引言
上期分析了
refresh方法中大部分，這期我們只分析finishBeanFactoryInitialization(beanFactory)這一個方法，分析這個方法的過程中我們會順藤摸瓜把bean初始化的整個流程都分析一遍
finishBeanFactoryInitialization(beanFactory)
提前初始化一些非延遲加載的單例類型的bean，這里主要看最后一行 beanFactory.preInstantiateSingletons(),這里是初始化非延遲加載單例的入口
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// 初始化類型轉(zhuǎn)化的bean
if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
beanFactory.setConversionService(
beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
}
// Register a default embedded value resolver if no bean post-processor
// (such as a PropertyPlaceholderConfigurer bean) registered any before:
// at this point, primarily for resolution in annotation attribute values.
// 注冊默認的值解析器
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(new StringValueResolver() {
@Override
public String resolveStringValue(String strVal) {
return getEnvironment().resolvePlaceholders(strVal);
}
});
}
// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// Stop using the temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(null);
// Allow for caching all bean definition metadata, not expecting further changes.
beanFactory.freezeConfiguration();
// Instantiate all remaining (non-lazy-init) singletons.
beanFactory.preInstantiateSingletons();
}
preInstantiateSingletons
方法在DefaultListableBeanFactory中，用于初始化所有非延遲加載的單例
public void preInstantiateSingletons() throws BeansException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Pre-instantiating singletons in " + this);
}
// 所有注冊完成的 beanDefinitionNames
List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
// 遍歷所有非延遲加載的單例類型
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
// 判斷類型是否為 FactoryBean
if (isFactoryBean(beanName)) {
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());
}
// 是否需要立即加載
if (isEagerInit) {
getBean(beanName);
}
}
else {
getBean(beanName);
}
}
}
// Trigger post-initialization callback for all applicable beans...
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();
}
}
}
}
可以看到這段代碼主要做了2個事情
- 判斷bean的類型是否是
factoryBean，如果是的話判斷類型是不是SmartFactoryBean，再獲取是否需要立即加載的isEagerInit屬性，執(zhí)行getBean方法 - 在單例
bean都初始化完成后，循環(huán)判斷bean的類型是否是SmartInitializingSingleton，是的話會在這時候執(zhí)行afterSingletonsInstantiated方法
接下來就是獲取bean的流程代碼
getBean
getBean方法最終都是走的doGetBean方法
public Object getBean(String name) throws BeansException {
return doGetBean(name, null, null, false);
}
doGetBean
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;
// 首先檢查緩存是否有，有則直接取
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 + "'");
}
}
// 這里是取FactoryBean
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
// 緩存里沒有 第一次初始化Bean
else {
// 判斷是不是處于循環(huán)依賴當中，有則直接報錯
if (isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// 檢查父容器是否存在此Bean的定義
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// Not found -> check parent.
// 返回原始的名稱 加上FactoryBean符號
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);
}
}
if (!typeCheckOnly) {
// 把Bean的狀態(tài)改為已創(chuàng)建，并從mergedBeanDefinitions 中移除
markBeanAsCreated(beanName);
}
try {
// 合并BeanDefinition轉(zhuǎn)化成RootBeanDefinition
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
// 獲取配置的 depends-On 依賴,優(yōu)先加載
String[] dependsOn = mbd.getDependsOn();
if (dependsOn != null) {
for (String dep : dependsOn) {
if (isDependent(beanName, dep)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
}
registerDependentBean(dep, beanName);
try {
// 遞歸獲取
getBean(dep);
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"'" + beanName + "' depends on missing bean '" + dep + "'", ex);
}
}
}
// Create bean instance.
// 如果是單例
if (mbd.isSingleton()) {
// 這里會把創(chuàng)建完成的bean加入緩存
sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
try {
// 創(chuàng)建bean的主邏輯
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);
}
// 判斷類型 prototype 有狀態(tài)的bean
else if (mbd.isPrototype()) {
// 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 {
// 其他類型的scope
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.
