動态建立伺服器端控件

protected void Page_Load(object sender, EventArgs e)
    {
        if (this.IsPostBack)
        {
            CreateFileUpLoadControls();
        }
    }

    protected void ImageButton2_Click(object sender, ImageClickEventArgs e)
    {
        //回傳調用Page_Load
    }

    private void CreateFileUpLoadControls()
    {
        if (ViewState["controlNum"] == null) ViewState["controlNum"] = 1;
        FileUpload fu;
        HtmlGenericControl div;
        for (int i = 0; i < Convert.ToInt32(ViewState["controlNum"]); i++)
        {
            div = new HtmlGenericControl();
            div.ID = "div" + i.ToString();
            div.TagName = "div";
            div.Attributes["class"] = "fuDiv";
            
            fu = new FileUpload();
            fu.ID = "fu" + i.ToString();

            div.Controls.Add(fu);
            fuControls.Controls.Add(div);
        }
        ViewState["controlNum"] = Convert.ToInt32(ViewState["controlNum"]) + 1;
    }