mapper(StudentDao)

<?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="gu.bao.dao.StudentDao"><!--dao 接口的全限定名称-->
    <select id="selectStudents" resultType="gu.bao.domain.Student"></select>
</mapper>