asp.net mvc return file result

　　asp.net mvc返回文件：

public ActionResult ExportReflection(string accessToken)

        {

            var reflections = GetCmsReflectionList(accessToken);



            var sb = new StringBuilder();

            sb.AppendFormat("{0,-10},{1,-10},{2,-10},{3,-10},{4,-10},{5,-100},{6,-100},{7,-50}", "创建者身份", "创建者姓名", "教练打分", "所属能力", "主题", "内容", "参与者", "创建时间");

            sb.AppendLine();

            foreach (var r in reflections)

            {

                var creatorRole = r.CreatorRole == 0?"学员":"教练";

                sb.AppendFormat("{0,-10},{1,-10},{2,-10},{3,-10},{4,-10},{5,-100},{6,-100},{7,-50}", 

                    creatorRole, 

                    r.CreatorUserName,

                    r.ScoreFromCoach,

                    r.CompetencyName,

                    r.Subject,

                    r.Content,

                    r.ParticipantsNameString,

                    r.CreatedTime);

                sb.AppendLine();

            }

            //var encoding = Encoding.GetEncoding(936); //gb2312

            var bytes = Encoding.GetEncoding(936).GetBytes(sb.ToString());



            //return File(new MemoryStream(bytes, 0, bytes.Length), "application/csv", "reflections" + DateTime.UtcNow.ToShortDateString() + ".csv");//excel打开csv有乱码

            return File(bytes, "application/csv", "reflections" + DateTime.UtcNow.ToShortDateString() + ".csv");

        }