.net上传图片

//判断是否选择文件
        if (!FileUpload1.HasFile)
        {
            Response.Write("没有要上传的文件!");
            return;
        }
        string filepath = FileUpload1.PostedFile.FileName;

        int i = filepath.IndexOf(".");
        string fileType = filepath.Substring(i);
        string[] extens = new string[] { ".jpeg", ".bmp", ".png", ".gif", ".jpg" };
        string filename = FileUpload1.FileName;
        if (extens.Contains(fileType))//格式
        {
            string path = HttpContext.Current.Server.MapPath("~/UploadFiles/");
            FileUpload1.PostedFile.SaveAs(path+filename);
        }
        else
        {
            Response.Write("文件格式不正确!");
            return;
        }