1.注冊(cè)
//存儲(chǔ)注冊(cè)的俄BeanDefinition
private final Map beanDefinitionMap = new ConcurrentHashMap();
//向IoC容器注冊(cè)解析的BeanDefiniton
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
????Assert.hasText(beanName, "Bean name must not be empty");
????Assert.notNull(beanDefinition, "BeanDefinition must not be null");
? ? //校驗(yàn)解析的BeanDefiniton，判斷
????if (beanDefinition instanceof AbstractBeanDefinition) {
????try {
????????((AbstractBeanDefinition) beanDefinition).validate();
????}catch (BeanDefinitionValidationException ex) {
????????throw new ? ?
????????BeanDefinitionStoreException(beanDefinition.getResourceDescription(),
????????beanName,"Validation of bean definition failed", ex);
????}
}
//注冊(cè)的過(guò)程中需要線程同步，以保證數(shù)據(jù)的一致性
synchronized (this.beanDefinitionMap) {
????Object oldBeanDefinition = this.beanDefinitionMap.get(beanName);
}
//檢查是否有同名的BeanDefinition已經(jīng)在IoC容器中注冊(cè)，如果已經(jīng)注冊(cè)，
//并且不允許覆蓋已注冊(cè)的Bean，則拋出注冊(cè)失敗異常
if (oldBeanDefinition != null) {
????if (!this.allowBeanDefinitionOverriding) {
????????throw new
? ? ? ?BeanDefinitionStoreException(beanDefinition.getResourceDescription(), ????????
? ? ? ?beanName,"Cannot register bean definition [" + beanDefinition + "] for bean '" +?
? ? ? beanName +"': There is already [" + oldBeanDefinition + "] bound.");
}else {
????//如果允許覆蓋，則同名的Bean，后注冊(cè)的覆蓋先注冊(cè)的
????????if (this.logger.isInfoEnabled()) {
????????????this.logger.info("Overriding bean definition for bean '" + beanName +"': ????
????????????replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]");
????????}????
????}
}
//IoC容器中沒(méi)有已經(jīng)注冊(cè)同名的Bean，按正常注冊(cè)流程注冊(cè)
else {
????this.beanDefinitionNames.add(beanName);
? ? this.frozenBeanDefinitionNames = null;
}
????????this.beanDefinitionMap.put(beanName, beanDefinition);
????????//重置所有已經(jīng)注冊(cè)過(guò)的BeanDefinition的緩存
????????resetBeanDefinition(beanName);
????}
}?
2.注入
protected T doGetBean(final String name, final Class requiredType,?
????????final Object[] args, boolean typeCheckOnly)throws BeansException {
????//根據(jù)指定的名稱獲取被管理Bean的名稱，剝離指定名稱中對(duì)容器的相關(guān)依賴
????//如果指定的是別名，將別名轉(zhuǎn)換為規(guī)范的Bean名稱
????final String beanName = transformedBeanName(name);
????Object bean;
????//先從緩存中取是否已經(jīng)有被創(chuàng)建過(guò)的單態(tài)類型的Bean，對(duì)于單態(tài)模式的Bean整
? ? //個(gè)IoC容器中只創(chuàng)建一次，不需要重復(fù)創(chuàng)建
????Object sharedInstance = getSingleton(beanName);
????//IoC容器創(chuàng)建單態(tài)模式Bean實(shí)例對(duì)象
????if (sharedInstance != null && args == null) {
????????if (logger.isDebugEnabled()) {
????????//如果指定名稱的Bean在容器中已有單態(tài)模式的Bean被創(chuàng)建，直接返回
????????//已經(jīng)創(chuàng)建的Bean
????????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 + "'");
????????}
}
????//獲取給定Bean的實(shí)例對(duì)象，主要是完成FactoryBean的相關(guān)處理
????//注意：BeanFactory是管理容器中Bean的工廠，而FactoryBean是
????//創(chuàng)建創(chuàng)建對(duì)象的工廠Bean，兩者之間有區(qū)別
????bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}else {
//緩存沒(méi)有正在創(chuàng)建的單態(tài)模式Bean
//緩存中已經(jīng)有已經(jīng)創(chuàng)建的原型模式Bean，但是由于循環(huán)引用的問(wèn)題導(dǎo)致實(shí)
//例化對(duì)象失敗
if (isPrototypeCurrentlyInCreation(beanName)) {
????throw new BeanCurrentlyInCreationException(beanName);
}
//對(duì)IoC容器中是否存在指定名稱的BeanDefinition進(jìn)行檢查，首先檢查是否
//能在當(dāng)前的BeanFactory中獲取的所需要的Bean，如果不能則委托當(dāng)前容器
//的父級(jí)容器去查找，如果還是找不到則沿著容器的繼承體系向父級(jí)容器查找
BeanFactory parentBeanFactory = getParentBeanFactory();
//當(dāng)前容器的父級(jí)容器存在，且當(dāng)前容器中不存在指定名稱的Bean
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
????//解析指定Bean名稱的原始名稱
????String nameToLookup = originalBeanName(name);
????if (args != null) {
????//委派父級(jí)容器根據(jù)指定名稱和顯式的參數(shù)查找
????return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else {
????//委派父級(jí)容器根據(jù)指定名稱和類型查找
????return parentBeanFactory.getBean(nameToLookup, requiredType);
}
}
//創(chuàng)建的Bean是否需要進(jìn)行類型驗(yàn)證，一般不需要
if (!typeCheckOnly) {
????//向容器標(biāo)記指定的Bean已經(jīng)被創(chuàng)建
????markBeanAsCreated(beanName);????
