每次進入原始碼的世界，就像完成一場奇妙的旅行！
1. 屬性賦值概述
上一篇講述了bean例項化中的建立例項過程，例項化後就需要對類中的屬性進行依賴注入操作，本篇將重點分析屬性賦值相關流程。其中屬性賦值，體現在AbstractAutowireCapableBeanFactory類中的doCreateBean方法中的populateBean(beanName, mbd, instanceWrapper)這行程式碼；在賦值之前還做了收集屬性的相關操作，下面就通過原始碼來分析。
2. 流程概覽
流程中分為三步：
step1:通過BeanPostProcessor的實現類，實現了帶註解的屬性收集，CommonAnnotationBeanPostProcessor 支援了@PostContructor、@PreDestroy、@Resource的收集；AutowiredAnnotationBeanPostProcessor支援@Autowired、@value註解的屬性收集；
step2:將收集有註解屬性和方法封裝到對應的容器中；
step3:遍歷容器中的屬性，注入到對應的bean例項中。
3. 原始碼分析
3.1 收集@PostConstruct @PreDestroy註解的方法
首先AbstractAutowireCapableBeanFactory類中的doCreateBean`方法：
protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
throws BeanCreationException {
// Instantiate the bean.
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
//建立物件例項
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
Object bean = instanceWrapper.getWrappedInstance();
Class<?> beanType = instanceWrapper.getWrappedClass();
if (beanType != NullBean.class) {
mbd.resolvedTargetType = beanType;
}
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
try {
// 收集註解
// BeanPostProcessor典型應用
// CommonAnnotationBeanPostProcessor 支援了@PostContructor @PreDestroy @Resource
// AutowiredAnnotationBeanPostProcessor 支援@Autowired @value 註解
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Post-processing of merged bean definition failed", ex);
}
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.isTraceEnabled()) {
logger.trace("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
}
// Initialize the bean instance.
Object exposedObject = bean;
try {
// 屬性賦值
populateBean(beanName, mbd, instanceWrapper);
// 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<>(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 " +
"'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
createBeanInstance上一篇已經講完，完成bean的建立，建立完後，bean只是在堆記憶體中申請了一塊記憶體空間，還沒有對其屬性賦值，而在屬性賦值前，優先收集標註了註解的屬性，收集過程在applyMergedBeanDefinitionPostProcessors方法中完成，進入該方法：
protected void applyMergedBeanDefinitionPostProcessors(RootBeanDefinition mbd, Class<?> beanType, String beanName) {
// 遍歷當前類中的所有BeanPostProcessors
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof MergedBeanDefinitionPostProcessor) {
MergedBeanDefinitionPostProcessor bdp = (MergedBeanDefinitionPostProcessor) bp;
bdp.postProcessMergedBeanDefinition(mbd, beanType, beanName);
}
}
}
遍歷當前類中的實現了BeanPostProcessor介面的類，再次進入postProcessMergedBeanDefinition方法，會看到有幾個典型的實現類，首先是 CommonAnnotationBeanPostProcessor類，這個類完成了@Resource註解的屬性或者方法的收集，這個類還對@PostConstruct和@PreDestory支援。具體的收集過程如下：
public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
// 掃描@PostConstructor @PreDestroy
super.postProcessMergedBeanDefinition(beanDefinition, beanType, beanName);
// 掃描屬性與方法上的@Resource註解，收集到InjectionMetadata容器中
InjectionMetadata metadata = findResourceMetadata(beanName, beanType, null);
metadata.checkConfigMembers(beanDefinition);
}
回到CommonAnnotationBeanPostProcessor類的構造方法，完成@PostConstruct和@PreDestory註解的設值，分別塞到initAnnotationType與destroyAnnotationType屬性中：
public CommonAnnotationBeanPostProcessor() {
setOrder(Ordered.LOWEST_PRECEDENCE - 3);
setInitAnnotationType(PostConstruct.class);
setDestroyAnnotationType(PreDestroy.class);
ignoreResourceType("javax.xml.ws.WebServiceContext");
}
點選進入其父類InitDestroyAnnotationBeanPostProcessor的postProcessMergedBeanDefinition方法
public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
LifecycleMetadata metadata = findLifecycleMetadata(beanType);
metadata.checkConfigMembers(beanDefinition);
}
點選findLifecycleMetadata進入方法：
private LifecycleMetadata findLifecycleMetadata(Class<?> clazz) {
if (this.lifecycleMetadataCache == null) {
// Happens after deserialization, during destruction...
