Spring - Bean 创建中的奇怪错误

知道为什么我会收到此异常吗？

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myService' defined in class path resource [context.xml]: Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type [$Proxy54 implementing org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised,net.sf.cglib.proxy.Factory,org.springframework.beans.factory.InitializingBean] to required type [com.mycompany.service.dao.MyDAO] for property 'myDAO'; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type [$Proxy54 implementing org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised,net.sf.cglib.proxy.Factory,org.springframework.beans.factory.InitializingBean] to required type [com.mycompany.service.dao.MyDAO] for property 'myDAO': no matching editors or conversion strategy found
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:480)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:671)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:610)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(AutowiredAnnotationBeanPostProcessor.java:499)
    ... 36 more
Caused by: java.lang.IllegalArgumentException: Cannot convert value of type [$Proxy54 implementing org.springframework.aop.SpringProxy,org.springframework.aop.framework.Advised,net.sf.cglib.proxy.Factory,org.springframework.beans.factory.InitializingBean] to required type [com.mycompany.service.dao.MyDAO] for property 'myDAO': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:231)
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:138)
    at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:386)
... 62 more

我怀疑如果ProdMiscDAO是一个接口（是吗？），你不会有这个错误。我相信您可能有一个类在底层使用 cglib 进行代理、执行魔法等，最终它无法安全地转换为 setter 或构造函数中的参数。尝试对接口进行编程，看看错误是否消失。

Update: ProdMiscDAO不是一个接口。这是一个扩展的类SqlMappedClientDaoSupport.

鉴于此，我建议尝试以下方法：

1. Rename ProdMiscDAO to SqlMappedProdMiscDAO.
2. 从中提取接口SqlMappedProdMiscDAO named ProdMiscDAO (e.g. "class SqlMappedProdMiscDAO implements ProdMiscDAO")
3. 浏览所有使用的代码SqlMappedProdMiscDAO并将其更改为使用ProdMiscDAO.
4. 配置spring实例化一个SqlMappedProdMiscDAO，将其连接到所有需要它的类。

这允许您的 DAO 实现仍然可以扩展SqlMappedClientDaoSupport而且还要有一个接口。将所有类切换为使用接口而不是类后，Spring 将不必使用 cglib 来代理您的 DAO，并且错误应该消失。