CheckBoxList.Render(HtmlTextWriter) Methode

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Zeigt den CheckBoxList Client an.

protected:
 override void Render(System::Web::UI::HtmlTextWriter ^ writer);
protected public:
 override void Render(System::Web::UI::HtmlTextWriter ^ writer);
protected override void Render(System.Web.UI.HtmlTextWriter writer);
protected internal override void Render(System.Web.UI.HtmlTextWriter writer);
override this.Render : System.Web.UI.HtmlTextWriter -> unit
Protected Overrides Sub Render (writer As HtmlTextWriter)
Protected Friend Overrides Sub Render (writer As HtmlTextWriter)

Parameter

writer
HtmlTextWriter

A HtmlTextWriter that contains the output stream for rendering on the client.

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie die Render Methode in einem benutzerdefinierten Serversteuerelement überschreibt, sodass das CheckBoxList Bild immer angezeigt wird.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <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>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <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>

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);
        }
    }
}

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

Hinweise

Die Render Methode wird hauptsächlich von Steuerelemententwicklern in benutzerdefinierten Steuerelementen verwendet, die von der CheckBoxList Klasse abgeleitet sind.

Die Render Implementierung für ein CheckBoxList Steuerelement initialisiert ein RepeatInfo Objekt für die Liste und ruft die RenderRepeater Methode auf, die wiederum die RenderItem Methode zum Rendern einzelner Kontrollkästchenlistenelemente verwendet.

Gilt für:

Weitere Informationen