Spring Bean 循环依赖

Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException:
 Error creating bean with name 'xxxManageFacadeImpl': Bean with name 'xxxManageFacadeImpl'  has been injected into other beans [xxxProductMaintenceFacadeImpl]
 in its raw version as part of a circular reference, but has eventually been wrap means thff, for expped. 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 'getBeanNamesallowEageOfType' with the 'allowEagerInit' flag turned off, for example

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)
        throws BeanCreationException {
    if (mbd.isSingleton()) {
        instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
    }
    // Bean初始化第一步：默认调用无参构造实例化Bean
    // 如果是只有带参数的构造方法，构造方法里的参数依赖注入，就是发生在这一步
    if (instanceWrapper == null) {
        instanceWrapper = createBeanInstance(beanName, mbd, args);
    }
    // Initialize the bean instance.
    Object exposedObject = bean;
    try {
        // bean创建第二步：填充属性（DI依赖注入发生在此步骤）
        populateBean(beanName, mbd, instanceWrapper);
        // bean创建第三步：调用初始化方法，完成bean的初始化操作（AOP的第三个入口）
        // AOP是通过自动代理创建器AbstractAutoProxyCreator的postProcessAfterInitialization()
//方法的执行进行代理对象的创建的,AbstractAutoProxyCreator是BeanPostProcessor接口的实现
        exposedObject = initializeBean(beanName, exposedObject, mbd);
    }
    catch (Throwable ex) {
        // ...
    }
    // ...

// AbstractBeanFactory.java
    protected <T> T doGetBean(final String name, @Nullable final Class<T> requiredType,
                              @Nullable final Object[] args, boolean typeCheckOnly) throws BeansException {
        final String beanName = transformedBeanName(name);
        // 1.尝试从缓存中获取bean，AService还没创建三级缓存都没命中
        Object sharedInstance = getSingleton(beanName);
        if (mbd.isSingleton()) {

            sharedInstance = getSingleton(beanName,    () -> {  //注意此处参数是一个lambda表达式即参数传入的是ObjectFactory类型一个匿名内部类对象
                                                        try {
                                                            return createBean(beanName, mbd, args);  // 
                                                        }
                                                        catch (BeansException ex) {}
                                                    });
            beanInstance = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
        }
    }

public Object getSingleton(String beanName, ObjectFactory singletonFactory) {
//将当前beanName放到singletonsCurrentlyInCreation 集合中，标识该bean正在创建
    beforeSingletonCreation(beanName);
    //通过回调getObject()方法触发AbstractAutowireCapableBeanFactory#createBean(String beanName, RootBeanDefinition mbd, Object[] args)的执行
    singletonObject = singletonFactory.getObject();
    afterSingletonCreation(beanName);
    addSingleton(beanName, singletonObject);
}

//真正创建Bean的地方 AbstractAutowireCapableBeanFactory#doCreateBean
    protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)  throws BeanCreationException {

        // Instantiate the bean.
        BeanWrapper instanceWrapper = null;
        if (mbd.isSingleton()) {
            instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
        }
        // bean初始化第一步：默认调用无参构造实例化Bean
        // 构造参数依赖注入，就是发生在这一步
        if (instanceWrapper == null) {
            instanceWrapper = createBeanInstance(beanName, mbd, args);
        }
        // 实例化后的Bean对象
        final Object bean = instanceWrapper.getWrappedInstance();
        // 将刚创建的bean放入三级缓存中singleFactories(key是beanName，value是ObjectFactory)
        //注意此处参数又是一个lambda表达式即参数传入的是ObjectFactory类型一个匿名内部类对象，在后续再缓存中查找Bean时会触发匿名内部类getEarlyBeanReference()方法回调
        addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
        // Initialize the bean instance.
        Object exposedObject = bean;
        try {
            // bean创建第二步：填充属性（DI依赖注入发生在此步骤）
            populateBean(beanName, mbd, instanceWrapper);
            // bean创建第三步：调用初始化方法，完成bean的初始化操作（AOP的第三个入口）
            // AOP是通过自动代理创建器AbstractAutoProxyCreator的postProcessAfterInitialization()
//方法的执行进行代理对象的创建的,AbstractAutoProxyCreator是BeanPostProcessor接口的实现
            exposedObject = initializeBean(beanName, exposedObject, mbd);
        }
        catch (Throwable ex) {
            // ...
        }

