mybatis in查询条件过长的解决方案

int splitNum =( int ) Math.ceil( ( float ) ids.length/ 999 ); //切片数量

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;  //(先计算出余数)

  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 >