提示保存文件-MVC

Question

我想向用户提示一个保存对话框。文件类型是 .wav。该操作如下所示

  public ActionResult MergeSelectedRecords(string mergeFileName, List<String> selectedRecords)
    {
       string urlFilePath=GetFilePath(); //get virtual path of file.       

       ControllerContext.HttpContext.Response.AddHeader("content-disposition",        "attachment; filename=" + "cccc");    

       string filePath = ControllerContext.HttpContext.Server.MapPath(urlFilePath);
       return File(filePath, ".wav");
      }

样本文件路径为“http:/localhost:2694/DATA/MERGE/OUT/1/cccc”

但它显示如下所示的错误

'http:/localhost:2694/DATA/MERGE/OUT/1/cccc' is not a valid virtual path. 

这是向用户提示保存文件对话框的正确方法吗？

编辑

有时用户没有可用的文件。所以我只想在 urlFilePath="" 时显示警报。

如果没有可用的文件路径，我如何返回空结果。并向用户发出警报。我想要的东西如下

  public ActionResult MergeSelectedRecords(string mergeFileName, List<String> selectedRecords)
    {
       string urlFilePath=GetFilePath(); //get virtual path of file.       
     if(urlFilePath!="")
      {
       ControllerContext.HttpContext.Response.AddHeader("content-disposition",        "attachment; filename=" + "cccc");    

       string filePath = ControllerContext.HttpContext.Server.MapPath(urlFilePath);
       return File(filePath, ".wav");
      }
     else
      {
           //what i return here? If it possible i only want to display an alert .But the page user viewing cannot refreshed
      } 
      }

Answer 1

您传递给 MapPath 方法的 urlFilePath 参数必须是同一站点内以 ~/ 开头的相对 URL。示例：

public ActionResult MergeSelectedRecords(string mergeFileName, List<String> selectedRecords)
{
    string urlFilePath = "~/Files/ccc.wav";
    string filePath = Server.MapPath(urlFilePath);
    return File(filePath, ".wav", "ccc");
}

如果该网址不属于您网站的一部分，您需要先下载该文件。例子：

public ActionResult MergeSelectedRecords(string mergeFileName, List<String> selectedRecords)
{
    using (var client = new WebClient())
    {
        byte[] file = client.DownloadData("http://foo.com/ccc.wav");
        return File(file, ".wav", "ccc");
    }
}