    }

//DefaultSingletonBeanRegistry.java
public Object getSingleton(String beanName) {
    return getSingleton(beanName, true);
}
protected Object getSingleton(String beanName, boolean allowEarlyReference) {
        // 从一级缓存获取，key=AService
        Object singletonObject = this.singletonObjects.get(beanName);
        if (singletonObject == null && isSingletonCurrentlyInCreation(beanName)) {
            synchronized (this.singletonObjects) {
                // 从二级缓存获取，key=AService 
                singletonObject = this.earlySingletonObjects.get(beanName);
                // 是否允许循环引用
                if (singletonObject == null && allowEarlyReference) {
                   // 前面已经将以Key为AService，value是ObjectFactory类型一个匿名内部类对象放入三级缓存了
                    ObjectFactory<?> singletonFactory = this.singletonFactories.get(beanName);
                    if (singletonFactory != null) {
                         //singletonFactory是一个匿名内部类对象，此处触发匿名内部类中getEarlyBeanReference()方法回调。
                        singletonObject = singletonFactory.getObject();
                        // 将三级缓存生产的bean放入二级缓存中
                        this.earlySingletonObjects.put(beanName, singletonObject);
                        // 删除三级缓存
                        this.singletonFactories.remove(beanName);
                    }
                }
            }
        }
        return singletonObject;
    }

// 将Aservice添加三级缓存
addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
// 添加Bservice的aService属性时从三级中找Aservice的ObjectFactory类型一个匿名内部类对象，从而触发匿名内部类getEarlyBeanReference()方法回调，进入创建AService切面代理对象逻辑
protected Object getEarlyBeanReference(String beanName, RootBeanDefinition mbd, Object bean) {
    Object exposedObject = bean;
    if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
        //判断后置处理器是否实现了SmartInstantiationAwareBeanPostProcessor接口
        //调用SmartInstantiationAwareBeanPostProcessor的getEarlyBeanReference
        for (SmartInstantiationAwareBeanPostProcessor bp : getBeanPostProcessorCache().smartInstantiationAware) {
            exposedObject = bp.getEarlyBeanReference(exposedObject, beanName);
        }
    }
    return exposedObject;
}

//真正实现了该方法的类就是AbstractAutoProxyCreator
public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
      implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware { 
    @Override
    public Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
        // 先获取beanName,主要是为FactoryBean类型添加&前缀
        Object cacheKey = getCacheKey(bean.getClass(), beanName);
        // 判断是否已经在earlyProxyReferences集合中，不在则添加进去
        if (!this.earlyProxyReferences.contains(cacheKey)) {
            this.earlyProxyReferences.add(cacheKey);
        }
        // 创建代理对象，如果必要的话
        return wrapIfNecessary(bean, beanName, cacheKey);
    }  
    /**
     * Wrap the given bean if necessary, i.e. if it is eligible for being proxied.
     * @param bean the raw bean instance
     * @param beanName the name of the bean
     * @param cacheKey the cache key for metadata access
     * @return a proxy wrapping the bean, or the raw bean instance as-is
     */
    protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
        // 前面先做一些基本的判断
        if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {
            return bean;
        }
        if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
            return bean;
        }
        // Advice/Pointcut/Advisor/AopInfrastructureBean接口的beanClass不进行代理以及对beanName为aop内的切面名也不进行代理
        // 此处可查看子类复写的shouldSkip()方法
        if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
            this.advisedBeans.put(cacheKey, Boolean.FALSE);
            return bean;
        }
        // Create proxy if we have advice.
        // 查找对代理类相关的advisor对象集合，此处就与point-cut表达式有关了
        Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
        // 对相应的advisor不为空才采取代理
        if (specificInterceptors != DO_NOT_PROXY) {
            this.advisedBeans.put(cacheKey, Boolean.TRUE);
            // 通过jdk动态代理或者cglib动态代理，产生代理对象,这里传入的是SingletonTargetSource对象喔，对原始bean对象进行了包装
            Object proxy = createProxy(
                    bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
            // 放入代理类型缓存
            this.proxyTypes.put(cacheKey, proxy.getClass());
            return proxy;
        }
        // 放入通知缓存
        this.advisedBeans.put(cacheKey, Boolean.FALSE);
        return bean;
    }
}