UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="UserMapper">
    <select id="selectUser" resultType="com.cesgroup.pojo.User">
        select * from mybatis where id = #{id}
    </select>
</mapper>