一、异常描述

mybatis报错：org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'com.nowcoder.community.dao.UserMapper.selectByName'.It's likely that neither a Result Type nor a Result Map was specified.

二、解决方法

其实后面已经给出提示It's likely that neither a Result Type nor a Result Map was specified.

在usermapper的xml文件的查询语句中，结果类型忘记声明了-.-

更改如下

<select id="selectByName" resultType="User">
    select <include refid="selectFields"></include>
    from user
    where username = #{username}
</select>

成功