教学典型案例06.没有复用思想

Posted 2023-03-10 爱吃芋圆的兔子

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了教学典型案例06.没有复用思想相关的知识，希望对你有一定的参考价值。

一：背景介绍

反例1

反例2

二：思路&方案

反例一

两个查询在线人员的接口我们可以使用一个接口进行实现，两个接口的区别主要是在于入参不一致，我们可以通过使用mybatis的动态SQL进行实现。

优化代码

Controller层

    @PostMapping("/queryCourseContent")
    public List<CourseContentEntity> queryCourseContent(@RequestBody CourseContentEntity courseContent)
        return iCourseContentService.queryCourseContent(courseContent);

IService层

List<CourseContentEntity> queryCourseContent(CourseContentEntity courseContent);

ServiceImpl层

    @Resource
    CourseContentMapper courseContentMapper;

    @Override
    public List<CourseContentEntity> queryCourseContent(CourseContentEntity courseContent) 
        return courseContentMapper.queryCourseContentRecord(courseContent);

Mapper层

	//通用查询语句
    List<CourseContentEntity> queryCourseContentRecord(CourseContentEntity courseContentEntity);

Mapper.xml

<select id="queryCourseContentRecord" resultMap="courseContentMap">
        SELECT id,course_assembly_id,assembly_content,create_time,created_id,created_by,update_time,updated_id,updated_by
        FROM  tar_course_content_info
        WhERE
        is_delete=0
        <if test="id != null"> and id = #id </if>
        <if test="courseAssemblyId != null">and course_assembly_id = #courseAssemblyId</if>
        <if test="assemblyContent != null">and assembly_content = #assemblyContent</if>
        <if test="createdBy != null">and created_by = #createdBy</if>
        <if test="updatedBy != null">and updated_by = #updatedBy</if>
        <if test="remark != null">and remark = #remark</if>
    </select>

测试结果

Body中什么都不传，查出来的所有课程

Body中传入参数，查出来的是某个人创建的课程

反例二

将course_id和class_id抽出来作为公共数据使用

优化代码

优化前

		select id,
        user_id,
        user_name,
        questionnaire_id,
        activity_name,
        course_id,
        class_id,
        user_answer,
        start_time,
        update_time,
        remark,
        is_delete
        from
        `arpro_user_answer`
        <where>
            <choose>
                <when test="id !='' and id != null">
                    and id=#id
                </when>
                <when test="user_answer !='' and user_answer != null">
                    user_answer=#user_answer
                    and course_id = #course_id
                    and class_id = #class_id
                </when>
                <when test="questionnaire_id !='' and questionnaire_id != null">
                    and questionnaire_id=#questionnaire_id
                    and course_id = #course_id
                    and class_id = #class_id
                </when>
                <otherwise>
                    and course_id = #course_id
                    and class_id = #class_id
                    and is_delete = 0
                </otherwise>
            </choose>
        </where>
    </select>

优化后

        select id,
        user_id,
        user_name,
        questionnaire_id,
        activity_name,
        course_id,
        class_id,
        user_answer,
        start_time,
        update_time,
        remark,
        is_delete
        from
        `arpro_user_answer`
        <where>
            course_id = #course_id
            and class_id = #class_id
            and is_delete = 0
            <choose>
                <when test="id !='' and id != null">
                    and id=#id
                </when>
                <when test="user_answer !='' and user_answer != null">
                    user_answer=#user_answer
                </when>
                <when test="questionnaire_id !='' and questionnaire_id != null">
                    and questionnaire_id=#questionnaire_id
                </when>
            </choose>
        </where>
    </select>