一、前面说了bean的容器初始化，后面当然是说bean的加载。这里还是不讲解ApplicationContext的bean的加载过程，还是通过最基础的XmlBeanFactory来进行讲解，主要是熟悉通过BeanFactory是怎么实现class的实例化的。
二、声明一下：XmlBeanFactory和ApplicationContext的不同在与，ApplicationContext在容器初始化的时候，就做了很多准备操作。而XmlBeanFactory是在获取bean的时候才会调用初始化的东西。这一点是XmlBeanFactory做的不好的地方。比如：BeanPostProcessor、InitializingBean和标签init-method等，这些都是在bean加载的时候完成而不是在初始化的时候。
三、bean的加载源码解读
1）bean的获取方式
package com.pinnet.bean;
import com.pinnet.customLabel.User;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
public class Test {
public static void main(String[] args) {
//读取资源
Resource resource = new ClassPathResource("spring-bean.xml");
//初始化容器
XmlBeanFactory xmlBeanFactory = new XmlBeanFactory(resource);
//获取对应的bean
xmlBeanFactory.getBean("user", User.class);
}
}
2）getBean
public <T> T getBean(String name, Class<T> requiredType) throws BeansException {
return this.doGetBean(name, requiredType, (Object[])null, false);
}
protected <T> T doGetBean(String name, Class<T> requiredType, final Object[] args, boolean typeCheckOnly) throws BeansException {
//检查是否存在别名，采用存在别名的方式
final String beanName = this.transformedBeanName(name);
//通过单例的map来获取实例，当然这个第一次是没有的，是在加载过后放入到单例的map里面
Object sharedInstance = this.getSingleton(beanName);
Object bean;
if (sharedInstance != null && args == null) {
if (this.logger.isDebugEnabled()) {
if (this.isSingletonCurrentlyInCreation(beanName)) {
this.logger.debug("Returning eagerly cached instance of singleton bean ‘" + beanName + "‘ that is not fully initialized yet - a consequence of a circular reference");
} else {
this.logger.debug("Returning cached instance of singleton bean ‘" + beanName + "‘");
}
}
//如果存在bean的话，看是否是FactoryBean,如果是则通过factoryBean的方式加载
bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, (RootBeanDefinition)null);
} else {
if (this.isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
//如果存在父类bean的话，现价在父类
BeanFactory parentBeanFactory = this.getParentBeanFactory();
if (parentBeanFactory != null && !this.containsBeanDefinition(beanName)) {
String nameToLookup = this.originalBeanName(name);
if (args != null) {
return parentBeanFactory.getBean(nameToLookup, args);
}
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
if (!typeCheckOnly) {
this.markBeanAsCreated(beanName);
}
//获取在容器里面初始化的BeanDefinition
final RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName);
this.checkMergedBeanDefinition(mbd, beanName, args);
String[] dependsOn = mbd.getDependsOn();
String scopeName;
if (dependsOn != null) {
String[] var14 = dependsOn;
int var13 = dependsOn.length;
for(int var12 = 0; var12 < var13; ++var12) {
scopeName = var14[var12];
this.getBean(scopeName);
this.registerDependentBean(scopeName, beanName);
}
}
//所有配置默认是为单例的
if (mbd.isSingleton()) {
sharedInstance = this.getSingleton(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
try {
//这里是整个bean加载的核心
return AbstractBeanFactory.this.createBean(beanName, mbd, args);
} catch (BeansException var2) {
AbstractBeanFactory.this.destroySingleton(beanName);
throw var2;
}
}
});
//如果存在bean的话，看是否是FactoryBean,如果是则通过factoryBean的方式加载
bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
} else if (mbd.isPrototype()) {
scopeName = null;
Object prototypeInstance;
try {
this.beforePrototypeCreation(beanName);
prototypeInstance = this.createBean(beanName, mbd, args);
} finally {
this.afterPrototypeCreation(beanName);
}
//如果存在bean的话，看是否是FactoryBean,如果是则通过factoryBean的方式加载
bean = this.getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
} else {
scopeName = mbd.getScope();
Scope scope = (Scope)this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope ‘" + scopeName + "‘");
}
try {
Object scopedInstance = scope.get(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
AbstractBeanFactory.this.beforePrototypeCreation(beanName);
Object var2;
try {
var2 = AbstractBeanFactory.this.createBean(beanName, mbd, args);
} finally {
AbstractBeanFactory.this.afterPrototypeCreation(beanName);
}
return var2;
}
});
bean = this.getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
} catch (IllegalStateException var19) {
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", var19);
}
}
}
