根据对应规格更新规格对应数量，库存

/**
      * 减库存
      * @param json 商品规格id 和 数量 json [{"standardid":"79","count":"5"},{"standardid":"81","count":"3"},{"standardid":"82","count":"2"},{"standardid":"83","count":"2"}]
      **/
     @requestmapping(value = "/updatereducestocks.json", method = requestmethod.get)
     @responsebody
     public integer updatereducestocks(string json) {
         hashmap<string , object> map = new hashmap<>();
         net.sf.json.jsonarray jsonarr = net.sf.json.jsonarray.fromobject(json);
         string standardid[] = new string[jsonarr.size()];
         string count[] = new string[jsonarr.size()];
         for (int i = 0; i < jsonarr.size(); i++) {
             standardid[i] = jsonarr.getjsonobject(i).getstring("standardid");
             count[i] = jsonarr.getjsonobject(i).getstring("count");
         }
         for (int i = 0; i < standardid.length; i++) {
             system.out.print("规格id  "+standardid[i]+" ");
             system.out.print("数量 "+count[i]);
             system.out.println();
             integer result = groupgoodsservice.updatereducestocks(parseint(standardid[i]), parseint(count[i]));
         }

         return 1;
}

service:

//减库存
integer updatereducestocks(integer standardid,integer count);

mapper.xml

<!--减库存-->1,0表示按顺序插入，不然不能插入多个或者改配置
<update id="updatereducestocks" parametertype="map">
   update standard set stock = stock-#{1} where standard_id = #{0}
</update>