如何在 C# 中的按鈕的 onClick 事件上下載文件？

Question

我試圖在 C# 中我的按鈕的 onClick 事件上下載一個文件，有人知道這方面的任何信息嗎？

好的，對於那些希望我在 Visual Studio 2015 windows 窗體 c# 中工作更具體一點的人。

Answer 1

如果您使用的是 MVC，那么您可以嘗試以下代碼，它對我有用：

#region Download File ==>
        public ActionResult downloadfile(string Filename, string MIMEType)
        {
            try
            {
                string file_name = "/Files/EvidenceUploads/" + Filename;
                string contentType = "";
                //Get the physical path to the file.
                string FilePath = Server.MapPath(file_name);

                string fileExt = Path.GetExtension(file_name);

                contentType = MIMEType;

                //Set the appropriate ContentType.
                Response.ContentType = contentType;
                Response.AppendHeader("content-disposition", "attachment; filename=" + (new FileInfo(file_name)).Name);

                //Write the file directly to the HTTP content output stream.
                Response.WriteFile(FilePath);
                Response.End();
                return View(FilePath);
            }
            catch
            {
                Response.End();
                return View();
                //To Do
            }

        }
        #endregion

如果您不使用MVC，請參考以下代碼：

#region Download File ==>
        public void downloadfile(string Filename, string MIMEType)
        {
            try
            {
                string file_name = "/Files/EvidenceUploads/" + Filename;
                string contentType = "";
                //Get the physical path to the file.
                string FilePath = Server.MapPath(file_name);

                string fileExt = Path.GetExtension(file_name);

                contentType = MIMEType;

                //Set the appropriate ContentType.
                Response.ContentType = contentType;
                Response.AppendHeader("content-disposition", "attachment; filename=" + (new FileInfo(file_name)).Name);

                //Write the file directly to the HTTP content output stream.
                Response.WriteFile(FilePath);
                Response.End();

            }
            catch
            {
                Response.End();

                //To Do
            }

        }
        #endregion

希望對你有幫助。

Answer 2

首先，問題太寬泛（未指定是桌面還是Web應用程序）。 讓我們建議您指的是 Winforms，然后快速回答是 DownloadFileAsync（異步以保持用戶界面的交互性）：

  private void Download_Click(object sender, RoutedEventArgs e)
   {
      using (WebClient wc = new WebClient())
      {
         wc.DownloadProgressChanged += wc_DownloadProgressChanged;
         wc.DownloadFileAsync(new System.Uri("http://url"),
          "Result location");
      }
   }

有一個進度條是個好主意：

   void wc_DownloadProgressChanged(object sender,  DownloadProgressChangedEventArgs e)
   {
      progressBar.Value = e.ProgressPercentage;
   }

Answer 3

使用 ASP.NET MVC 我在控制器中使用以下內容從 content/Audiofile 文件夾返回一個文件。

 /// <summary>
 /// The download action returns the file as a File download.
 /// </summary>
 /// <param name="filename"></param>
 /// <returns></returns>
 [AllowAnonymous]
 public FilePathResult Download(String filename)
 {
    String myfile = Path.Combine(HttpContext.Server.MapPath("~/Content/audiofiles/"), filename);
    return File(myfile, System.Net.Mime.MediaTypeNames.Application.Octet, filename);
 }