在ASP.NET AJAX中动态添加控件到UpdatePanel

我有以下很简单的代码

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
    <asp:PlaceHolder ID="PlaceHolder1" runat="server">
    </asp:PlaceHolder>
    <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
</ContentTemplate>
</asp:UpdatePanel>

和代码

protected void Button1_Click(object sender,EventArgs e)
{
    Literal literal = new Literal();
    literal.Text = DateTime.Now.ToString();
    literal.ID = DateTime.Now.Ticks.ToString();

    // These both work fine the first time the button is clicked
    // but the second time nothing is added.
    UpdatePanel1.ContentTemplateContainer.Controls.Add(literal);
    PlaceHolder1.Controls.Add(literal);
}

我的问题出在于文字控制只有一次添加.我已经浏览了谷歌和博客网站(加上书籍),但没有任何运气.我失踪了什么

解决方法

这将在您每次单击按钮时创建一个额外的控件(虽然每次按下按钮时都会更新时间戳,因为重新创建控件)

protected void Button1_Click(object sender,EventArgs e)
{
    int count = 0;

    if (ViewState["ButtonCount"] != null)
    {
        count = (int)ViewState["ButtonCount"];
    }

    count++;
    ViewState["ButtonCount"] = count;

    for (int i = 0; i < count; i++)
    {
        Literal literal = new Literal();
        literal.Text = DateTime.Now.ToString();
        literal.ID = DateTime.Now.Ticks.ToString();

        UpdatePanel1.ContentTemplateContainer.Controls.Add(literal);
        PlaceHolder1.Controls.Add(literal);
    }            
}

（编辑：安卓应用网）

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