return buildLifecycleMetadata(clazz);
}
// Quick check on the concurrent map first, with minimal locking.
LifecycleMetadata metadata = this.lifecycleMetadataCache.get(clazz);
if (metadata == null) {
synchronized (this.lifecycleMetadataCache) {
metadata = this.lifecycleMetadataCache.get(clazz);
if (metadata == null) {
// 構建生命週期相關的後設資料
metadata = buildLifecycleMetadata(clazz);
this.lifecycleMetadataCache.put(clazz, metadata);
}
return metadata;
}
}
return metadata;
}
再次進入構建生命週期相關的後設資料的方法buildLifecycleMetadata:
private LifecycleMetadata buildLifecycleMetadata(final Class<?> clazz) {
if (!AnnotationUtils.isCandidateClass(clazz, Arrays.asList(this.initAnnotationType, this.destroyAnnotationType))) {
return this.emptyLifecycleMetadata;
}
List<LifecycleElement> initMethods = new ArrayList<>();
List<LifecycleElement> destroyMethods = new ArrayList<>();
Class<?> targetClass = clazz;
do {
final List<LifecycleElement> currInitMethods = new ArrayList<>();
final List<LifecycleElement> currDestroyMethods = new ArrayList<>();
//遍歷類中的方法，找到@PostConstruct註解的方法
ReflectionUtils.doWithLocalMethods(targetClass, method -> {
if (this.initAnnotationType != null && method.isAnnotationPresent(this.initAnnotationType)) {
LifecycleElement element = new LifecycleElement(method);
currInitMethods.add(element);
if (logger.isTraceEnabled()) {
logger.trace("Found init method on class [" + clazz.getName() + "]: " + method);
}
}
//遍歷類中的方法，找到@PreDestroy註解的方法
if (this.destroyAnnotationType != null && method.isAnnotationPresent(this.destroyAnnotationType)) {
currDestroyMethods.add(new LifecycleElement(method));
if (logger.isTraceEnabled()) {
logger.trace("Found destroy method on class [" + clazz.getName() + "]: " + method);
}
}
});
// @PostConstruct註解的方法加到initMethods
initMethods.addAll(0, currInitMethods);
// @PreDestroy註解的方法加到destroyMethods
destroyMethods.addAll(currDestroyMethods);
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
return (initMethods.isEmpty() && destroyMethods.isEmpty() ? this.emptyLifecycleMetadata :
new LifecycleMetadata(clazz, initMethods, destroyMethods));
}
迴圈遍歷類中的所有的方法，判斷方法上是否有@PostConstruct註解如果有的話加入到initMethods集合，判斷方法上是否有@PreDestroy註解，如果有加入到destroyMethods集合中去。
3.2 收集@Resource註解的屬性與方法
進入上述findResourceMetadata方法：
private InjectionMetadata findResourceMetadata(String beanName, final Class<?> clazz, @Nullable PropertyValues pvs) {
// Fall back to class name as cache key, for backwards compatibility with custom callers.
String cacheKey = (StringUtils.hasLength(beanName) ? beanName : clazz.getName());
// 檢視快取裡面有沒有InjectionMetadata例項.
