把实际地址写入cs文件中,不要暴露在外,或者加密url
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//download.aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
String fileUrl = Request.QueryString["file"].Trim().Replace("~", "");
string DownloadFileName = Server.MapPath("~") + fileUrl;
string filepath = DownloadFileName;
string filename = System.IO.Path.GetFileName(filepath);
Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
Response.Flush();
Response.WriteFile(filepath);
}