spring-boot-realworld-example-app/src/main/resources/mapper/UserReadService.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="io.spring.infrastructure.mybatis.readservice.UserReadService">
    <select id="findByUsername" resultType="io.spring.application.data.UserData">
        select * from users where username = #{username}
    </select>
    <select id="findById" resultType="io.spring.application.data.UserData">
        select * from users where id = #{id}
    </select>
</mapper>