更新：2007 年 11 月
为可以取消的事件提供基类。
命名空间：Sys
var args = new Sys.CancelEventArgs();
构造函数
名称 |
说明 |
|---|---|
初始化 CancelEventArgs 类的新实例。 |
成员
名称 |
说明 |
|---|---|
获取或设置一个值，该值指定事件源是否应取消导致事件的操作。 |
.gif "说明") 说明： |
|---|
此类包含支持客户端-脚本基础结构的私有成员，不能在代码中直接使用。私有成员的名称必须以下划线开头 ( _ )。 |
备注
事件处理程序可以使用 cancel 属性取消正在进行的操作。取消事件的语义取决于事件源。
示例
下面的示例演示如何使用 InitializeRequestEventArgs 类的 cancel 属性，该属性派生自 CancelEventArgs 类。在此示例中，initializeRequest 事件的处理程序实现取消异步回发。处理程序中的脚本使用 PageRequestManager 类的 isInAsyncPostBack 属性确定异步回发是否正在进行中。如果回发正在进行中，则使用 postBackElement 属性确定导致回发的元素的 ID。如果该 ID 与取消回发的按钮的 ID 相匹配，则调用 abortPostBack 方法。否则，使用 CancelEventArgs 类的 cancel 属性取消当前请求。
<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Protected Sub ButtonClick_Handler(ByVal sender As Object, ByVal e As System.EventArgs)
System.Threading.Thread.Sleep(3000)
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>PageRequestManager initializeRequest Example</title>
<style type="text/css">
body {
font-family: Tahoma;
}
a {
text-decoration: none;
}
a:hover {
text-decoration: underline;
}
div.UpdatePanelStyle{
width: 300px;
height: 300px;
}
div.AlertStyle {
font-size: smaller;
background-color: #FFC080;
height: 20px;
visibility: hidden;
}
div.Container {
display: inline;
float: left;
width: 330px;
height: 300px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<script type="text/javascript" language="javascript">
var divElem = 'AlertDiv';
var messageElem = 'AlertMessage';
Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(CheckStatus);
function CheckStatus(sender, args)
{
var prm = Sys.WebForms.PageRequestManager.getInstance();
if (prm.get_isInAsyncPostBack() & args.get_postBackElement().id == 'CancelRefresh') {
prm.abortPostBack();
}
else if (prm.get_isInAsyncPostBack() & args.get_postBackElement().id == 'RefreshButton') {
args.set_cancel(true);
ActivateAlertDiv('visible', 'Still working on previous request.');
}
else if (!prm.get_isInAsyncPostBack() & args.get_postBackElement().id == 'RefreshButton') {
ActivateAlertDiv('visible', 'Processing....');
}
}
function ActivateAlertDiv(visString, msg)
{
var adiv = $get(divElem);
var aspan = $get(messageElem);
adiv.style.visibility = visString;
aspan.innerHTML = msg;
}
</script>
<div class="Container" >
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="Server" >
<ContentTemplate>
<asp:Panel ID="Panel1" runat="server" GroupingText="UpdatePanel"
CssClass="UpdatePanelStyle">
Last update:
<%=DateTime.Now.ToString() %>.
<asp:Button runat="server" ID="RefreshButton" Text="Refresh"
OnClick="ButtonClick_Handler" />
<div id="AlertDiv" class="AlertStyle">
<span id="AlertMessage"></span>
<asp:LinkButton ID="CancelRefresh" runat="server">cancel</asp:LinkButton>
</div>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</div>
</form>
</body>
</html>
<%@ 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 void ButtonClick_Handler(object sender, EventArgs e)
{
System.Threading.Thread.Sleep(3000);
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>PageRequestManager initializeRequest Example</title>
<style type="text/css">
body {
font-family: Tahoma;
}
a {
text-decoration: none;
}
a:hover {
text-decoration: underline;
}
div.UpdatePanelStyle{
width: 300px;
height: 300px;
}
div.AlertStyle {
font-size: smaller;
background-color: #FFC080;
height: 20px;
visibility: hidden;
}
div.Container {
display: inline;
float: left;
width: 330px;
height: 300px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<script type="text/javascript" language="javascript">
var divElem = 'AlertDiv';
var messageElem = 'AlertMessage';
Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(CheckStatus);
function CheckStatus(sender, args)
{
var prm = Sys.WebForms.PageRequestManager.getInstance();
if (prm.get_isInAsyncPostBack() & args.get_postBackElement().id == 'CancelRefresh') {
prm.abortPostBack();
}
else if (prm.get_isInAsyncPostBack() & args.get_postBackElement().id == 'RefreshButton') {
args.set_cancel(true);
ActivateAlertDiv('visible', 'Still working on previous request.');
}
else if (!prm.get_isInAsyncPostBack() & args.get_postBackElement().id == 'RefreshButton') {
ActivateAlertDiv('visible', 'Processing....');
}
}
function ActivateAlertDiv(visString, msg)
{
var adiv = $get(divElem);
var aspan = $get(messageElem);
adiv.style.visibility = visString;
aspan.innerHTML = msg;
}
</script>
<div class="Container" >
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="Server" >
<ContentTemplate>
<asp:Panel ID="Panel1" runat="server" GroupingText="UpdatePanel"
CssClass="UpdatePanelStyle">
Last update:
<%=DateTime.Now.ToString() %>.
<asp:Button runat="server" ID="RefreshButton" Text="Refresh"
OnClick="ButtonClick_Handler" />
<div id="AlertDiv" class="AlertStyle">
<span id="AlertMessage"></span>
<asp:LinkButton ID="CancelRefresh" runat="server">cancel</asp:LinkButton>
</div>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</div>
</form>
</body>
</html>