import org.apache.ibatis.session.ResultContext;
import org.apache.ibatis.session.ResultHandler;

import java.util.HashMap;
import java.util.Map;

/**
 * @Desc
 * @Creator Hardy
 * @Create_Date 2022/3/4 9:40
 * @Updater
 * @Update_Date
 **/
public class MapResultHandler implements ResultHandler<Map> {
    private final Map<String, String> mappedResults = new HashMap();

    @Override
    public void handleResult(ResultContext resultContext) {
        Map<String, String> m = (Map) resultContext.getResultObject();
        mappedResults.put(m.get("key"), m.get("value"));
    }

    public Map getMappedResults() {
        return mappedResults;
    }
}

dao层 

void getMixingPlantProductionSummary() String devSNs, MapResultHandler mapResultHandler);

引用

MapResultHandler handler = new MapResultHandler();
xxxDao.getMixingPlantProductionSummary(orgId, devSNs, handler);
Map resultMap = handler.getMappedResults();

mapper.xml

<resultMap id="mapResult" type="java.util.HashMap">
    <result property="key" column="name"/>
    <result property="value" column="count"/>
</resultMap>

<select id="getMixingPlantProductionSummary" resultMap="mapResult">
    SELECT
    gsom.intensity_level AS name,
    SUM(gsom.quantity) AS count
    FROM
    gt_szls_out_master gsom
    <where>
        <if test="orgId != null">
            and gsom.org_id = #{orgId}
        </if>

        <if test="devSNs != null">
            and gsom.dev_sn in (#{devSNs})
        </if>
    </where>
    GROUP BY gsom.intensity_level
</select>

注意：

1、xxxDao.java中定义的接口返回值类型必须是void，如上面void getMixingPlantProductionSummary()

2、MyBatis.xml中定义的resultMap返回值类型是HashMap，其里面定义的两个result中的key要与MapResultHandler.java中代码mappedResults.put(m.get("key"), m.get("value"))保持一致；其value属性必须和Mybatis.xml中sql的返回值名称一致

3、Map resultMap = handler.getMappedResults();中的resultMap就是我们一开始讲到的前端需要的数据类型