我正在我的项目中实施Spring Security

在我的DAO类中，我正在定义loadUserByUsername

我的课就像

UserDAOImpl.java

@Repository
public class UserDAOImpl {

public UserDetails loadUserByUsername(String name)throws UsernameNotFoundException
{
  //implementation 
}
}

在Spring-security.xml中

<authentication-manager>
        <authentication-provider user-service-ref="UserDAOImpl">
      </authentication-provider>
    </authentication-manager>

但是当我运行程序时出现错误

Error creating bean with name 'org.springframework.security.authentication.dao.DaoAuthenticationProvider#0': Cannot resolve reference to bean 'UserDAOImpl' while setting bean property 'userDetailsService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'UserDAOImpl' is defined

谁能帮我解决这个问题？