if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {
try {
return this.getTypeConverter().convertIfNecessary(bean, requiredType);
} catch (TypeMismatchException var20) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Failed to convert bean ‘" + name + "‘ to required type [" + ClassUtils.getQualifiedName(requiredType) + "]", var20);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
} else {
return bean;
}
}
3）getSingleton、getMergedLocalBeanDefinition、createBean
a、getSingleton
public Object getSingleton(String beanName) {
return this.getSingleton(beanName, true);
}
protected Object getSingleton(String beanName, boolean allowEarlyReference) {
//singletonObjects是一个map，主要是目的是存放单例bean
Object singletonObject = this.singletonObjects.get(beanName);
if (singletonObject == null) {
Map var4 = this.singletonObjects;
synchronized(this.singletonObjects) {
//如果singletonObjects没有，则在earlySingletonObjects去找
singletonObject = this.earlySingletonObjects.get(beanName);
if (singletonObject == null && allowEarlyReference) {
ObjectFactory singletonFactory = (ObjectFactory)this.singletonFactories.get(beanName);
if (singletonFactory != null) {
singletonObject = singletonFactory.getObject();
this.earlySingletonObjects.put(beanName, singletonObject);
this.singletonFactories.remove(beanName);
}
}
}
}
return singletonObject != NULL_OBJECT ? singletonObject : null;
}
b、getMergedLocalBeanDefinition
protected RootBeanDefinition getMergedLocalBeanDefinition(String beanName) throws BeansException {
//默认在mergedBeanDefinitions（map）里面查找
RootBeanDefinition mbd = (RootBeanDefinition)this.mergedBeanDefinitions.get(beanName);
//注意这里的getBeanDefinition，这里是从beanDefinitionMap里面取查找的，整个在容器加载的时候说明了
return mbd != null ? mbd : this.getMergedBeanDefinition(beanName, this.getBeanDefinition(beanName));
}
protected RootBeanDefinition getMergedBeanDefinition(String beanName, BeanDefinition bd) throws BeanDefinitionStoreException {
return this.getMergedBeanDefinition(beanName, bd, (BeanDefinition)null);
}
protected RootBeanDefinition getMergedBeanDefinition(String beanName, BeanDefinition bd, BeanDefinition containingBd) throws BeanDefinitionStoreException {
Map var4 = this.mergedBeanDefinitions;
synchronized(this.mergedBeanDefinitions) {
RootBeanDefinition mbd = null;
if (containingBd == null) {
mbd = (RootBeanDefinition)this.mergedBeanDefinitions.get(beanName);
}
if (mbd == null) {
if (bd.getParentName() == null) {
if (bd instanceof RootBeanDefinition) {
mbd = ((RootBeanDefinition)bd).cloneBeanDefinition();
} else {
//将其他类型BeanDefinition包装成RootBeanDefinition
mbd = new RootBeanDefinition(bd);
}
} else {
//父类bean不为空的操作
BeanDefinition pbd;
try {
String parentBeanName = this.transformedBeanName(bd.getParentName());
if (!beanName.equals(parentBeanName)) {
pbd = this.getMergedBeanDefinition(parentBeanName);
} else {
if (!(this.getParentBeanFactory() instanceof ConfigurableBeanFactory)) {
throw new NoSuchBeanDefinitionException(bd.getParentName(), "Parent name ‘" + bd.getParentName() + "‘ is equal to bean name ‘" + beanName + "‘: cannot be resolved without an AbstractBeanFactory parent");
}
pbd = ((ConfigurableBeanFactory)this.getParentBeanFactory()).getMergedBeanDefinition(parentBeanName);
}
} catch (NoSuchBeanDefinitionException var8) {
throw new BeanDefinitionStoreException(bd.getResourceDescription(), beanName, "Could not resolve parent bean definition ‘" + bd.getParentName() + "‘", var8);
}
mbd = new RootBeanDefinition(pbd);
mbd.overrideFrom(bd);
}
//这里默认设置成单例的
if (!StringUtils.hasLength(mbd.getScope())) {
mbd.setScope("singleton");
}
if (containingBd != null && !containingBd.isSingleton() && mbd.isSingleton()) {
mbd.setScope(containingBd.getScope());
}
if (containingBd == null && this.isCacheBeanMetadata() && this.isBeanEligibleForMetadataCaching(beanName)) {
this.mergedBeanDefinitions.put(beanName, mbd);
}
}
return mbd;
}
}
public BeanDefinition getBeanDefinition(String beanName) throws NoSuchBeanDefinitionException {
//不多解释，这里在容器初始化的时候进行操作
BeanDefinition bd = (BeanDefinition)this.beanDefinitionMap.get(beanName);
if (bd == null) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("No bean named ‘" + beanName + "‘ found in " + this);
