int splitNum =(int) Math.ceil( (float) ids.length/999); //切片數(shù)量
      List<String> itemIdList = new ArrayList<>(Arrays.asList(ids));
      List<List<String>> splitList = averageAssign(itemIdList, splitNum);
      for (List<String> list : splitList) {
       param.put("itemIds",list);
       List<Map<Object, Object>> itemStatisticsList = iProcessExtMapper.getItemStatisticsList(param);
       result.addAll(itemStatisticsList);
      }

 public static <T> List<List<T>> averageAssign(List<T> source,int n){
  List<List<T>> result=new ArrayList<List<T>>();
  int remaider=source.size()%n;  //(先計(jì)算出余數(shù))
  int number=source.size()/n;  //然后是商
  int offset=0;//偏移量
  for(int i=0;i<n;i++){
   List<T> value=null;
   if(remaider>0){
    value=source.subList(i*number+offset, (i+1)*number+offset+1);
    remaider--;
    offset++;
   }else{
    value=source.subList(i*number+offset, (i+1)*number+offset);
   }
   result.add(value);
  }
  return result;
 }

i.id in     
 <foreach collection="itemIds" index="index" item="item" open="(" close=")">
 <if test="index != 0">
   <choose>
   <when test="index % 1000 == 999"> ) OR ID IN( </when>
                 <otherwise>,</otherwise>
   </choose>
 </if>
   #{item}
 </foreach> 

ID IN（ids[0],ids[1]+...+ids[998]）OR ID IN (ids[999],ids[1000],...ids[max])

<select id="getByDirIds" parameterType="string" resultMap="dirDocLinkMap">
        SELECT
        <include refid="columns"/>
        FROM KM_DIR_DOC_LINK T
        WHERE T.DIR_ID IN
        <foreach collection="array" index="index" open="(" close=")" item="item" separator=",">
            <if test="(index % 1000) == 999">NULL) OR T.DIR_ID IN (</if>#{item}
        </foreach>
    </select>

<foreach collection="array" item="item" index="index" open="(" close=")" separator=",">
                <if test="(index % 999) == 998"> NULL ) OR DOC.ID IN (</if>#{item}
            </foreach>