Proxy cannot be cast to server.impl.ProductserviceImpl 解决方法!

我在DAO层建立了ProductMgmtImpl类，在SERVICE层建立了ProductserviceImpl类，然后将其配置到spring中的配置文件中
<!-- service -->
<bean id="productservice"
class="service.impl.ProductserviceImpl">
<property name="dao"
ref="ProductMgmtDAOImpl">
</property>
</bean>
然后测试ProductserviceImpl类时（测试代码如下）
ApplicationContext factory = new ClassPathXmlApplicationContext(
"applicationContext.xml");
private ProductserviceImpl Productservice= (ProductserviceImpl) factory.getBean("ProductserviceImpl ");

总报如下错误
ClassCastException: Proxy cannot be cast to server.impl.ProductserviceImpl
请问为什么从配置文件中读取ProductserviceImpl类时，不能转换成ProductserviceImpl类呢？
    非常感谢！


------解决方法--------------------------------------------------------
private ProductserviceImpl Productservice= (ProductserviceImpl) factory.getBean("productservice");

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------解决方法--------------------------------------------------------
<bean id="productservice"
class="service.impl.ProductserviceImpl">

private ProductserviceImpl Productservice= (ProductserviceImpl) factory.getBean("ProductserviceImpl ");
?

<bean id="productservice"
class="service.impl.ProductserviceImpl">

private ProductserviceImpl Productservice= (ProductserviceImpl) factory.getBean("productservice");