InjectionMetadata metadata = this.injectionMetadataCache.get(cacheKey);
if (InjectionMetadata.needsRefresh(metadata, clazz)) {
synchronized (this.injectionMetadataCache) {
metadata = this.injectionMetadataCache.get(cacheKey);
if (InjectionMetadata.needsRefresh(metadata, clazz)) {
if (metadata != null) {
metadata.clear(pvs);
}
// 構建@Resource後設資料
metadata = buildResourceMetadata(clazz);
this.injectionMetadataCache.put(cacheKey, metadata);
}
}
}
return metadata;
}
step1:看快取裡面有沒有 InjectionMetadata 物件；
step2:構建@Resource後設資料；
再次進入buildResourceMetadata方法：
private InjectionMetadata buildResourceMetadata(final Class<?> clazz) {
if (!AnnotationUtils.isCandidateClass(clazz, resourceAnnotationTypes)) {
return InjectionMetadata.EMPTY;
}
List<InjectionMetadata.InjectedElement> elements = new ArrayList<>();
Class<?> targetClass = clazz;
do {
final List<InjectionMetadata.InjectedElement> currElements = new ArrayList<>();
// 遍歷所有field，判斷有沒有Resource註解
ReflectionUtils.doWithLocalFields(targetClass, field -> {
if (webServiceRefClass != null && field.isAnnotationPresent(webServiceRefClass)) {
if (Modifier.isStatic(field.getModifiers())) {
throw new IllegalStateException("@WebServiceRef annotation is not supported on static fields");
}
currElements.add(new WebServiceRefElement(field, field, null));
}
else if (ejbClass != null && field.isAnnotationPresent(ejbClass)) {
if (Modifier.isStatic(field.getModifiers())) {
throw new IllegalStateException("@EJB annotation is not supported on static fields");
}
currElements.add(new EjbRefElement(field, field, null));
}
else if (field.isAnnotationPresent(Resource.class)) {
if (Modifier.isStatic(field.getModifiers())) {
throw new IllegalStateException("@Resource annotation is not supported on static fields");
}
if (!this.ignoredResourceTypes.contains(field.getType().getName())) {
currElements.add(new ResourceElement(field, field, null));
}
}
});
// 遍歷所有方法，判斷有沒有@Resource註解
ReflectionUtils.doWithLocalMethods(targetClass, method -> {
Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
if (!BridgeMethodResolver.isVisibilityBridgeMethodPair(method, bridgedMethod)) {
return;
}
if (method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
if (webServiceRefClass != null && bridgedMethod.isAnnotationPresent(webServiceRefClass)) {
if (Modifier.isStatic(method.getModifiers())) {
throw new IllegalStateException("@WebServiceRef annotation is not supported on static methods");
}
if (method.getParameterCount() != 1) {
throw new IllegalStateException("@WebServiceRef annotation requires a single-arg method: " + method);
}
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new WebServiceRefElement(method, bridgedMethod, pd));
}
else if (ejbClass != null && bridgedMethod.isAnnotationPresent(ejbClass)) {
if (Modifier.isStatic(method.getModifiers())) {
throw new IllegalStateException("@EJB annotation is not supported on static methods");
}
if (method.getParameterCount() != 1) {
throw new IllegalStateException("@EJB annotation requires a single-arg method: " + method);
}
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new EjbRefElement(method, bridgedMethod, pd));
}
else if (bridgedMethod.isAnnotationPresent(Resource.class)) {
if (Modifier.isStatic(method.getModifiers())) {
throw new IllegalStateException("@Resource annotation is not supported on static methods");
}
Class<?>[] paramTypes = method.getParameterTypes();
if (paramTypes.length != 1) {
throw new IllegalStateException("@Resource annotation requires a single-arg method: " + method);
}