// 如果有指定的類型，則檢查是否與實際bean實例的類型匹配
if (requiredType != null && bean != null && !requiredType.isInstance(bean)) {
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;
}
看完上面的代碼，我們作總結(jié)：
首先，創(chuàng)建bean之前會檢查單例緩存里有沒有，有的話會直接返回。然后會檢查父容器是否有這個bean的定義，一直找到最頂層的父容器（有點類型雙親委派），最后會在父容器執(zhí)行這個bean的獲取，之后獲取depends-On如果有配置的話會優(yōu)先獲?。ㄟf歸獲取直到依賴的所有depends-On），最后才是根據(jù)scope調(diào)用AbstractAutowireCapableBeanFactory的createBean方法
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.
Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
mbdToUse = new RootBeanDefinition(mbd);
mbdToUse.setBeanClass(resolvedClass);
}
// Prepare method overrides.
try {
mbdToUse.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
try {
// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
// 擴展點，可以通過實現(xiàn)InstantiationAwareBeanPostProcessor 接口一個返回代理而不是目標bean實例
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;
}
這段代碼主要看一下resolveBeforeInstantiation(beanName, mbdToUse)，這里是spring提供的一個擴展點，可以通過實現(xiàn)InstantiationAwareBeanPostProcessor接口在這里返回bean的代理
然后就可以直接看最后的doCreateBean(beanName, mbdToUse, args)方法
doCreateBean
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
throws BeanCreationException {
// Instantiate the bean.
// 封裝bean的容器
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
// 這里是創(chuàng)建 BeanWrapper
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
mbd.resolvedTargetType = beanType;
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
try {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Post-processing of merged bean definition failed", ex);
}
mbd.postProcessed = true;
}
}
// 判斷是否需要提前暴露對象的引用，用于解決循環(huán)依賴
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 {
// 依賴注入的主邏輯
populateBean(beanName, mbd, instanceWrapper);
if (exposedObject != null) {
// 執(zhí)行一些初始化的方法
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.
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
這段代碼主要看這三個方法
-
createBeanInstance(beanName, mbd, args)創(chuàng)建bean -
populateBean(beanName, mbd, instanceWrapper)組裝bean的依賴 -
initializeBean(beanName, exposedObject, mbd)調(diào)用bean的一些初始化方法，以及擴展接口
接下來我們著重來看這三個方法
createBeanInstance
protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, Object[] args) {
// Make sure bean class is actually resolved at this point.
// 獲取bean class
Class<?> beanClass = resolveBeanClass(mbd, beanName);
// 不是 pullic 直接拋異常
if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Bean class isn't public, and non-public access not allowed: " + beanClass.getName());
}
// 使用工廠方法實例化bean
if (mbd.getFactoryMethodName() != null) {
return instantiateUsingFactoryMethod(beanName, mbd, args);
}
// Shortcut when re-creating the same bean...
// 判斷bean是否創(chuàng)建過
boolean resolved = false;
boolean autowireNecessary = false;
if (args == null) {
synchronized (mbd.constructorArgumentLock) {
if (mbd.resolvedConstructorOrFactoryMethod != null) {
resolved = true;
autowireNecessary = mbd.constructorArgumentsResolved;
}
}
}
// 如果已經(jīng)加載過
if (resolved) {
if (autowireNecessary) {
// 有參構(gòu)造方法
return autowireConstructor(beanName, mbd, null, null);
}
else {
// 使用無參構(gòu)造
return instantiateBean(beanName, mbd);
}
}
// Need to determine the constructor...
// 尋找一個合適的構(gòu)造方法
Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
if (ctors != null ||
mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_CONSTRUCTOR ||
mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {
return autowireConstructor(beanName, mbd, ctors, args);
}
// No special handling: simply use no-arg constructor.
