Mybatis——动态sql+字符串匹配导致的判断问题

在mybatis的学习中,狂神建议字符串匹配直接将模糊匹配的符号放在字符串中,如:匹配‘keWord‘,那么实际所使用的参数应该为‘%keyWord%‘

map.put("keyWord","%" + keyWord + "%");

<select id="getUserLikeGaojianList" parameterType="map" resultMap="userLikeGaojianEntity">
    SELECT *
    FROM news_base_gaojian g LEFT JOIN news_base_gaojian_like l ON l.gid=g.gj_id and l.uid = #{uId} and type=2
    <where>
        is_delete = 0 AND gj_user_type = #{userType} AND gj_hash_p = #{gjHashP}
        <if test="tougaoState != null">
            AND gj_tougao_pingtai_num >= #{tougaoState}
        </if>
        <if test="gjType != null">
            AND gj_type = #{gjType}
        </if>
        <if test="keyWord != null ">
            AND ( gj_title LIKE #{keyWord} OR gj_title2 LIKE #{keyWord} OR gj_bianji LIKE #{keyWord} OR gj_laiyuan LIKE #{keyWord} OR gj_excerpt LIKE #{keyWord})
        </if>
        <if test="date1 != null and date2 != null">
            AND gj_lasttime &lt;= #{date1} AND  &gt;= #{date2}
        </if>
    </where>
    LIMIT 0,20
</select>

注意:此时就不能用keyWord != null做为动态sql中test的参数,因为当关键字keyWord为空时,keyWord="%null%"

解决方案:

1. 修改.xml文件

   <select id="getUserLikeGaojianList" parameterType="map" resultMap="userLikeGaojianEntity">
           SELECT *
           FROM news_base_gaojian g LEFT JOIN news_base_gaojian_like l ON l.gid=g.gj_id and l.uid = #{uId} and type=2
           <where>
               is_delete = 0 AND gj_user_type = #{userType} AND gj_hash_p = #{gjHashP}
               <if test="tougaoState != null">
                   AND gj_tougao_pingtai_num >= #{tougaoState}
               </if>
               <if test="gjType != null">
                   AND gj_type = #{gjType}
               </if>
               <if test="keyWord != ‘%null%‘ ">
                   AND ( gj_title LIKE #{keyWord} OR gj_title2 LIKE #{keyWord} OR gj_bianji LIKE #{keyWord} OR gj_laiyuan LIKE #{keyWord} OR gj_excerpt LIKE #{keyWord})
               </if>
               <if test="date1 != null and date2 != null">
                   AND gj_lasttime &lt;= #{date1} AND  &gt;= #{date2}
               </if>
           </where>
           LIMIT 0,20
       </select>

2. 修改service层

   <if test="keyWord != null ">
       AND ( gj_title LIKE #{keyWord} OR gj_title2 LIKE #{keyWord} OR gj_bianji LIKE #{keyWord} OR gj_laiyuan LIKE #{keyWord} OR gj_excerpt LIKE #{keyWord})
       </if>