防止文件重名方法

protected void btnUpload_Click(object sender, EventArgs e)
    {
if (upload1.HasFile)
        {
            HttpPostedFile file = upload1.PostedFile;
string extension = Path.GetExtension(file.FileName);
string fileName = DateTime.Now.ToString("yyyyMMddhhmmss") + extension;
string path = Server.MapPath("uploads");
string savePath = Path.Combine(path, fileName);
//Response.Write(savePath);
            string imagePath = "uploads/" + fileName;
            file.SaveAs(savePath);
if (extension.Equals(".bmp") || extension.Equals(".jpg") || extension.Equals(".gif"))
            {
                Image1.ImageUrl = imagePath;
            }
        }
    }

1.重新命名成yyyyMMddhhmmss＋后缀名的文件就行了。
2.Guid
3.yyyyMMddhhmmss+原文件名