将文件存储在ASP.net网站,然后下载到浏览器

我正在我的电脑上用C#创建一个Excel文件asp.net网站。然后,我想将这个文件保存在web服务器文件中的某个位置,并将该文件发送到浏览器供用户下载。

我已经在dev环境中的本地系统上运行了它,但是我没有得到正确的文件地址。

1. 如何将文件存储在“~\ParentFolder\SubFolder”中\文件.ext".
2. 然后将该文件发送到浏览器供用户下载。

        String outputFile = Utilities.writeToExcelFile("", MapPath(@"~\ReportFiles\TempFiles\DropShipData.xls"), table);

    DownloadFile(outputFile);


       public void DownloadFile(string fname)
{
    string path = fname;
    string name = Path.GetFileName(path);
    string ext = Path.GetExtension(path);
    string type = "";
    // set known types based on file extension  
    if (ext != null)
    {
        switch (ext.ToLower())
        {
            case ".htm":
            case ".html":
            case ".aspx":
            case ".asp":
                type = "text/HTML";
                break;

            case ".xls":
            case ".xlsx":
            case ".csv":
                type = "Application/x-msexcel";
                break;

            case ".pdf":
                type = "Application/pdf";
                break;

            case ".txt":
                type = "text/plain";
                break;

            case ".doc":
            case ".docx":
            case ".rtf":
                type = "Application/msword";
                break;
        }
    }

    Response.AppendHeader("content-disposition",
        "attachment; filename=" + name);

    if (type != "")
        Response.ContentType = type;
    Response.WriteFile(path);
    Response.End();
}