Substitution 构造函数
定义
重要
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初始化 Substitution 类的新实例。
public:
Substitution();public Substitution ();Public Sub New ()示例
下面的代码示例演示如何以编程方式将控件添加到 Substitution 输出缓存网页。 加载页面时，当前日期和时间将在标签中向用户显示。 页面的此部分仅每 60 秒缓存并更新一次。 控件 Substitution 执行时，它会调用 GetCurrentDateTime 方法。 返回的 GetCurrentDateTime 字符串将向用户显示。 页面的这一部分不会缓存，每次刷新页面时都会更新。
<%@ outputcache duration="60" varybyparam="none" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server" language="C#">
void Page_Load(object sender, System.EventArgs e)
{
// Programmatically create a Substitution control.
Substitution Substitution1 = new Substitution();
// Specify the callback method.
Substitution1.MethodName = "GetCurrentDateTime";
// Add the Substitution control to the controls
// collection of PlaceHolder1.
PlaceHolder1.Controls.Add (Substitution1);
// Display the current date and time in the label.
// Output caching applies to this section of the page.
CachedDateLabel.Text = DateTime.Now.ToString();
}
// The Substitution control calls this method to retrieve
// the current date and time. This section of the page
// is exempt from output caching.
public static string GetCurrentDateTime (HttpContext context)
{
return DateTime.Now.ToString ();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Substitution Class Example</title>
</head>
<body>
<form id="Form1" runat="server">
<h3>Substitution Constructor Example</h3>
<p>This section of the page is not cached:</p>
<asp:placeholder id="PlaceHolder1"
runat="Server">
</asp:placeholder>
<br />
<p>This section of the page is cached:</p>
<asp:label id="CachedDateLabel"
runat="Server">
</asp:label>
<br /><br />
<asp:button id="RefreshButton"
text="Refresh Page"
runat="Server">
</asp:button>
</form>
</body>
</html>
<%@ outputcache duration="60" varybyparam="none" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server" language="VB">
Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
' Programmatically create a Substitution control.
Dim Substitution1 As New Substitution
' Specify the callback method.
Substitution1.MethodName = "GetCurrentDateTime"
' Add the Substitution control to the controls
' collection of PlaceHolder1.
PlaceHolder1.Controls.Add(Substitution1)
' Display the current date and time in the label.
' Output caching applies to this section of the page.
CachedDateLabel.Text = DateTime.Now.ToString()
End Sub
' The Substitution control calls this method to retrieve
' the current date and time. This section of the page
' is exempt from output caching.
Shared Function GetCurrentDateTime(ByVal context As HttpContext) As String
Return DateTime.Now.ToString()
End Function
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Substitution Constructor Example</title>
</head>
<body>
<form id="Form1" runat="server">
<h3>Substitution Constructor Example</h3>
<p>This section of the page is not cached:</p>
<asp:placeholder id="PlaceHolder1"
runat="Server">
</asp:placeholder>
<br />
<p>This section of the page is cached:</p>
<asp:label id="CachedDateLabel"
runat="Server">
</asp:label>
<br /><br />
<asp:button id="RefreshButton"
text="Refresh Page"
runat="Server">
</asp:button>
</form>
</body>
</html>
注解
Substitution使用 构造函数创建和初始化 类的新实例Substitution。