if (!this.ignoredResourceTypes.contains(paramTypes[0].getName())) {
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new ResourceElement(method, bridgedMethod, pd));
}
}
}
});
elements.addAll(0, currElements);
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
return InjectionMetadata.forElements(elements, clazz);
}
step1:從類中獲取所有 Field 物件，迴圈 field 物件，判斷 field 有沒有@Resource 註解，如果有註解封裝成 ResourceElement 物件；
step2:從類中獲取所有 Method物件，迴圈 Method物件，判斷 Method有沒有@Resource 註解，如果有註解封裝成 ResourceElement 物件；
step3:最終把兩個 field 和 Method 封裝的物件集合封裝到 InjectionMetadata 物件中。
3.3 @Autowired註解的屬性與方法收集
AutowiredAnnotationBeanPostProcessor類對@Autowired和@Value註解的屬性和方法的收集，收集支援的註解型別可以在建構函式或者 Static 靜態塊中找。收集過程基本上跟@Resource註解的收集差不多。下面先看AutowiredAnnotationBeanPostProcessor的建構函式：
public AutowiredAnnotationBeanPostProcessor() {
this.autowiredAnnotationTypes.add(Autowired.class);
this.autowiredAnnotationTypes.add(Value.class);
try {
this.autowiredAnnotationTypes.add((Class<? extends Annotation>)
ClassUtils.forName("javax.inject.Inject", AutowiredAnnotationBeanPostProcessor.class.getClassLoader()));
logger.trace("JSR-330 'javax.inject.Inject' annotation found and supported for autowiring");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
收集了@Autowired和@Value註解並設定到autowiredAnnotationTypes型別中。後面流程與@Resource收集一樣，也是收集Field和Method上面的註解，然後放到InjectionMetadata物件中。
private InjectionMetadata buildAutowiringMetadata(final Class<?> clazz) {
if (!AnnotationUtils.isCandidateClass(clazz, this.autowiredAnnotationTypes)) {
return InjectionMetadata.EMPTY;
}
List<InjectionMetadata.InjectedElement> elements = new ArrayList<>();
Class<?> targetClass = clazz;
do {
final List<InjectionMetadata.InjectedElement> currElements = new ArrayList<>();
// 迴圈收集Field上面是否有@Autowired註解
ReflectionUtils.doWithLocalFields(targetClass, field -> {
MergedAnnotation<?> ann = findAutowiredAnnotation(field);
if (ann != null) {
if (Modifier.isStatic(field.getModifiers())) {
if (logger.isInfoEnabled()) {
logger.info("Autowired annotation is not supported on static fields: " + field);
}
return;
}
boolean required = determineRequiredStatus(ann);
currElements.add(new AutowiredFieldElement(field, required));
}
});
// 迴圈收集Method上面是否有@Autowired註解
ReflectionUtils.doWithLocalMethods(targetClass, method -> {
Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
if (!BridgeMethodResolver.isVisibilityBridgeMethodPair(method, bridgedMethod)) {
return;
}
MergedAnnotation<?> ann = findAutowiredAnnotation(bridgedMethod);
if (ann != null && method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
if (Modifier.isStatic(method.getModifiers())) {
if (logger.isInfoEnabled()) {
logger.info("Autowired annotation is not supported on static methods: " + method);
}
return;
}
if (method.getParameterCount() == 0) {
if (logger.isInfoEnabled()) {
logger.info("Autowired annotation should only be used on methods with parameters: " +
method);
}
}
boolean required = determineRequiredStatus(ann);
PropertyDescriptor pd = BeanUtils.findPropertyForMethod(bridgedMethod, clazz);
currElements.add(new AutowiredMethodElement(method, required, pd));
}
});
// 放入容器elements，而elements本身是InjectionMetadata型別下的InjectedElement屬性
elements.addAll(0, currElements);
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
return InjectionMetadata.forElements(elements, clazz);
}
3.4 屬性賦值
收集完@Resource和@Autowired註解以後就開始依賴注入，進入populateBean方法：
protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
if (bw == null) {
if (mbd.hasPropertyValues()) {
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.
