.NET MVC 文件上传下载

public class FileController : Controller
    {
        //
        // path: /File/Upload

        public ActionResult Upload() {
            ActionResult result = View("UploadFile");
           
            HttpPostedFileBase uploadFile = Request.Files["upload"];
            if(null != uploadFile){
                string filePath =  uploadFile.FileName;
               string fileName =  Path.GetFileName(filePath);
               string uploadPath = HttpContext.Server.MapPath("../Upload/")+fileName;
               uploadFile.SaveAs(uploadPath);

               return RedirectToAction("ListFiles", "File");
            }
            return result;
        }

        public ActionResult ListFiles() {
            string filePath = Server.MapPath("../Upload");
            string[] fileNames = Directory.GetFiles(filePath);
            for (int i = 0; i < fileNames.Length;i++ )
            {
                fileNames[i] = Path.GetFileName(fileNames[i]);
            }
            ViewData["fileNames"] = fileNames;
            return View("ListFile");
        }

 

        public ActionResult Down(string fileName)
        {
           //文件下载
            string fn = Request.Url.ToString();
            string filePath = Server.MapPath("../../Upload")+"\\"+fileName;
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            Response.ContentEncoding = Encoding.UTF8;
            Response.AppendHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName, Encoding.UTF8));
           // Response.AppendHeader("Content-Length", fInfo.Length.ToString());
            Response.WriteFile(filePath);
            return null;
        }

    }