}
throw new NoSuchBeanDefinitionException(beanName);
} else {
return bd;
}
}
c、getSingleton（这里实在调用createBean的地方）
public Object getSingleton(String beanName, ObjectFactory singletonFactory) {
Assert.notNull(beanName, "‘beanName‘ must not be null");
Map var3 = this.singletonObjects;
synchronized(this.singletonObjects) {
Object singletonObject = this.singletonObjects.get(beanName);
if (singletonObject == null) {
if (this.singletonsCurrentlyInDestruction) {
throw new BeanCreationNotAllowedException(beanName, "Singleton bean creation not allowed while the singletons of this factory are in destruction (Do not request a bean from a BeanFactory in a destroy method implementation!)");
}
if (this.logger.isDebugEnabled()) {
this.logger.debug("Creating shared instance of singleton bean ‘" + beanName + "‘");
}
//创建bean之前做的操作
this.beforeSingletonCreation(beanName);
boolean recordSuppressedExceptions = this.suppressedExceptions == null;
if (recordSuppressedExceptions) {
this.suppressedExceptions = new LinkedHashSet();
}
try {
//这里调用createBean
singletonObject = singletonFactory.getObject();
} catch (BeanCreationException var13) {
BeanCreationException ex = var13;
if (recordSuppressedExceptions) {
Iterator var8 = this.suppressedExceptions.iterator();
while(var8.hasNext()) {
Exception suppressedException = (Exception)var8.next();
ex.addRelatedCause(suppressedException);
}
}
throw ex;
} finally {
if (recordSuppressedExceptions) {
this.suppressedExceptions = null;
}
this.afterSingletonCreation(beanName);
}
//添加到单例的map里面（这里不细讲解）
this.addSingleton(beanName, singletonObject);
}
return singletonObject != NULL_OBJECT ? singletonObject : null;
}
}
d、createBean
protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Creating instance of bean ‘" + beanName + "‘");
}
//实例化beanClass，放在mbd的beanClass下面，目前当做class被实例化在beanClass下
this.resolveBeanClass(mbd, beanName, new Class[0]);
try {
//准备重写的方法，不多介绍
mbd.prepareMethodOverrides();
} catch (BeanDefinitionValidationException var5) {
throw new BeanDefinitionStoreException(mbd.getResourceDescription(), beanName, "Validation of method overrides failed", var5);
}
Object beanInstance;
try {
//处理InstantiationAwareBeanPostProcessor下的调用，该结构继承BeanPostProcessor
beanInstance = this.resolveBeforeInstantiation(beanName, mbd);
if (beanInstance != null) {
return beanInstance;
}
} catch (Throwable var6) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "BeanPostProcessor before instantiation of bean failed", var6);
}
//这里主要是做一些初始化的操作等
beanInstance = this.doCreateBean(beanName, mbd, args);
if (this.logger.isDebugEnabled()) {
this.logger.debug("Finished creating instance of bean ‘" + beanName + "‘");
}
return beanInstance;
}
d.1 resolveBeanClass
protected Class resolveBeanClass(final RootBeanDefinition mbd, String beanName, final Class... typesToMatch) throws CannotLoadBeanClassException {
try {
if (mbd.hasBeanClass()) {
return mbd.getBeanClass();
} else {
return System.getSecurityManager() != null ? (Class) AccessController.doPrivileged(new PrivilegedExceptionAction<Class>() {
public Class run() throws Exception {
return AbstractBeanFactory.this.doResolveBeanClass(mbd, typesToMatch);
}
//不存在beanClass的时候调用
}, this.getAccessControlContext()) : this.doResolveBeanClass(mbd, typesToMatch);
}
} catch (PrivilegedActionException var6) {
ClassNotFoundException ex = (ClassNotFoundException)var6.getException();
throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), ex);
} catch (ClassNotFoundException var7) {
throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), var7);
} catch (LinkageError var8) {
throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), var8);
}
}
private Class doResolveBeanClass(RootBeanDefinition mbd, Class... typesToMatch) throws ClassNotFoundException {
if (!ObjectUtils.isEmpty(typesToMatch)) {
ClassLoader tempClassLoader = this.getTempClassLoader();
if (tempClassLoader != null) {
if (tempClassLoader instanceof DecoratingClassLoader) {
DecoratingClassLoader dcl = (DecoratingClassLoader)tempClassLoader;
Class[] var8 = typesToMatch;
int var7 = typesToMatch.length;
for(int var6 = 0; var6 < var7; ++var6) {
