[HttpPost]
        public ActionResult GetData(int? id)
        {
            JsonSerializerSettings settings = new JsonSerializerSettings();
            //EF Core中默认为驼峰样式序列化处理key
            //settings.ContractResolver = new CamelCasePropertyNamesContractResolver();
            //使用默认方式，不更改元数据的key的大小写
            settings.ContractResolver = new DefaultContractResolver();
            return Json(bll.GetData(id),settings);
        }

   public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<HomeBll>();
            services.AddTransient<ProductBll>();
            //全局配置Json序列化处理
            services.AddMvc().AddNewtonsoftJson(options =>
            {
            //忽略循环引用
            options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
            //不使用驼峰样式的key
            options.SerializerSettings.ContractResolver = new DefaultContractResolver();
            //设置时间格式
            options.SerializerSettings.DateFormatString = "yyyy-MM-dd";
             });
        }