响应 TransmitFile - 什么也没发生

Question

帮助 Response.TransmitFile

发帖前，我在这里搜索了几个类似的帖子

Trouble with Response.WriteFile / Response.BinaryWrite / Response.TransmitFile (ASP.NET)

解决方案包括Response.End();

嗯，我已经添加了最后一行，但仍然没有发生任何事情。

我什至在 ASPX 页面的正文中包含了一个 <asp:Label ID="lblErrMsg" runat="server" />，但也没有写入任何内容。

public void DownloadFile(string nameOnly) {
  if (!String.IsNullOrEmpty(nameOnly)) {
    lblErrMsg.Text = "Transfer request for " + nameOnly;
    string filename = Server.MapPath(nameOnly);
    try {
      if (!String.IsNullOrEmpty(filename)) {
        Response.Buffer = true;
        Response.Clear(); // clear the buffer
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        if (-1 < filename.IndexOf(".avi")) {
          Response.ContentType = "video/x-msvideo";
          lblErrMsg.Text = "Content Type Set to Video.";
        } else if (-1 < filename.IndexOf(".pdf")) {
          Response.ContentType = "Application/pdf";
          lblErrMsg.Text = "Content Type Set to PDF.";
        } else if (-1 < filename.IndexOf(".rar")) {
          Response.ContentType = "Application/x-rar-compressed";
          lblErrMsg.Text = "Content Type Set to RAR.";
        } else {
          Response.ContentType = "Application/octet-stream";
          lblErrMsg.Text = "Content Type Set to Octet Steam.";
        }
        FileInfo file = new FileInfo(filename);
        Response.AddHeader("Content-Disposition", "attachment; filename=" + nameOnly);
        Response.AddHeader("Content-Length", file.Length.ToString());
        lblErrMsg.Text = "Content Headers added.";
        Response.TransmitFile(file.FullName);
        lblErrMsg.Text = "Transfer Completing...";
        Response.End();
        lblErrMsg.Text = "Transfer Complete.";
      } else {
        throw new Exception(string.Format("Server was unable to locate file \"{0}\".", nameOnly));
      }
    } catch (Exception err) {
      lblErrMsg.Text = err.Message;
    }
  }
}

• 有人知道我做错了什么吗？

就像我说的，lblErrMsg.Text 是空白的，但没有显示下载对话框，而且似乎什么也没有发生。

更新：

我正在与 Aristos 合作。我使用他的建议修改了我的方法，但我的示例下载文件仍然没有显示：

private string Download(string nameOnly) {
  string outputLine = null;
  if (!String.IsNullOrEmpty(nameOnly)) {
    string filename = Server.MapPath(nameOnly);
    if (!String.IsNullOrEmpty(filename)) {
      try {
        Response.Buffer = false;
        Response.Clear(); // clear the buffer
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        if (-1 < filename.IndexOf(".avi")) {
          Response.ContentType = "video/x-msvideo";
        } else if (-1 < filename.IndexOf(".pdf")) {
          Response.ContentType = "Application/pdf";
        } else if (-1 < filename.IndexOf(".rar")) {
          Response.ContentType = "Application/x-rar-compressed";
        } else {
          Response.ContentType = "Application/octet-stream";
        }
        FileInfo file = new FileInfo(filename);
        Response.AddHeader("Content-Disposition", "attachment; filename=" + nameOnly);
        Response.AddHeader("Content-Length", file.Length.ToString());
        Response.TransmitFile(file.FullName);
      } catch (Exception err) {
        outputLine = err.Message;
      } finally {
        Response.Flush();
      }
    } else {
      outputLine = string.Format("Server was unable to locate file \"{0}\".", nameOnly);
    }
  }
  if (String.IsNullOrEmpty(outputLine)) {
    Response.Redirect("~/Default.aspx");
  }
  return outputLine;
}

Answer 1

尝试了解您有一个返回浏览器数据的管道。

在您的代码中，您的行为就像您将两种数据发送回，一种发送到页面，另一种发送到下载数据 - 但实际上您不能这样做。就像您尝试在两个不同的文件上写入 - 将一个流打开到一个文件。

所以选择以太发送文件，以太更新页面。

我在这里描述了我认为下载文件的最佳方式：
Side actions not happening after Response.WriteFile()
What is the best way to download file from server
Error handling when downloading file from ASP.NET Web Handler (.ashx)