using System;using System.IO;using System.Net;using System.Net.Http;using System.Net.Http.Headers;using JYRS.Util;namespace JYRS.Utils{  public class FileHelper  {    /// <summary>    /// 將文件名解析成文件的上傳路徑    /// </summary>    /// <param name="fileName">文件名</param>    /// <param name="path">文件路徑</param>    /// <returns path>文件在服務器上的路徑</returns>    public static String transPath(string fileName, string path)    {      createDir(path)；      //取服務器時間+8位隨機碼作為部分文件名，確保文件名無重復      string nowStr = DateTime.Now.ToString("yyyyMMddhhmmssff") + Global.CreateRandomCode(8);      // 去掉后綴的文件名      string fileNameStr = fileName.Substring(0, fileName.LastIndexOf("."));      // 文件后綴      String suffix = fileName.Substring(fileName.LastIndexOf(".") + 1);      if (fileName.Trim() != "")      {        // 如果名稱不為"",說明該文件存在，否則說明該文件不存在        path += "//" + fileNameStr + nowStr + "." + suffix;// 定義上傳路徑      }      return path;    }    /// <summary>    /// 創建文件目錄    /// </summary>    /// <param name="root">根目錄</param>    /// <returns ></returns>    private static void createDir(String root)    {      // 檢查目錄      if (!Directory.Exists(System.Web.HttpContext.Current.Server.MapPath(root)))      {        Directory.CreateDirectory(System.Web.HttpContext.Current.Server.MapPath(root));      }    }    /// <summary>    /// 根據文件在服務器上的路徑下載文件，此處采用的是WebAPI的方式進行文件下載，下載成功后可自定義文件的保存路徑    /// </summary>    /// <param name="fileName">文件名</param>    /// <param name="path">文件路徑</param>    /// <returns></returns>    public static HttpResponseMessage download(string fileName, string path)    {      try      {        var stream = new FileStream(path, FileMode.Open);        HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);        response.Content = new StreamContent(stream);        response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");        response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")        {          FileName = fileName        };        return response;      }      catch      {        return new HttpResponseMessage(HttpStatusCode.NoContent);      }    }  }}

[HttpGet]public HttpResponseMessage UploadAndDownload(){  //文件上傳到服務器上的根目錄  string root = System.Web.Hosting.HostingEnvironment.MapPath(@"~/upload");  string fileName = "測試.docx";  //解析文件在服務器上的上傳路徑  string path = FileHelper.transPath(fileName, root);  //獲取要上傳的文件  var files = HttpContext.Current.Request.Files;  HttpPostedFile file = HttpContext.Current.Request.Files[0];  //保存文件  file.SaveAs(System.Web.HttpContext.Current.Server.MapPath(path));  //下載word文件  return FileHelper.download(fileName, path);}

<a href="http://localhost:60179/api/CeshiController/UploadAndDownload" rel="external nofollow" "> 導出 </a>