return instantiateBean(beanName, mbd);
}
這個方法的主要邏輯其實就是在找一個合適的初始化方法
- 首先判斷
RootBeanDefinition是否含有factory-method配置，有的話使用工廠方法實例化bean - 之后的邏輯就是尋找一個合適的構(gòu)造方法用于bean的實例化
- 如果判斷是有參的構(gòu)造方法，則通過
autowireConstructor實例化，初始化的過程很繁瑣，其中對構(gòu)造方法參數(shù)的依賴也是通過遞歸getBean()來實現(xiàn)的 - 無參的則使用
instantiateBean實例化
- 如果判斷是有參的構(gòu)造方法，則通過
到這里執(zhí)行完bean已經(jīng)創(chuàng)建了(spring默認是使用CGLIB)，但是這時候的bean是不完整的，相關(guān)的依賴項還并沒有被注入
populateBean(beanName, mbd, instanceWrapper)
組裝bean的邏輯都在這里
protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
// 獲取的配置的property依賴
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;
}
}
// 擴展點 執(zhí)行實現(xiàn)了InstantiationAwareBeanPostProcessors接口方法
// 在設(shè)置屬性依賴之前可以有機會修改bean的屬性配置
boolean continueWithPropertyPopulation = true;
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;
}
}
}
}
// 判斷是否需要繼續(xù)組裝bean屬性
if (!continueWithPropertyPopulation) {
return;
}
// 判斷自動配的類型（按名稱和按類型）
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.
// 按bean的名稱注入
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
// Add property values based on autowire by type if applicable.
// 按bean的類型注入
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
// 判斷是否需要依賴檢查
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
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) {
// 檢查依賴
checkDependencies(beanName, mbd, filteredPds, pvs);
}
}
// 組裝屬性
applyPropertyValues(beanName, mbd, bw, pvs);
}
通過查看代碼，可知上面不止做了組裝bean這一件事，主要做了下面幾件事情:
- 獲取spring配置項中配置的
property屬性依賴 - 執(zhí)行實現(xiàn)了
InstantiationAwareBeanPostProcessors接口的方法，該接口可以在屬性被注入前做一些修改，并且可以直接返回，不執(zhí)行下面的屬性注入邏輯 - 判斷是否有配置自動注入，有的話會按配置執(zhí)行按名稱（
autowireByName方法）或類型（autowireByType方法）注入 - 判斷是否執(zhí)行依賴檢查（按配置的依賴檢查等級check）
- 最后執(zhí)行bean屬性的最終裝配 （
applyPropertyValues(beanName, mbd, bw, pvs)）
我們可以簡單看一下 autowireByName的實現(xiàn)
autowireByName
protected void autowireByName(
String beanName, AbstractBeanDefinition mbd, BeanWrapper bw, MutablePropertyValues pvs) {
// 返回需要自動依賴注入的屬性名稱
String[] propertyNames = unsatisfiedNonSimpleProperties(mbd, bw);
for (String propertyName : propertyNames) {
if (containsBean(propertyName)) {
Object bean = getBean(propertyName);
// 將獲取的依賴bean放回 待裝配
pvs.add(propertyName, bean);
registerDependentBean(propertyName, beanName);
if (logger.isDebugEnabled()) {
logger.debug("Added autowiring by name from bean name '" + beanName +
"' via property '" + propertyName + "' to bean named '" + propertyName + "'");
}
}
else {
if (logger.isTraceEnabled()) {
logger.trace("Not autowiring property '" + propertyName + "' of bean '" + beanName +
"' by name: no matching bean found");
}
}
}
}
可知如果是按name注入的話，首先會先獲取需要自動依賴注入的bean名稱，然后是通過getBean(beanName)獲取依賴項的。同理autowireByType
applyPropertyValues
在執(zhí)行applyPropertyValues方法之前，我們已經(jīng)準備好了所有的依賴項了，接下來的事情就是把這些依賴項裝配到bean對應(yīng)的屬性中
protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
// 待裝配的屬性為空 直接返回
if (pvs == null || pvs.isEmpty()) {
return;
}
MutablePropertyValues mpvs = null;
List<PropertyValue> original;
if (System.getSecurityManager() != null) {
if (bw instanceof BeanWrapperImpl) {
((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
}
}
//
if (pvs instanceof MutablePropertyValues) {
mpvs = (MutablePropertyValues) pvs;
if (mpvs.isConverted()) {
// Shortcut: use the pre-converted values as-is.
