.Net5 WebApi中下载文件（返回FileStreamResult）

• WebApi Code
• Client Code

        /// 

        /// 下载文件   LastUpdateDate：2021-07-14 18:25:03.811  Author：Lingbug
        /// 
        /// 
        [HttpPost, AllowAnonymous]
        public IActionResult DownloadFile()
        {
            //文件地址
            var fileUrl = Request.Form["fileUrl"].ToString();
            //校验
            if (fileUrl.IsNullOrWhiteSpaceString()) throw new ErpFriendlyException("要下载的文件地址不能为空！");
            //文件路径
            string filePath = FileUtil.GetFullPath(fileUrl);
            //校验
            if (!System.IO.File.Exists(filePath)) throw new ErpFriendlyException("要下载的文件不存在！");
            //新文件
            var copyFile = new SaveFileOutput(Path.GetFileName(filePath), SaveFileOutputFileNameTypeEnum.TimeStamp, "UploadFiles", "DownloadFile", "Copy");
            //复制文件
            System.IO.File.Copy(filePath, copyFile.FileFullPath, true);
            //文件名
            var fileName = Request.Form["fileName"].ToString();
            //文件名
            if (fileName.IsNullOrWhiteSpaceString()) fileName = Path.GetFileName(filePath);
            //下载
            return new FileStreamResult(new FileStream(copyFile.FileFullPath, FileMode.Open), "application/octet-stream") { FileDownloadName = fileName.TrimStr() };
        }