spring 笔记5 bean的生命周期,BeanPostProcessor
BeanPostProcessor接口
public interface BeanPostProcessor {
Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;//初始化
Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;
}
public interface DestructionAwareBeanPostProcessor extends BeanPostProcessor {
void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException;//毁掉
}
public interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor {
Object postProcessBeforeInstantiation(Class beanClass, String beanName) throws BeansException;//实例化
boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException;
PropertyValues postProcessPropertyValues(
PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName)
throws BeansException;
}
public interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor {
Class predictBeanType(Class beanClass, String beanName) throws BeansException;
Constructor[] determineCandidateConstructors(Class beanClass, String beanName) throws BeansException;
Object getEarlyBeanReference(Object bean, String beanName) throws BeansException;
}
public interface MergedBeanDefinitionPostProcessor extends BeanPostProcessor {
void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class beanType, String beanName);
}//方法1
@Override
protected Object createBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
throws BeanCreationException {
if (logger.isDebugEnabled()) {
logger.debug("Creating instance of bean '" + beanName + "'");
}
// Make sure bean class is actually resolved at this point.
resolveBeanClass(mbd, beanName);
// Prepare method overrides.
try {
mbd.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbd.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
try {
/*/1 Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
//给BeanPostProcessors一个机会返回一个代理类替代目标对象？
Object bean = resolveBeforeInstantiation(beanName, mbd);
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
Object beanInstance = doCreateBean(beanName, mbd, args);
if (logger.isDebugEnabled()) {
logger.debug("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}
注释
/*/1
protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
Object bean = null;
if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
// Make sure bean class is actually resolved at this point.
if (mbd.hasBeanClass() && !mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
bean = applyBeanPostProcessorsBeforeInstantiation(mbd.getBeanClass(), beanName);
//取工厂中的InstantiationAwareBeanPostProcessor执行postProcessBeforeInstantiation方法
//不少实现类此方法都是返回null ?
if (bean != null) {
bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
//取工厂中所有的BeanPostProcessor 执行postProcessAfterInitialization方法
}
}
mbd.beforeInstantiationResolved = (bean != null);
}
return bean;
}
//方法2
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
// Instantiate the bean.
....
instanceWrapper = createBeanInstance(beanName, mbd, args);
//createBeanInstance{
// Constructor[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
// //取工厂中的SmartInstantiationAwareBeanPostProcessor 执行determineCandidateConstructors得到Constructor[]
//
//
//
//
// autowireConstructor();
// instantiateBean(){;//无参的构造方法
// beanInstance = getInstantiationStrategy().instantiate(mbd, beanName, parent);
// //getInstantiationStrategy() = CglibSubclassingInstantiationStrategy()
// //constructorToUse = clazz.getDeclaredConstructor((Class[]) null);
// //beanDefinition.resolvedConstructorOrFactoryMethod = constructorToUse;
// //return BeanUtils.instantiateClass(constructorToUse);(实现使用方法ctor.newInstance(args);)
// }
//}
....
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
//
//取工厂中所有的MergedBeanDefinitionPostProcessor执行postProcessMergedBeanDefinition方法
//
//
//
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() {
public Object getObject() throws BeansException {
return getEarlyBeanReference(beanName, mbd, bean);
//
//取工厂中所有的SmartInstantiationAwareBeanPostProcessor执行getEarlyBeanReference返回
//
//
//
}
});
}
// Initialize the bean instance.实例化
Object exposedObject = bean;
try {
populateBean(beanName, mbd, instanceWrapper);//把从definnation装好property的实例装进wrapper
//实例化前
//取工厂中任何一个InstantiationAwareBeanPostProcessor执行postProcessAfterInstantiation（实例化后）方法，如果返回false不设置属性了
//
//applyPropertyValues(beanName, mbd, bw, pvs)
//应用给定的属性值，解决任何运行时引用
//到这个bean工厂的其他bean。必须使用深拷贝，所以我们
//不要永久修改此属性。
// PropertyAccessor.setPropertyValues
// Method.invoke(obj,args)设置属性
//
//
if (exposedObject != null) {
exposedObject = initializeBean(beanName, exposedObject, mbd);
//
//invokeAwareMethods() 执行bean实现BeanNameAware BeanClassLoaderAware BeanFactoryAware的方法
//applyBeanPostProcessorsBeforeInitialization() 执行工厂中所有的BeanPostProcessor的postProcessBeforeInitialization方法
//invokeInitMethods() 执行afterPropertiesSet方法
// invokeCustomInitMethod()执行配置的init-method方法
//applyBeanPostProcessorsAfterInitialization() 执行工厂中所有BeanPostProcessor的postProcessAfterInitialization方法
//
//
}
}
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 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 " +
"'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
//把给定的bean添加到工厂的disposable beans列表中，注册它实现的DisposableBean方法或者destroy方法，
//当工厂关闭时候调用，只使用单例bean
//
//
//
//
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
//方法3
AbstractBeanFactory#destroyBean(String beanName, Object beanInstance, RootBeanDefinition mbd){
new DisposableBeanAdapter(beanInstance, beanName, mbd, getBeanPostProcessors(), getAccessControlContext()).destroy();
//DestructionAwareBeanPostProcessor 执行postProcessBeforeDestruction方法
//((DisposableBean) bean).destroy(); 执行实现DisposableBean的destroy方法
//invokeCustomDestroyMethod(this.destroyMethod);执行配置的destroy方法
}最后引用网上两张图片：
