asp.net使用FileUpload控件上传图片且重命名

if (FileUpload1.HasFile)
{
string filename = FileUpload1.FileName;
//获取上传名字
string fileext = System.IO.Path.GetExtension(filename);
//返回指定图片的后缀
string filenamaes = DateTime.Now.ToString("yyyyMMddHHffss") + fileext;
//获取当前时间
FileUpload1.SaveAs(Server.MapPath(".") + "//Images//" + filenamaes);
//上传到此项目根目录的images文件夹
this.fileup_text.Text = "上传成功!";

}
else
{
this.fileup_text.Text = "你还没选择文件呢!";
}