声明需要暴露的服务接口时，说创建bean出错，是什么原因？

Error creating bean with name 'cn.e3mall.service.ItemService'

Cannot resolve reference to bean 'itemServiceImpl' while setting bean property 'ref';
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No bean named 'itemServiceImpl' is defined

声明需要暴露的服务接口时，说创建bean出错，是什么原因？

Error creating bean with name 'cn.e3mall.service.ItemService'

Cannot resolve reference to bean 'itemServiceImpl' while setting bean property 'ref';
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No bean named 'itemServiceImpl' is defined