try {
bw.setPropertyValues(mpvs);
return;
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
original = mpvs.getPropertyValueList();
}
else {
original = Arrays.asList(pvs.getPropertyValues());
}
TypeConverter converter = getCustomTypeConverter();
if (converter == null) {
converter = bw;
}
// 用于加載beanDefinition所對應(yīng)的值
BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
// 創(chuàng)建一個PropertyValue的深拷貝
List<PropertyValue> deepCopy = new ArrayList<PropertyValue>(original.size());
boolean resolveNecessary = false;
for (PropertyValue pv : original) {
if (pv.isConverted()) {
deepCopy.add(pv);
}
else {
String propertyName = pv.getName();
Object originalValue = pv.getValue();
// 加載對應(yīng)屬性值 value
Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
Object convertedValue = resolvedValue;
boolean convertible = bw.isWritableProperty(propertyName) &&
!PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
if (convertible) {
convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
}
// Possibly store converted value in merged bean definition,
// in order to avoid re-conversion for every created bean instance.
if (resolvedValue == originalValue) {
if (convertible) {
pv.setConvertedValue(convertedValue);
}
deepCopy.add(pv);
}
else if (convertible && originalValue instanceof TypedStringValue &&
!((TypedStringValue) originalValue).isDynamic() &&
!(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
pv.setConvertedValue(convertedValue);
deepCopy.add(pv);
}
else {
resolveNecessary = true;
deepCopy.add(new PropertyValue(pv, convertedValue));
}
}
}
if (mpvs != null && !resolveNecessary) {
mpvs.setConverted();
}
// Set our (possibly massaged) deep copy.
try {
// 設(shè)置屬性信息
bw.setPropertyValues(new MutablePropertyValues(deepCopy));
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
這段代碼做的主要事情就是通過配置的屬性去加載屬性對應(yīng)的值，真正為bean設(shè)置屬性的邏輯在bw.setPropertyValues(new MutablePropertyValues(deepCopy))中，這里其實就是通過反射調(diào)用set方法進行屬性的設(shè)置的。
代碼執(zhí)行到這里，bean的創(chuàng)建已經(jīng)基本完整了,populateBean方法的工作已經(jīng)完成了，下面要做的就是一些初始化的工作
initializeBean(beanName, exposedObject, mbd)
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
// 安全管理器 判斷執(zhí)行權(quán)限
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
invokeAwareMethods(beanName, bean);
return null;
}
}, getAccessControlContext());
}
else {
// 執(zhí)行實現(xiàn)了一系列Aware的接口方法
invokeAwareMethods(beanName, bean);
}
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
// 執(zhí)行BeanPostProcessor接口postProcessBeforeInitialization方法
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
// 先執(zhí)行InitializingBean接口afterPropertiesSet方法
// 再執(zhí)行自定義配置的初始化方法(init-method)
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
if (mbd == null || !mbd.isSynthetic()) {
// 執(zhí)行BeanPostProcessor接口postProcessAfterInitialization方法
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
上述代碼做的都是bean初始化的事情
-
invokeAwareMethods方法，如果有bean又實現(xiàn)Aware相關(guān)的接口，則調(diào)用這些接口的方法給bean注入一些信息(beanName，BeanClassLoader，BeanFactory) -
applyBeanPostProcessorsBeforeInitialization執(zhí)行BeanPostProcessor接口postProcessBeforeInitialization方法，BeanPostProcessor接口在上一篇解析中有講到過，是在refresh方法的registerBeanPostProcessors(beanFactory)中注冊的，是spring提供的非常重要的一個自定義擴展點 -
invokeInitMethods方法，這里是判斷是否有實現(xiàn)InitializingBean接口，有則執(zhí)行afterPropertiesSet初始化方法，并且如果有配置自定義的init-method方法則也一并執(zhí)行 -
applyBeanPostProcessorsBeforeInitialization執(zhí)行BeanPostProcessor接口postProcessAfterInitialization方法
尾言
隨著解析進行到這里，我們已經(jīng)把
bean的整個生命周期都走了個大概。相信大家對spring ioc的具體實現(xiàn)已經(jīng)有了個基本的了解了
Spring 系列
