MyBatis中foreach与resultMap使用

一、foreach标签

示例代码:

.xml文件java

<select id="getArticle"  resultType="com.my.Article">
    select
    ta.ID, ta.article 
    from t_article ta where 1=1
        <if test="blacklist != null and blacklist.size()>0 ">
        and ta.createrid not in
            <foreach collection="blacklist" index="index" item="item" open="(" separator="," close=")">
            #{item}
            </foreach>
        </if>
</select>

dao层接口web

List<Article> getArticle(@Param("blacklist") List<Long> blackList);

说明

接口传入List类型，使用foreach遍历并查询svg

1. collection 要遍历的集合名 在dao接口中使用@Param注解对应命名
2. index 当前遍历元素下标
3. item 遍历出的数据（集合中存放的数据）
4. open 循环开头以什么字符。 为了符合not in 语法 因此开头使用“（”，结尾使用“）”
5. separator 两次循环之间须要添加的字符，即not in（1,2,3）中的逗号
6. close 遍历结束后要加入的字符 同open标签
7. #{item} 取item的值

二、resultMap

示例代码

.xml文件映射配置ui

<resultMap id="GoodsSizeVo" type="com.my.GoodsSizeVo">
    <result column="images" jdbcType="VARCHAR" property="images" />
    <result column="price" jdbcType="BIGINT" property="price" />
    <result column="goodsName" jdbcType="VARCHAR" property="goodsName" />
    <result column="isCust" jdbcType="INTEGER" property="isCust" />
    <result column="spuId" jdbcType="INTEGER" property="spuId" />
    <collection property="groupAndParamVoList" ofType="com.my.GroupAndParamVo">
      <result column="lable" property="lable"/>
      <result column="sort" property="sort"/>
      <collection property="params" ofType="java.lang.String" javaType="java.util.List">
        <result column="param"/>
      </collection>
    </collection>
</resultMap>

.xml查询语句code

<select id="selectSpuBaseInfo" parameterType="com.my.Spu" resultMap="GoodsSizeVo">
   SELECT
	ts.images,
	ts.price,
	ts.NAME goodsName,
	ts.is_cust isCust,
	ts.id spuId,
	tsg.`name` lable,
	tsg.sort,
	tsp.`name` param
    FROM
        t_spu ts,
        t_spec_group tsg,
        t_spec_param tsp
    WHERE
        ts.id = #{id}
        AND tsg.spuid = ts.id
        AND tsp.spuid = ts.id
        AND tsp.group_id = tsg.id
    order by tsg.sort
  </select>

dao接口xml

GoodsSizeVo selectSpuBaseInfo(Spu spu);

实体类数据格式blog

@Data
public class GoodsSizeVo extends Entity {
    private String images;
    private Integer price;
    private String goodsName;
    private Integer isCust;
    private Long spuId;
    private List<GroupAndParamVo> groupAndParamVoList;
}

@Data
public class GroupAndParamVo{
    private String lable;
    private List<String> params;
    private Integer sort;
}

图例说明