}
//根據(jù)指定Bean名稱獲取其父級(jí)的Bean定義，主要解決Bean繼承時(shí)子類
//合并父類公共屬性問(wèn)題
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
//獲取當(dāng)前Bean所有依賴Bean的名稱
String[] dependsOn = mbd.getDependsOn();
//如果當(dāng)前Bean有依賴Bean
if (dependsOn != null) {
for (String dependsOnBean : dependsOn) {
//遞歸調(diào)用getBean方法，獲取當(dāng)前Bean的依賴Bean
????getBean(dependsOnBean);
????//把被依賴Bean注冊(cè)給當(dāng)前依賴的Bean
????registerDependentBean(dependsOnBean, beanName);
????}
}
//創(chuàng)建單態(tài)模式Bean的實(shí)例對(duì)象
if (mbd.isSingleton()) {
//這里使用了一個(gè)匿名內(nèi)部類，創(chuàng)建Bean實(shí)例對(duì)象，并且注冊(cè)給所依賴的對(duì)象
????sharedInstance = getSingleton(beanName, new ObjectFactory() {
????public Object getObject() throws BeansException {
????try {
????????//創(chuàng)建一個(gè)指定Bean實(shí)例對(duì)象，如果有父級(jí)繼承，則合并子//類和父類的定義
????????return createBean(beanName, mbd, args);
????}catch (BeansException ex) {
? ? ?????//顯式地從容器單態(tài)模式Bean緩存中清除實(shí)例對(duì)象
????????destroySingleton(beanName);
????????throw ex;
????}
}
});
????//獲取給定Bean的實(shí)例對(duì)象
????bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
????//IoC容器創(chuàng)建原型模式Bean實(shí)例對(duì)象
else if (mbd.isPrototype()) {
????//原型模式(Prototype)是每次都會(huì)創(chuàng)建一個(gè)新的對(duì)象
????Object prototypeInstance = null;
try {
????//回調(diào)beforePrototypeCreation方法，默認(rèn)的功能是注冊(cè)當(dāng)前創(chuàng)//建的原型對(duì)象
????beforePrototypeCreation(beanName);
????//創(chuàng)建指定Bean對(duì)象實(shí)例
????prototypeInstance = createBean(beanName, mbd, args);
}finally {
????????//回調(diào)afterPrototypeCreation方法，默認(rèn)的功能告訴IoC容器指//定Bean的原型對(duì)象不再創(chuàng)建了
????????afterPrototypeCreation(beanName);
}
????????//獲取給定Bean的實(shí)例對(duì)象
????????bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
????//要?jiǎng)?chuàng)建的Bean既不是單態(tài)模式，也不是原型模式，則根據(jù)Bean定義資源中
????//配置的生命周期范圍，選擇實(shí)例化Bean的合適方法，這種在Web應(yīng)用程序中
????//比較常用，如：request、session、application等生命周期
else {
????String scopeName = mbd.getScope();
????final Scope scope = this.scopes.get(scopeName);
????//Bean定義資源中沒(méi)有配置生命周期范圍，則Bean定義不合法
????if (scope == null) {
????????throw new IllegalStateException("No Scope registered for scope '" + scopeName + "'");
????}
try {
//這里又使用了一個(gè)匿名內(nèi)部類，獲取一個(gè)指定生命周期范圍的實(shí)例
Object scopedInstance = scope.get(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
}
});
//獲取給定Bean的實(shí)例對(duì)象
????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);
}
}
}
//對(duì)創(chuàng)建的Bean實(shí)例對(duì)象進(jìn)行類型檢查
if (requiredType != null && bean != null &&?
!requiredType.isAssignableFrom(bean.getClass())) {
????throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
????return (T) bean;
}
