CheckBoxList.Render-Methode
Zeigt die CheckBoxList auf dem Client an.
Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)
Syntax
'Declaration
Protected Friend Overrides Sub Render ( _
writer As HtmlTextWriter _
)
'Usage
Dim writer As HtmlTextWriter
Me.Render(writer)
protected internal override void Render (
HtmlTextWriter writer
)
protected public:
virtual void Render (
HtmlTextWriter^ writer
) override
protected void Render (
HtmlTextWriter writer
)
protected internal override function Render (
writer : HtmlTextWriter
)
Parameter
- writer
Ein System.Web.UI.HtmlTextWriter, der den Ausgabestream für die Wiedergabe auf dem Client enthält.
Hinweise
Die Render-Methode wird primär von Steuerelemententwicklern beim Ableiten eines benutzerdefinierten Steuerelements von der CheckBoxList-Klasse verwendet.
Die Render-Implementierung für ein CheckBoxList-Steuerelement initialisiert ein RepeatInfo-Objekt für die Liste. Sie ruft die RenderRepeater-Methode auf, die wiederum mithilfe der RenderItem-Methode einzelne Elemente der Kontrollkästchenliste wiedergibt.
Beispiel
Das folgende Codebeispiel veranschaulicht das Überschreiben der Render-Methode in einem benutzerdefinierten Serversteuerelement, sodass die CheckBoxList immer ein Bild anzeigt.
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page language="VB" %>
<HTML>
<HEAD>
<title>Custom CheckBoxList - Render - VB.NET Example</title>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom CheckBoxList - Render - VB.NET Example</h3>
<aspSample:CustomCheckBoxListRender id="CheckBoxList" runat="server"
RepeatLayout="Table" RepeatColumns="2" CellSpacing="3" CellPadding="3">
<asp:ListItem Selected="True">Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
<asp:ListItem>Item 3</asp:ListItem>
<asp:ListItem>Item 4</asp:ListItem>
<asp:ListItem>Item 5</asp:ListItem>
<asp:ListItem>Item 6</asp:ListItem>
</aspSample:CustomCheckBoxListRender>
</form>
</body>
</HTML>
...
Imports System.Web
Imports System.Security.Permissions
Namespace Samples.AspNet.VB.Controls
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomCheckBoxListRender
Inherits System.Web.UI.WebControls.CheckBoxList
Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)
' Create and render a new Image Web control.
Dim image As New System.Web.UI.WebControls.Image
image.ID = "Image1"
image.ImageUrl = "image.jpg"
image.AlternateText = "Image for CheckBoxList1."
image.RenderControl(writer)
' Call the base class's Render method.
MyBase.Render(writer)
End Sub
End Class
End Namespace
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<HTML>
<HEAD>
<title>Custom CheckBoxList - Render - C# Example</title>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom CheckBoxList - Render - C# Example</h3>
<aspSample:CustomCheckBoxListRender
id="CheckBoxList1" runat="server">
<asp:ListItem Selected="True">Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
<asp:ListItem>Item 3</asp:ListItem>
<asp:ListItem>Item 4</asp:ListItem>
<asp:ListItem>Item 5</asp:ListItem>
<asp:ListItem>Item 6</asp:ListItem>
</aspSample:CustomCheckBoxListRender>
</form>
</body>
</HTML>
...
using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class CustomCheckBoxListRender : System.Web.UI.WebControls.CheckBoxList
{
protected override void Render(System.Web.UI.HtmlTextWriter writer)
{
// Create and render a new Image Web control.
System.Web.UI.WebControls.Image image = new System.Web.UI.WebControls.Image();
image.ID = "Image1";
image.ImageUrl = "image.jpg";
image.AlternateText = "Image for CheckBoxList1.";
image.RenderControl(writer);
// Call the base class's Render method.
base.Render(writer);
}
}
}
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page language="VJ#" %>
<HTML>
<HEAD>
<title>Custom CheckBoxList - Render - VJ# Example</title>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom CheckBoxList - Render - VJ# Example</h3>
<aspSample:CustomCheckBoxListRender
id="CheckBoxList1" runat="server">
<asp:ListItem Selected="True">Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
<asp:ListItem>Item 3</asp:ListItem>
<asp:ListItem>Item 4</asp:ListItem>
<asp:ListItem>Item 5</asp:ListItem>
<asp:ListItem>Item 6</asp:ListItem>
</aspSample:CustomCheckBoxListRender>
</form>
</body>
</HTML>
...
package Samples.AspNet.JSL.Controls;
public class CustomCheckBoxListRender
extends System.Web.UI.WebControls.CheckBoxList
{
protected void Render(System.Web.UI.HtmlTextWriter writer)
{
// Create and render a new Image Web control.
System.Web.UI.WebControls.Image image =
new System.Web.UI.WebControls.Image();
image.set_ID("Image1");
image.set_ImageUrl("image.jpg");
image.set_AlternateText("Image for CheckBoxList1.");
image.RenderControl(writer);
// Call the base class's Render method.
super.Render(writer);
} //Render
} //CustomCheckBoxListRender
Plattformen
Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
Siehe auch
Referenz
CheckBoxList-Klasse
CheckBoxList-Member
System.Web.UI.WebControls-Namespace