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
return;
}
}
}
}
PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);
int resolvedAutowireMode = mbd.getResolvedAutowireMode();
if (resolvedAutowireMode == AUTOWIRE_BY_NAME || resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
// Add property values based on autowire by name if applicable.
if (resolvedAutowireMode == AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
// Add property values based on autowire by type if applicable.
if (resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE);
PropertyDescriptor[] filteredPds = null;
if (hasInstAwareBpps) {
if (pvs == null) {
pvs = mbd.getPropertyValues();
}
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
// 依賴注入的過程，@Autowired支援 @Resource支援
PropertyValues pvsToUse = ibp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
if (pvsToUse == null) {
if (filteredPds == null) {
filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
}
pvsToUse = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvsToUse == null) {
return;
}
}
pvs = pvsToUse;
}
}
}
if (needsDepCheck) {
if (filteredPds == null) {
filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
}
checkDependencies(beanName, mbd, filteredPds, pvs);
}
if (pvs != null) {
applyPropertyValues(beanName, mbd, bw, pvs);
}
}
該方法的核心工作就是完成依賴注入，進入postProcessProperties方法：
public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) {
InjectionMetadata metadata = findAutowiringMetadata(beanName, bean.getClass(), pvs);
try {
// 依賴注入
metadata.inject(bean, beanName, pvs);
}
catch (BeanCreationException ex) {
throw ex;
}
catch (Throwable ex) {
throw new BeanCreationException(beanName, "Injection of autowired dependencies failed", ex);
}
return pvs;
}
最後通過metadata.inject方法把容器中收集的屬性注入：
public void inject(Object target, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
Collection<InjectedElement> checkedElements = this.checkedElements;
Collection<InjectedElement> elementsToIterate =
(checkedElements != null ? checkedElements : this.injectedElements);
if (!elementsToIterate.isEmpty()) {
for (InjectedElement element : elementsToIterate) {
if (logger.isTraceEnabled()) {
logger.trace("Processing injected element of bean '" + beanName + "': " + element);
}
// 迴圈呼叫每個方法依賴一次處理
element.inject(target, beanName, pvs);
}
}
}
點選進入inject方法：
protected void inject(Object target, @Nullable String requestingBeanName, @Nullable PropertyValues pvs)
throws Throwable {
if (this.isField) {
Field field = (Field) this.member;
ReflectionUtils.makeAccessible(field);
// 設定屬性,getResourceToInject會觸發getBean
field.set(target, getResourceToInject(target, requestingBeanName));
}
else {
if (checkPropertySkipping(pvs)) {
return;
}
try {
Method method = (Method) this.member;
ReflectionUtils.makeAccessible(method);
// 設定方法
method.invoke(target, getResourceToInject(target, requestingBeanName));
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
看到屬性與方法通過反射的注入到所需的例項中，如果注入的是引用型別，會通過呼叫getResourceToInject方法優先拿到引用型別的例項，底層是通過BeanFactory.getBean方式拿到應用的屬性的:
protected Object getResourceToInject(Object target, @Nullable String requestingBeanName) {
if (StringUtils.hasLength(this.beanName)) {
if (beanFactory != null && beanFactory.containsBean(this.beanName)) {
// Local match found for explicitly specified local bean name.
// 通過getBean方式拿引用型別的值
Object bean = beanFactory.getBean(this.beanName, this.lookupType);
if (requestingBeanName != null && beanFactory instanceof ConfigurableBeanFactory) {
((ConfigurableBeanFactory) beanFactory).registerDependentBean(this.beanName, requestingBeanName);
}
return bean;
}
else if (this.isDefaultName && !StringUtils.hasLength(this.mappedName)) {
throw new NoSuchBeanDefinitionException(this.beanName,
"Cannot resolve 'beanName' in local BeanFactory. Consider specifying a general 'name' value instead.");
}
}
4. 總結
本篇講述了例項化後屬性的收集與賦值過程，通過典型的BeanPostProccessor應用，完成相關注解的收集，並完成依賴注入，最終完成屬性賦值，後續將繼續分析初始化流程。