ASP.NET 文件上传

protected void UploadBtn_Click(object sender, EventArgs e)
    {
        //******************获取文件的扩展名如：（.rar）***************************
        string fileName = this.FileUpload1.PostedFile.FileName;//获取上传文件的名称
        int length = fileName.Length;//获取上传文件的名称的长度
        int intID = fileName.LastIndexOf(".");
        string oldName = fileName.Substring(intID, length - intID);//获得文件的扩展名
        //************************************************************************
        bool fileOK = false;
        string uploadPath = string.Empty;//上传文件的路径
        string uploadInfo = UploadTB.Text;//文件说明
        //获取根文件绝对路径 
        string path = Server.MapPath("~/UserRes/" + "1" + "//");
        //如上传了文件，就判断文件格式 
        FileUpload FU = FileUpload1;
        if (FileUpload1.HasFile)
        {
            string fileExtension = System.IO.Path.GetExtension(FU.FileName).ToLower();
            string[] allowedExtensions ={ ".gif", ".jpg", ".png", ".bmp", ".zip", ".rar", ".doc", ".xls", ".docx", ".swf", };
            for (int i = 0; i < allowedExtensions.Length; i++)
            {
                if (fileExtension == allowedExtensions[i])
                {
                    fileOK = true;
                }
            }
        }
        //判断文件是否过大
        if (FileUpload1.PostedFile.ContentLength > 5242880) //获取上载文件的字节大小
        {
            Response.Write("<script>alert('对不起,文件太大,不能上传。上传文件不能大于5M ！')</script>");
            return;
        }
        uploadPath = System.DateTime.Now.ToString("yyyyMMddhhmmss") + oldName;
        //调用saveas方法，实现上传文件 
        if (fileOK)
        {
            try
            {
                FileUpload1.SaveAs(path + System.DateTime.Now.ToString("yyyyMMddhhmmss") + oldName);
                Response.Write("<script>alert('上传成功！')</script>");
                UploadTB.Text = string.Empty;
            }
            catch(Exception error)
            {
                Response.Write("<script>alert('''+error.ToString()+''')</script>");
            }
        }
        else
        { 
            Response.Write("<script>alert('上传失败，格式不允许！')</script>");
            UploadTB.Text = string.Empty;
            return;
        }
    }