List<Map<String,String>> maps = todoMapper.seletLineDate();
// 此时的状态是List<Map<String,Object>>
Map<String, String> mapto = new HashMap<>();
for (Map<String, String> map : maps) {
mapto.put(map.get("time"), map.get("number"));
}
// 此时的状态是Map<String,Long>
如果用Map<String,String>接返回值，会报Long转String的类型错误
<select id="seletLineDate" resultType="map">
select COUNT(task_uuid) number, end_date time
from todo
where user_uuid = #{userUuid}
and done = true
and end_date between #{startTime} and #{endTime}
group by end_date
order by end_date
</select>
原因是COUNT返回的Number类型会和Java的Long类型进行匹配
List<Map<String,String>> seletLineDate(String startTime, String endTime, String userUuid);
当Mapper层用Map<String,String>接数据时,仍然返回Map<String,Long>只是明面上是Map<String,String>
修改方法
用Object去接，或者转换COUNT的返回结果，CONVERT(COUNT(task_uuid),CHAR)
PS：
该错误在编辑时不会报错,但是在运行时会报错
