mybatis出错Error parsing Mapper XML Error parsing Mapper XML Cannot find class

: 
### Error building SqlSession.

### The error may exist in com/mybatis/test5/ 

### Cause: : Error parsing SQL Mapper Configuration. Cause: : Error parsing Mapper XML. Cause: : Error resolving class . Cause: : Could not resolve type alias 'Classes'.  Cause: : Cannot find class: Classes

中

<mapper namespace=".">

<select parameterType="int" resultType="Classes">
   SELECT * FROM class WHERE c_id=#{id};
</select>

</mapper>

resultType="Classes"应该写包含路径的全类名 resultType="."