产生当前时间+随机数的文件名的方法

 public static string GetNewFileName(string FileName)
    {//跟据文伯名产生一个由时间+随机数组成的一个新的文件名
        string newfilename = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString()
        + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString()
        + DateTime.Now.Second.ToString() + DateTime.Now.Minute.ToString()
        + DateTime.Now.Millisecond.ToString()
            //+ rand.Next(1000).ToString()
        + FileName.Substring(FileName.LastIndexOf("."), FileName.Length - FileName.LastIndexOf("."));
        return newfilename;
    }
调用：

 string newfilename = GetNewFileName(FileUpload1.FileName);
 fileUpload.SaveAs(p.Server.MapPath("DownLoadFile/" + newfilename));