Java Mapper实现分页查询

Mapper.java定义方法

    List<Object> eventList_Done(
            @Param("pageNo") Integer pageNo,
            @Param("pageSize") Integer pageSize
    );

Mapper.xml里面,
先定义两个ResultMap，下面会用到

    <resultMap id="OneMoreResultMap" type="java.util.LinkedHashMap"/>
    <resultMap id="QueryRecordCountMap" type="java.util.LinkedHashMap"/>

然后就是查询的SQL语句

  <select id="eventList_toDo" resultMap="OneMoreResultMap,QueryRecordCountMap">
        select
        SQL_CALC_FOUND_ROWS
        t.ID AS eventId,
            t.NAME AS eventName
        from tbl_event_info t   
        where t.ID is not null 
        LIMIT ${(pageNo-1)*pageSize}, #{pageSize};
        SELECT FOUND_ROWS() AS total;
    </select>

注意重点是上面代码里面的
SQL_CALC_FOUND_ROWS
还有
SELECT FOUND_ROWS() AS total;
这两句一定要加上。

最后，controller里面调用service或者mapper方法的时候，要这么取值：

       List<Object> resultList=eventInfoService.
                getEventList_Done(pageNo,pageSize);

        List<LinkedHashMap<String,Object>> listDatas= (List<LinkedHashMap<String, Object>>) resultList.get(0);
        List<LinkedHashMap<String,Object>> totalMaps= (List<LinkedHashMap<String, Object>>) resultList.get(1);

        Page<LinkedHashMap<String,Object>> page=new Page<>(pageNo,pageSize);
        page.setRecords(listDatas);

        LinkedHashMap<String,Object> totalMap=totalMaps.get(0);
        page.setTotal((Long) totalMap.get("total"));

        return AjaxResult.success(page);