Class<?> typeToMatch = var8[var6];
dcl.excludeClass(typeToMatch.getName());
}
}
String className = mbd.getBeanClassName();
return className != null ? ClassUtils.forName(className, tempClassLoader) : null;
}
}
//这里应为typesToMatch不为空，所以走这里
return mbd.resolveBeanClass(this.getBeanClassLoader());
}
public Class resolveBeanClass(ClassLoader classLoader) throws ClassNotFoundException {
String className = this.getBeanClassName();
if (className == null) {
return null;
} else {
//通过反射创建实例
Class resolvedClass = ClassUtils.forName(className, classLoader);
this.beanClass = resolvedClass;
return resolvedClass;
}
}
d.2 resolveBeforeInstantiation（不多解释）
protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
Object bean = null;
if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
if (mbd.hasBeanClass() && !mbd.isSynthetic() && this.hasInstantiationAwareBeanPostProcessors()) {
bean = this.applyBeanPostProcessorsBeforeInstantiation(mbd.getBeanClass(), beanName);
if (bean != null) {
bean = this.applyBeanPostProcessorsAfterInitialization(bean, beanName);
}
}
mbd.beforeInstantiationResolved = bean != null;
}
return bean;
}
d.3 doCreateBean
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, Object[] args) {
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = (BeanWrapper)this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
instanceWrapper = this.createBeanInstance(beanName, mbd, args);
}
final Object bean = instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null;
Class beanType = instanceWrapper != null ? instanceWrapper.getWrappedClass() : null;
Object var7 = mbd.postProcessingLock;
synchronized(mbd.postProcessingLock) {
if (!mbd.postProcessed) {
//这里的处理方式和c.2的处理方式类似
this.applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
mbd.postProcessed = true;
}
}
boolean earlySingletonExposure = mbd.isSingleton() && this.allowCircularReferences && this.isSingletonCurrentlyInCreation(beanName);
if (earlySingletonExposure) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Eagerly caching bean ‘" + beanName + "‘ to allow for resolving potential circular references");
}
this.addSingletonFactory(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
return AbstractAutowireCapableBeanFactory.this.getEarlyBeanReference(beanName, mbd, bean);
}
});
}
Object exposedObject = bean;
try {
this.populateBean(beanName, mbd, instanceWrapper);
if (exposedObject != null) {
//这里就是初始化的方法了
exposedObject = this.initializeBean(beanName, exposedObject, mbd);
}
} catch (Throwable var17) {
if (var17 instanceof BeanCreationException && beanName.equals(((BeanCreationException)var17).getBeanName())) {
throw (BeanCreationException)var17;
}
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", var17);
}
if (earlySingletonExposure) {
Object earlySingletonReference = this.getSingleton(beanName, false);
if (earlySingletonReference != null) {
if (exposedObject == bean) {
exposedObject = earlySingletonReference;
} else if (!this.allowRawInjectionDespiteWrapping && this.hasDependentBean(beanName)) {
String[] dependentBeans = this.getDependentBeans(beanName);
Set<String> actualDependentBeans = new LinkedHashSet(dependentBeans.length);
String[] var15 = dependentBeans;
int var14 = dependentBeans.length;
for(int var13 = 0; var13 < var14; ++var13) {
String dependentBean = var15[var13];
if (!this.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.");
}
}
}
}
try {
this.registerDisposableBeanIfNecessary(beanName, bean, mbd);
return exposedObject;
} catch (BeanDefinitionValidationException var16) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", var16);
}
}
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
AbstractAutowireCapableBeanFactory.this.invokeAwareMethods(beanName, bean);
return null;
}
}, this.getAccessControlContext());
} else {
this.invokeAwareMethods(beanName, bean);
}
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
//执行BeanPostProcessors的postProcessBeforeInitialization方法
wrappedBean = this.applyBeanPostProcessorsBeforeInitialization(bean, beanName);
}
try {
//执行实现InitializingBean，和init-method标签的内容
this.invokeInitMethods(beanName, wrappedBean, mbd);
} catch (Throwable var6) {
