FileContentResult 类下载二进制文件详解

public class FileContentResult : Microsoft.AspNetCore.Mvc.FileResult

/// <summary>
        /// 下载流程上传的文件跳过流程系统直接下载
        /// </summary>
        /// <param name="affterOid">售后主键</param>
        /// <param name="flieName">文件名称</param>
        /// <returns></returns>
        public FileContentResult FilePathDownload(string affterOid,string flieName)
        {
            try
            {
                HttpContext.Response.AppendHeader("Access-Control-Allow-Origin", "*");//支持跨域请求 
                string sql = "SELECT seqNO FROM dbo.*** WHERE Affter_EntryOID = '" + affterOid + "'";
                string seqNO = "",  ContentType ="";
                byte[] buffer = null;
                var re = erpReadService.GetDataTable(sql);
                if (re.Rows.Count != 0)
                {
                    seqNO = re.Rows[0]["seqNO"].ToString();
                }
                //Byte[] buffer = BlobStorage.DownloadFile(pathName);
                string sqlH3 = "SELECT a.Content Content,a.ContentType ContentType FROM *** a LEFT JOIN *** b ON a.BizObjectId = b.BizObjectId WHERE b.SequenceNo = '" + seqNO + "' and a.FileName = '" + flieName + "'";
                var resH3 = H3Service.GetDataTable(sqlH3);
                if (re.Rows.Count != 0)
                {
                    buffer = (byte[])resH3.Rows[0]["Content"];
                    ContentType = resH3.Rows[0]["ContentType"].ToString();
                }
                FileContentResult result = new FileContentResult(buffer, ContentType);
                return result;
            }
            catch (Exception ex)
            {
                // log error
            }
            // how to handle if file is not found?
            return new FileContentResult(new byte[] { }, "PDF");
        }