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Sys.WebForms.InitializeRequestEventArgs 类

  • 项目

更新：2007 年 11 月

由 Sys.WebForms.PageRequestManager 类的 initializeRequest 事件用来将参数信息传递给事件处理程序。

命名空间：Sys.WebForms

继承：Sys.CancelEventArgs

new Sys.WebForms.InitializeRequestEventArgs();

构造函数

名称

说明

Sys.WebForms.InitializeRequestEventArgs 构造函数

初始化 InitializeRequestEventArgs 类的新实例。

成员

名称

说明

Sys.WebForms.InitializeRequestEventArgs postBackElement 属性

获取启动异步回发的回发元素。

Sys.WebForms.InitializeRequestEventArgs request 属性

获取表示当前回发的请求对象。
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 request 属性访问请求对象，使用 postBackElement 属性确定导致回发的元素。

PageRequestManager 类的 initializeRequest 事件在开始处理异步请求之前引发。

示例

下面的示例演示如何使用 initializeRequest 事件以允许取消异步回发。initializeRequest 事件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。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 PageRequestManager 类的 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> &nbsp;&nbsp;&nbsp;&nbsp;
                        <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> &nbsp;&nbsp;&nbsp;&nbsp;
                        <asp:LinkButton ID="CancelRefresh" runat="server">cancel</asp:LinkButton>
                        </div>                        
                    </asp:Panel>
                </ContentTemplate>
            </asp:UpdatePanel>
            </div>
        </div>
    </form>
</body>
</html>

请参见

参考

Sys.CancelEventArgs 类