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标题: 【上海校区】Spring循环依赖问题修复 [打印本页]

作者: 梦缠绕的时候 时间: 2018-12-24 14:52
标题: 【上海校区】Spring循环依赖问题修复

Spring循环依赖问题修复
拆分的时候，把错误都处理完后，准备把工程起起来，发现弹簧的循环依赖问题。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，百度了一下这个错误

beanFactory.setAllowRawInjectionDespiteWrapping(true);

看网上说这个配置了，对于循环依赖的这个错误就会解决掉。但是在两个工程里搜索了一下都没有发现这个配置过。
于是只能调试进去看看
2.调查查看分析
2.1 spring引用的bean和注入的bean不一致导致的这个错误
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调试
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修改了返回的结果

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。需要预处理代理。
往远工程里加了这个annatation，但是调试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
但是再调试到postProcessAfterInitialization的时候，发现包就是不对
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
解决方法
干掉一个AnnotationAwareAspectJAutoProxyCreator，这个循环依赖的错误，就处理了

作者: 不二晨 时间: 2018-12-26 09:59

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