input button 的 onserverclick 事件

aspx:

 <input id="Button1" runat="server" class="btn2"  onserverclick="Button1_ServerClick"
                                    type="button" value="关闭" />

aspx.cs:

  protected void Button1_ServerClick(object sender, EventArgs e)
    {
       
        if (this.Hidden1.Value.Length > 0)
        {
            Response.Write("<Script>returnValue='ok';window.close();</Script>");
        }
        else
        {
            Response.Write("<Script>window.close();</Script>");
        }
        
    }