Type interface service.UserImp is not known to the MapperRegistry.

MyBatis显示错误：

org.apache.ibatis.binding.BindingException: Type interface service.UserImp is not known to the MapperRegistry.

原因：

关系映射文件的命名空间出错

<mapper namespace="***">

应命名为接口地址：

<mapper namespace="service.UserImp">