Spring 循环依赖问题fix

拆分的时候，把error都处理完后，准备把工程起起来，发现spring的循环依赖问题。具体问题如下

Bean with name 'userManager' has been injected into other beans [daoAuthenticationProvider] in its raw version as part of a circular reference, but has eventually been wrapped (for example as part of auto-proxy creation). 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.

1. 怀疑配置文件的问题

但是在原工程中并没有这个问题，所以一开始怀疑是配置文件的配置不一样，百度了一下这个error

beanFactory.setAllowRawInjectionDespiteWrapping(true); 

看网上说这个配置了，对于循环依赖的这个error就会解决掉。但是在两个工程里搜索了一下都没有发现这个配置过。
于是只能debug进去看看

2. debug 查看 分析

2.1 spring 引用的bean和注入的bean不一致导致的这个error

由于在原工程里是可以循环引用的，所以对工程和新工程都在初始化这两个循环引用的位置进行了debug
然后发现最后两边走的逻辑不一样的在以下的代码里:

AbstractAutowireCapableBeanFactory.doCreateBean()final String beanName, final RootBeanDefinition mbd, final Object[] args:

...
Object earlySingletonReference = getSingleton(beanName, false);
if (earlySingletonReference != null) {
    if (exposedObject == bean) {
        // 原工程走到了这里
        exposedObject = earlySingletonReference;
    }
    else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
        // 新的有error的bean走到里这里
        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.");
        }
    }
}
...

从这里已经可以看到，是新工程中的 exposedObject 和 bean不一样导致的

而这两者的关系如下面的代码

// Initialize the bean instance.
    Object exposedObject = bean;
    try {
        populateBean(beanName, mbd, instanceWrapper);
        if (exposedObject != null) {
            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);
        }
    }

也就是说exposedObject 在initializeBean 函数之后变掉了

2.2 AnnotationAwareAspectJAutoProxyCreator把返回值修改了

然后发现在applyBeanPostProcessorsAfterInitialization 函数中，AnnotationAwareAspectJAutoProxyCreator修改了返回的result

public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
    if (bean != null) {
        Object cacheKey = getCacheKey(bean.getClass(), beanName);
        if (!this.earlyProxyReferences.contains(cacheKey)) {
            return wrapIfNecessary(bean, beanName, cacheKey);
        }
    }
    return bean;
}

逻辑如上，也就是说earlyProxyReferences 这个里不存在这个cacheKey

2.3 怀疑是自定义的annotaion修改导致

因为函数中，AnnotationAwareAspectJAutoProxyCreator是处理annotaion的相关。需要预处理Proxy。
往远工程里加了这个annatation， 但是debug发现原工程里的这样的annotaion也没有问题

2.4 配置文件里起了两个AnnotationAwareAspectJAutoProxyCreator，才导致了这个问题

看了一下earlyProxyReferences 会在哪一步进行put进入。
发现在Factory.getObject()的时候会调用。然后断点到put的地方，也确实put进入了
但是再debug到postProcessAfterInitialization的时候，发现contains就是不对
然后看了下看了一下earlyProxyReferences的值，发现居然有两个AnnotationAwareAspectJAutoProxyCreator
然后干掉之后确实是可以的

3. 两个AnnotationAwareAspectJAutoProxyCreator 导致这个问题的原因

因为调用actory.getObject() 时. 调用下面的方法，

protected Object getEarlyBeanReference(String beanName, RootBeanDefinition mbd, Object bean) {
        Object exposedObject = bean;
        if (bean != null && !mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
            for (BeanPostProcessor bp : getBeanPostProcessors()) {
                if (bp instanceof SmartInstantiationAwareBeanPostProcessor) {
                    SmartInstantiationAwareBeanPostProcessor ibp = (SmartInstantiationAwareBeanPostProcessor) bp;
                    exposedObject = ibp.getEarlyBeanReference(exposedObject, beanName);
                    if (exposedObject == null) {
                        return exposedObject;
                    }
                }
            }
        }
        return exposedObject;
    }

就会导致两个的AnnotationAwareAspectJAutoProxyCreator的earlyProxyReferences中含有不一样的代理对象

而在最后匹配时的逻辑

public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
            throws BeansException {

        Object result = existingBean;
        for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
            result = beanProcessor.postProcessAfterInitialization(result, beanName);
            if (result == null) {
                return result;
            }
        }
        return result;
    }

第二个AnnotationAwareAspectJAutoProxyCreator 发现earlyProxyReferences 不存在第一个的代理对象的值，返回自己的代理对象，结果导致不一样

4. 解决方法

干掉一个 AnnotationAwareAspectJAutoProxyCreator, 这个循环依赖的error，就处理了