/// <summary>
/// 获得一个随机文件路径和随机文件名 如:2008/9/18/3/34916af4-53a2-4bb3-833a-f125d5bcafca3.gif
/// </summary>
/// <param name="ext">文件的扩展名如:.gif</param>
/// <returns>返回随机文件路径和名称</returns>
public static string GetRandomFileName(string ext)
{
DateTime now = DateTime.Now;
if (!string.IsNullOrEmpty(ext) && ext[0] != '.') ext = "." + ext;
return string.Format("{0}/{1}/{2}/{3}/{4}{5}", now.Year, now.Month, now.Day, now.Hour, Guid.NewGuid().ToString(), ext);
}
newfile = GetRandomFileName(Path.GetExtension(PostedFile.FileName));
string path = Path.GetDirectoryName(newfile);
if (!Directory.Exists(path)) Directory.CreateDirectory(path);