http://www.asp.net/AJAX/Documentation/Live/tutorials/UsingUpdatePanelControls.aspx
管理掌握触发器/以编程方式刷新一个UpdatePanel
触发一个UpdatePanel控件使UpdatePanel控件开始刷新的控件,要通过ScriptManager在Page页上"注册".这,通常会自动发生,当子控件在UpdatePanel控件的ContentTemplate内的时候。你也可以明确地指定触发器---通过使用UpdatePanel控件的Triggers集合UpdatePanel1.Triggers是UpdatePanel1不是UpdatePanel!另外,你也可以在你的页面的服务器端代码(cs代码内)编程(动词)指定触发器以引起UpdatePanel控件的刷新动作.万一触发器控件在"设计时"不可用,你也可以注册(动词)控件成为(动词)一个触发器---通过使用ScriptManager控件的RegisterAsyncPostBackControl(Control)方法,当然使用时是ScriptManager1而不是ScriptManager!
被以编程方式指定为触发器的控件必须被注册----在任何一次当PostBack发生的时候。我们要求你把调用UpdatePanel控件的RegisterAsyncPostBackControl(Control)方法的代码放在你的页面的Page_Load事件里，象下面这样：
protected void Page_Load()
{
ScriptManager1.RegisterAsyncPostBackControl(SurveyDataList);
}要以编程方式"刷新"UpdatePanel控件,你可以主动调用UpdatePanel控件的Update()方法.这是很有用的,尤其是在必须在服务器端执行一些处理-----在刷新UpdatePanel控件之前.代码:
protected void ChoicesRadioButtonList_SelectedIndexChanged(object sender, EventArgs e){ SortedList answers = this.AnsweredQuestions; RadioButtonList r = (RadioButtonList)sender; answers[r.ToolTip] = r.SelectedValue; this.AnsweredQuestions = answers; ResultsList.DataSource = this.AnsweredQuestions; ResultsList.DataBind(); if (this.AnsweredQuestions.Count == SurveyDataList.Items.Count) SubmitButton.Visible = true; UpdatePanel1.Update();}下面的例子展示了一个页面,该页面注册了一个控件作为触发器----通过使用RegisterAsyncPostBackControl(Control)方法，并且以编程方式刷新一个UpdatePanel控件-----通过使用Update()方法。
<%@ Page Language="C#" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><script runat="server"> protected SortedList AnsweredQuestions
{
get { return (SortedList)(ViewState["AnsweredQuestions"] ?? new SortedList()); } set { ViewState["AnsweredQuestions"] = value; }
} protected void Page_Load() { ScriptManager1.RegisterAsyncPostBackControl(SurveyDataList); } protected void ChoicesRadioButtonList_SelectedIndexChanged(object sender, EventArgs e) { SortedList answers = this.AnsweredQuestions; RadioButtonList r = (RadioButtonList)sender; answers[r.ToolTip] = r.SelectedValue; this.AnsweredQuestions = answers; ResultsList.DataSource = this.AnsweredQuestions; ResultsList.DataBind(); if (this.AnsweredQuestions.Count == SurveyDataList.Items.Count) SubmitButton.Visible = true; UpdatePanel1.Update(); } protected void SubmitButton_Click(object sender, EventArgs e) { // Submit responses. }</script><html xmlns="http://www.w3.org/1999/xhtml"><head id="Head1" runat="server"> <title>Registering Controls as Async Postback Controls</title> <style type="text/css"> .AnswerFloatPanelStyle { background-color: bisque; position: absolute; right: 10px; height: 130px; width: 150px; border-right: silver thin solid; border-top: silver thin solid; border-left: silver thin solid; border-bottom: silver thin solid; } </style></head><body> <form id="form1" runat="server"> <div> <asp:ScriptManager ID="ScriptManager1" runat="server" /> <div id="AnswerFloatPanel" class="AnswerFloatPanelStyle" runat="server"> <asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server"> <ContentTemplate> Completed Questions: <asp:DataList ID="ResultsList" runat="server"> <ItemTemplate> <asp:Label ID="ResultQuestion" runat="server" Text='<%# Eval("Key") %>' /> :: <asp:Label ID="ResultAnswer" runat="server" Text='<%# Eval("Value") %>' /> </ItemTemplate> </asp:DataList> <p style="text-align: right"> <asp:Button ID="SubmitButton" Text="Submit" runat="server" Visible="false" OnClick="SubmitButton_Click" /> </p> <asp:Label ID="Message" runat="Server" /> </ContentTemplate> </asp:UpdatePanel> </div> <asp:XmlDataSource ID="SurveyDataSource" runat="server" XPath="/Questions/Question" DataFile="~/App_Data/SurveyQuestions.xml"/> <asp:DataList ID="SurveyDataList" DataSourceID="SurveyDataSource" runat="server"> <ItemTemplate> <table cellpadding="2" cellspacing="2"> <tr> <td valign="top"> <asp:Label id="QuestionLabel" Text='<%# XPath("@Title")%>' runat="server" /> </td> </tr> <tr><td> <asp:RadioButtonList ID="ChoicesRadioButtonList" runat="server" DataSource='<%#XPathSelect("Choices/Choice") %>' DataTextField="InnerText" DataValueField="InnerText" AutoPostBack="True" ToolTip='<%# "Question" + XPath("@ID") %>' OnSelectedIndexChanged="ChoicesRadioButtonList_SelectedIndexChanged"/> </td></tr> </table> <hr /> </ItemTemplate> </asp:DataList> </div> </form></body></html>