动态更改Flajaxian上传文件夹名称

<fjx:FileUploader ID="FileUploader1" runat="server">
<Adapters>
    <fjx:DirectAmazonUploader OnFileNameDetermining="FileUploader1_FileNameDetermining"
        AccessKey="WebConfig:AmazonAccessKey"
        SecretKey="WebConfig:AmazonSecretKey"
        BucketName="media.sitename.com" />
</Adapters>
</fjx:FileUploader>

    protected void Page_Load(object sender, EventArgs e)
    {

          ((com.flajaxian.DirectAmazonUploader)FileUploader1.Adapters[0]).Path = Request.Params["sid"].ToString();

    }

    protected void FileUploader1_FileNameDetermining(object sender, com.flajaxian.FileNameDeterminingEventArgs e)
    {
        Random r = new Random();
        e.FileName = r.Next(10000) + ".jpg";

    }