.net 下实现下载

System.IO.FileInfo file = new System.IO.FileInfo(Server.MapPath("~/upFile/abc.rar"));
        Response.Clear();
        Response.AddHeader("Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(file.Name));

        Response.AddHeader("Content-Length", file.Length.ToString());
        Response.ContentType = "application/octet-stream";
        Response.WriteFile(file.FullName);
        Response.End(); 

把fileInfo的参数改为数据库中读出来的下载路径即可