throw new BeanCreationException(mbd != null ? mbd.getResourceDescription() : null, beanName, "Invocation of init method failed", var6);
}
if (mbd == null || !mbd.isSynthetic()) {
//执行BeanPostProcessors的postProcessAfterInitialization方法
wrappedBean = this.applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) throws BeansException {
Object result = existingBean;
Iterator var5 = this.getBeanPostProcessors().iterator();
while(var5.hasNext()) {
BeanPostProcessor beanProcessor = (BeanPostProcessor)var5.next();
result = beanProcessor.postProcessBeforeInitialization(result, beanName);
if (result == null) {
return result;
}
}
return result;
}
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
Object result = existingBean;
Iterator var5 = this.getBeanPostProcessors().iterator();
while(var5.hasNext()) {
BeanPostProcessor beanProcessor = (BeanPostProcessor)var5.next();
result = beanProcessor.postProcessAfterInitialization(result, beanName);
if (result == null) {
return result;
}
}
return result;
}
protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd) throws Throwable {
boolean isInitializingBean = bean instanceof InitializingBean;
if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Invoking afterPropertiesSet() on bean with name ‘" + beanName + "‘");
}
if (System.getSecurityManager() != null) {
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
((InitializingBean)bean).afterPropertiesSet();
return null;
}
}, this.getAccessControlContext());
} catch (PrivilegedActionException var6) {
throw var6.getException();
}
} else {
//调用InitializingBean接口的afterPropertiesSet方法，初始化
((InitializingBean)bean).afterPropertiesSet();
}
}
if (mbd != null) {
String initMethodName = mbd.getInitMethodName();
if (initMethodName != null && (!isInitializingBean || !"afterPropertiesSet".equals(initMethodName)) && !mbd.isExternallyManagedInitMethod(initMethodName)) {
//执行init-method的方法，如果afterPropertiesSet执行出现异常，是不会执行init-method的方法的
this.invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
protected void invokeCustomInitMethod(String beanName, final Object bean, RootBeanDefinition mbd) throws Throwable {
String initMethodName = mbd.getInitMethodName();
final Method initMethod = mbd.isNonPublicAccessAllowed() ? BeanUtils.findMethod(bean.getClass(), initMethodName, new Class[0]) : ClassUtils.getMethodIfAvailable(bean.getClass(), initMethodName, new Class[0]);
if (initMethod == null) {
if (mbd.isEnforceInitMethod()) {
throw new BeanDefinitionValidationException("Couldn‘t find an init method named ‘" + initMethodName + "‘ on bean with name ‘" + beanName + "‘");
} else {
if (this.logger.isDebugEnabled()) {
this.logger.debug("No default init method named ‘" + initMethodName + "‘ found on bean with name ‘" + beanName + "‘");
}
}
} else {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Invoking init method ‘" + initMethodName + "‘ on bean with name ‘" + beanName + "‘");
}
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
ReflectionUtils.makeAccessible(initMethod);
return null;
}
});
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
initMethod.invoke(bean);
return null;
}
}, this.getAccessControlContext());
} catch (PrivilegedActionException var9) {
InvocationTargetException ex = (InvocationTargetException)var9.getException();
throw ex.getTargetException();
}
} else {
try {
ReflectionUtils.makeAccessible(initMethod);
//执行方法
initMethod.invoke(bean);
} catch (InvocationTargetException var8) {
throw var8.getTargetException();
}
}
}
}
d.4 创建bean的过程结束了，这里主要的目的是初始化。
四、bean的加载基本上就是这样了，不过还是梳理一下比较好
1）通过getBean的方式进行，进行bean的获取
2）bean的获取现从singletonObjects中获取，如果没有在进行createBean
3）bean的获取是从beanDefinitionMap里面开始的，获取到对应的BeanDefinition，然后在进行处理
4）createBean的过程中是实例化了bean并放入BeanDefinition的，然后进行了各种初始化
5）在调用createBean的结束的时候在将bean放入了singletonObjects单例里面，这个实在源码解析c中描述的
6）将获得bean进行返回，如果存在class类型，则适配返回，没有就object
五、bean的加载过程基本上流程就这样，当然源码的解析过程，是比较痛苦的，但是在实现他的每一个实现都有他的意义。我这里只是更明显的阐述，实际的调用过程。当然这只是开始，后续的东西都是以此基础来进行拓展的。特别是在自定义标签环节。基本上拓展的新功能，都是在自定义标签下面实现的。
六、bean的基本过程就是这样子了，然后就是后续的拓展功能，bean的增强化，还是自定义标签的使用上面，后续都会一一呈现，目的是更好的理解spring的拓展性和易用性
原文地址：https://www.cnblogs.com/ll409546297/p/9482669.html
时间： 2024-10-09 00:42:27