get参数2000字符以内，超过就会报请求参数校验失败。
所以要把get改成post
1.后台

 @RequestMapping(value = "/file_F_save", method = RequestMethod.POST)

2.前台js post
注意 params

 export const filesave_F = params => { return Axios.post(`${BASE_PATH2}/user/file_F_save`,   params ).then(res => res.data) }

3.前台代码 params 序列化传参

  var qs = require('qs');
            var params = qs.stringify({
              yichang:this.featuresForm.yichang,
              oilmidu: this.featuresForm.oilmidu,
              zaiheConfirm:this.featuresForm.zaiheConfirm,
              rodmidu: this.featuresForm.rodmidu,
              drop:JSON.stringify(this.dropcheckedList)
            });
            
 filesave_F (params).then(
      
      }