);
// 構建bean
getBean(dependsOnBean);
}
}
// Create bean instance.
// 根據scope,分3中情況執行
if (mbd.isSingleton()) {
// 單例模式
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()) {
// prototype模式
// 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 {
// 其他模式
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;
}
下面就看下單例模式爲例
DefaultSingletonBeanRegistry#getSingleton
AbstractAutowireCapableBeanFactory#createBean
protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException {
if (logger.isDebugEnabled()) {
logger.debug("Creating instance of bean '" + beanName + "'");
}
RootBeanDefinition mbdToUse = mbd;
// Make sure bean class is actually resolved at this point, and
// clone the bean definition in case of a dynamically resolved Class
// which cannot be stored in the shared merged bean definition.
// 獲取bean類型,並複製bean定義,
Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
mbdToUse = new RootBeanDefinition(mbd);
mbdToUse.setBeanClass(resolvedClass);
}
// Prepare method overrides.
// 處理有方法添加了@Lookup註解的類
try {
mbdToUse.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
// 調用InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation,和#postProcessAfterInitialization(前面返回不爲空的話)
// 看了下,還沒有實現類來通過這個接口返回對象的,因爲到這,bean還沒初始化,如果這裏創建代理的話,要做的事情太多
try {
// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
Object beanInstance = doCreateBean(beanName, mbdToUse, args);
if (logger.isDebugEnabled()) {
logger.debug("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}
AbstractAutowireCapableBeanFactory#doCreateBean
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
// Instantiate the bean.
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
// 創建bean對象,只是調用了構造函數
if (instanceWrapper == null) {
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
// Allow post-processors to modify the merged bean definition.
// 調用MergedBeanDefinitionPostProcessor接口
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
mbd.postProcessed = true;
}
}
// Eagerly cache singletons to be able to resolve circular references
// even when triggered by lifecycle interfaces like BeanFactoryAware.
boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
isSingletonCurrentlyInCreation(beanName));
if (earlySingletonExposure) {
if (logger.isDebugEnabled()) {
logger.debug("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
addSingletonFactory(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
return getEarlyBeanReference(beanName, mbd, bean);
}
});
}
// Initialize the bean instance.
Object exposedObject = bean;
try {
// 初始化bean屬性
populateBean(beanName, mbd, instanceWrapper);
if (exposedObject != null) {
// 初始化bean
exposedObject = initializeBean(beanName, exposedObject, mbd);
}
}
catch (Throwable ex) {
if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
throw (BeanCreationException) ex;
}
else {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
}
}
if (earlySingletonExposure) {
Object earlySingletonReference = getSingleton(beanName, false);
if (earlySingletonReference != null) {
if (exposedObject == bean) {
exposedObject = earlySingletonReference;
}
else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
String[] dependentBeans = getDependentBeans(beanName);
Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length);
for (String dependentBean : dependentBeans) {
if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
actualDependentBeans.add(dependentBean);
}
}
if (!actualDependentBeans.isEmpty()) {
throw new BeanCurrentlyInCreationException(beanName,
"Bean with name '" + beanName + "' has been injected into other beans [" +
StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
"] in its raw version as part of a circular reference, but has eventually been " +
"wrapped. This means that said other beans do not use the final version of the " +
"bean. This is often the result of over-eager type matching - consider using " +
"'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
// 註冊銷燬方法
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
主要看下bean的初始化那塊吧:
初始化bean的屬性
AbstractAutowireCapableBeanFactory#populateBean
protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
PropertyValues pvs = mbd.getPropertyValues();
if (bw == null) {
if (!pvs.isEmpty()) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
}
else {
// Skip property population phase for null instance.
return;
}
}
// Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
// state of the bean before properties are set. This can be used, for example,
// to support styles of field injection.
boolean continueWithPropertyPopulation = true;
// 調用InstantiationAwareBeanPostProcessor#postProcessAfterInstantiation方法
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
continueWithPropertyPopulation = false;
break;
}
}
}
}
if (!continueWithPropertyPopulation) {
return;
}
// 給@Autowired屬性,注入對象,也是通過這個構造流程來構建bean並注入
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
// Add property values based on autowire by name if applicable.
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
// Add property values based on autowire by type if applicable.
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
// 調用InstantiationAwareBeanPostProcessor#postProcessPropertyValues方法
if (hasInstAwareBpps || needsDepCheck) {
PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
if (hasInstAwareBpps) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvs == null) {
return;
}
}
}
}
if (needsDepCheck) {
checkDependencies(beanName, mbd, filteredPds, pvs);
}
}
applyPropertyValues(beanName, mbd, bw, pvs);
}
初始化bean
AbstractAutowireCapableBeanFactory#initializeBean
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
invokeAwareMethods(beanName, bean);
return null;
}
}, getAccessControlContext());
}
else {
invokeAwareMethods(beanName, bean);
}
// 調用BeanPostProcessor#postProcessBeforeInitialization方法
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
// 如果bean實現了InitializingBean接口則執行afterPropertiesSet方法,或者如果指定了init mehod,執行該init method
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
// 執行BeanPostProcessor#postProcessAfterInitialization方法
// 一般做代理類的,通常會在這一部進行代理類的替換
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}