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HtmlInputCheckBox.OnPreRender-Methode

  • Artikel

Löst das OnPreRender-Ereignis aus und registriert das -Steuerelement als ein Steuerelement, für das eine Postbackbehandlung erforderlich ist.

Namespace: System.Web.UI.HtmlControls
Assembly: System.Web (in system.web.dll)

Syntax

'Declaration
Protected Friend Overrides Sub OnPreRender ( _
    e As EventArgs _
)
'Usage
Dim e As EventArgs

Me.OnPreRender(e)

protected internal override void OnPreRender (
    EventArgs e
)

protected public:
virtual void OnPreRender (
    EventArgs^ e
) override

protected void OnPreRender (
    EventArgs e
)

protected internal override function OnPreRender (
    e : EventArgs
)

Parameter

  • e
    Ein EventArgs, das Ereignisdaten enthält.

Hinweise

Die OnPreRender-Methode überschreibt die OnPreRender-Basismethode. OnPreRender wird hauptsächlich von Steuerelemententwicklern verwendet.

Beispiel

Im folgenden Codebeispiel wird das Überschreiben der OnPreRender-Methode in einem benutzerdefinierten Serversteuerelement veranschaulicht, sodass in jedem HtmlInputCheckBox-Steuerelement ein Title-Attribut hinzugefügt wird.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<HTML>
  <HEAD>
    <title>Custom HtmlInputCheckBox - OnPreRender - Visual Basic Example</title>
    <script runat=server>
      Sub Button1_Click(sender As Object, e As EventArgs)
        Div1.InnerHtml = ""

        If HtmlInputCheckBox1.Checked = True Then
            Div1.InnerHtml = "You like basketball. "
        End If

        If HtmlInputCheckBox2.Checked = True Then
            Div1.InnerHtml += "You like football. "
        End If

        If HtmlInputCheckBox3.Checked = True Then
            Div1.InnerHtml += "You like soccer. "
        End If
      End Sub

    </script>
  </HEAD>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - Visual Basic Example</h3>
      <P>
      Enter Interests:<br>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </P>
      <P>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        OnServerClick="Button1_Click"
        name="Button1">
      </P>

      <P>
      <DIV id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
        ms_positioning="FlowLayout" />
      </P>
    </form>
  </body>
</HTML>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<HTML>
  <HEAD>
    <title>Custom HtmlInputCheckBox - OnPreRender - C# Example</title>
    <script runat=server>
      void Button1_Click(Object sender, EventArgs e)
      {
        Div1.InnerHtml = "";

        if(HtmlInputCheckBox1.Checked == true)
        {
          Div1.InnerHtml = "You like basketball. ";
        }

        if(HtmlInputCheckBox2.Checked == true)
        {
          Div1.InnerHtml += "You like football. ";
        }

        if(HtmlInputCheckBox3.Checked == true)
        {
          Div1.InnerHtml += "You like soccer. ";
        }
      }
    </script>
  </HEAD>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - C# Example</h3>
      <P>
      Enter Interests:<br>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </P>
      <P>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        OnServerClick="Button1_Click"
        name="Button1">
      </P>

      <P>
      <DIV id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
        ms_positioning="FlowLayout" />
      </P>
    </form>
  </body>
</HTML>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
  <HEAD>
    <title>Custom HtmlInputCheckBox - OnPreRender - C# Example</title>
    <script runat=server>
    void Button1_Click(Object sender, EventArgs e)
    {
        Div1.set_InnerHtml("");
        if(HtmlInputCheckBox1.get_Checked() == true) {
            Div1.set_InnerHtml("You like basketball. ");
        }
        if(HtmlInputCheckBox2.get_Checked() == true) {
            Div1.set_InnerHtml(Div1.get_InnerHtml() + "You like football. ");
        }
        if(HtmlInputCheckBox3.get_Checked() == true) {
            Div1.set_InnerHtml(Div1.get_InnerHtml() + "You like soccer. ");
        }
    } //Button1_Click
    </script>
  </HEAD>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - VJ# Example</h3>
      <P>
      Enter Interests:<br>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </P>
      <P>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        OnServerClick="Button1_Click"
        name="Button1">
      </P>

      <P>
      <DIV id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
        ms_positioning="FlowLayout" />
      </P>
    </form>
  </body>
</HTML>

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls

    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomHtmlInputCheckBoxOnPreRender
        Inherits System.Web.UI.HtmlControls.HtmlInputCheckBox

        Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)

            ' Call the base class's OnPreRender method.
            MyBase.OnPreRender(e)

            ' Add a Title attribute to each HtmlInputCheckBox.
            Me.Attributes.Add("title", "If you like " + Me.Value + ", then select this check box.")
        End Sub
    End Class

End Namespace

using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputCheckBoxOnPreRender : System.Web.UI.HtmlControls.HtmlInputCheckBox
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);
            
            // Add a Title attribute to each HtmlInputCheckBox.
            this.Attributes.Add("title", "If you like " + this.Value + ", then select this check box.");
        }
    }
}

package Samples.AspNet.JSL.Controls;

public class CustomHtmlInputCheckBoxOnPreRender
    extends System.Web.UI.HtmlControls.HtmlInputCheckBox
{
    protected void OnPreRender(System.EventArgs e)
    {
        // Call the base class's OnPreRender method.
        super.OnPreRender(e);
        // Add a Title attribute to each HtmlInputCheckBox.
        this.get_Attributes().Add("title", "If you like " 
            + this.get_Value() + ", then select this check box.");
    } //OnPreRender
} //CustomHtmlInputCheckBoxOnPreRender

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

HtmlInputCheckBox-Klasse
HtmlInputCheckBox-Member
System.Web.UI.HtmlControls-Namespace

Weitere Ressourcen

HTML-Serversteuerelemente