mybatis 批量更新

<update id="batachUpdateFieldChild" parameterType="java.util.List">
   update yryz_field_child c set
   c.designation=
   <foreach collection="list" item="fieldChild" index="index"
       separator=" " open="case c.id" close="end">
       when #{fieldChild.id,jdbcType=INTEGER} then
       #{fieldChild.designation,jdbcType=VARCHAR}
   </foreach>
   ,c.attach_code=
   <foreach collection="list" item="fieldChild" index="index"
       separator=" " open="case c.id" close="end">
       when #{fieldChild.id,jdbcType=INTEGER} then
       #{fieldChild.attachCode,jdbcType=INTEGER}
   </foreach>
   where c.id in
   <foreach collection="list" index="index" item="fieldChild"
       separator="," open="(" close=")">
       #{fieldChild.id,jdbcType=INTEGER}
   </foreach>
</update>

原理等同于:

update yryz_field_child c set
c.designation= case c.id

when id then attachCode

end

where c.id in (id)

eg:

update yryz_field_child c set
c.designation= case c.id

when 1 then 'hello'

when 2 then 'world'

end

where c.id in (1,2)

eg:

update yryz_field_child c
set c.designation= case c.id
   when ? then ?
   when ? then ?
   when ? then ?
   when ? then ?
end
where c.id in ( ? , ? , ? , ? )

public int batachUpdateFieldChild(List<FieldChild> fieldChildList);

    @ResponseBody
   @POST
   @Path("/batachUpdateFieldChild")
   public ResultEntity batachUpdateFieldChild(MergeDto mergeDto){
       String designationStrs=mergeDto.getDesignation();
       String[] designationsBase=designationStrs.split(" ");
       String[] newdesignations=arrayResult(designationsBase);
       int id=0;String designation="";
       List<FieldChild> fieldChildlist=new ArrayList<FieldChild>();
       FieldChild fieldChild=null;
       for(int i=0;i<newdesignations.length;i++){
           String newdesignationsChild=newdesignations[i];
           System.out.println(newdesignationsChild);
           String[] lastdesignationsChild=newdesignationsChild.split(",");
           for(int j=0;j<lastdesignationsChild.length;j++){
               id=Integer.valueOf(lastdesignationsChild[0]);
               fieldChild=new FieldChild();
               designation=lastdesignationsChild[1];
               fieldChild.setId(Long.valueOf(id));
               fieldChild.setAttachCode(mergeDto.getAttachCode());
               fieldChild.setDesignation(designation);
           }
           fieldChildlist.add(fieldChild);

       }
       int countChild=fieldChildService.batachUpdateFieldChild(fieldChildlist);
       String msg="";
       if(countChild>0){
           msg="success";
       }else{
           msg="fail";
       }
       return new ResultEntity(msg,null);
   }

空格进行分割，完了放入array数组中，便利数组存入对象，将对象放入List中

/**
   * 对数组进行去重
   * @param str
   * @return
   */
   public static String[] arrayResult(String[] str){
       String[] array = str;
        Set<String> set = new HashSet<>();
        for(int i=0;i<array.length;i++){
            set.add(array[i]);
        }
        String[] arrayResult = (String[]) set.toArray(new String[set.size()]);
       return arrayResult;
   }