HtmlInputHidden.OnPreRender-Methode

Artikel
08/20/2007

Löst das Control.PreRender-Ereignis aus.

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 wird kurz vor dem Rendern des HtmlInputHidden-Steuerelements aufgerufen. Die OnPreRender-Methode wird hauptsächlich von Entwicklern von Steuerelementen zum Erweitern der Funktionalität des HtmlInputHidden-Steuerelements verwendet.

Beispiel

Im folgenden Codebeispiel wird das Überschreiben der OnPreRender-Methode veranschaulicht, sodass diese die HTML-Codierung auf den Eingabewert in einem benutzerdefinierten HtmlInputHidden-Serversteuerelement anwendet.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<HTML>
    <HEAD>
    
    <title>Custom HtmlInputHidden - OnPreRender - Visual Basic Example</title>
    
    <script runat="server">
      Sub Page_Load(sender As Object, e As EventArgs)
        HtmlInputHidden1.Value = "<Hello HtmlInputHidden World>"
      End Sub
    </script>
    </HEAD>
    <body onload="alert('View the source to see the HTML Hidden Input value.')">
        <form id="Form1" name="Form1" method="post" runat="server">
            <h3>Custom HtmlInputHidden - OnPreRender - Visual Basic Example</h3>
        
          <aspSample:CustomHtmlInputHiddenOnPreRender 
            id="HtmlInputHidden1" 
            name="HtmlInputHidden1"
            runat="server" 
            type="hidden">
            
        </form>
    </body>
</HTML>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<HTML>
    <HEAD>
        <title>Custom HtmlInputHidden - OnPreRender - C# Example</title>
    <script runat="server">
      void Page_Load(Object sender, EventArgs e) 
      {
        HtmlInputHidden1.Value = "<Hello Html Input Hidden World.>";
      }
    </script>
    </HEAD>
    <body onload="alert('View the source to see the HTML Hidden Input value.')">
        <form id="Form1" name="Form1" method="post" runat="server">
            <h3>Custom HtmlInputHidden - OnPreRender - C# Example</h3>
        
          <aspSample:CustomHtmlInputHiddenOnPreRender 
            id="HtmlInputHidden1" 
            name="HtmlInputHidden1"
            runat="server" 
            type="hidden">
            
        </form>
    </body>
</HTML>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
    <HEAD>
        <title>Custom HtmlInputHidden - OnPreRender - VJ# Example</title>
    <script runat="server">
    void Page_Load(Object sender, EventArgs e) 
    {
        HtmlInputHidden1.set_Value("<Hello Html Input Hidden World.>");
    } //Page_Load
    </script>
    </HEAD>
    <body onload="alert('View the source to see the HTML Hidden Input value.')">
        <form id="Form1" name="Form1" method="post" runat="server">
            <h3>Custom HtmlInputHidden - OnPreRender - VJ# Example</h3>
        
          <aspSample:CustomHtmlInputHiddenOnPreRender 
            id="HtmlInputHidden1" 
            name="HtmlInputHidden1"
            runat="server" 
            type="hidden">
            
        </form>
    </body>
</HTML>

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

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

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

        ' Encode the Hidden Input value as HTML.
        Me.Value = System.Web.HttpContext.Current.Server.HtmlEncode(Me.Value)
    End Sub
End Class

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputHiddenOnPreRender : System.Web.UI.HtmlControls.HtmlInputHidden
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);
            
            // Encode the Hidden Input value as HTML.
            this.Value = System.Web.HttpContext.Current.Server.HtmlEncode(this.Value);
        }
    }
}

package Samples.AspNet.JSL.Controls;

public class CustomHtmlInputHiddenOnPreRender
    extends System.Web.UI.HtmlControls.HtmlInputHidden
{
    protected void OnPreRender(System.EventArgs e)
    {
        // Call the base's OnPreRender method.
        super.OnPreRender(e);
        // HtmlEncode the Hidden Input value.
        this.set_Value(System.Web.HttpContext.get_Current().get_Server().
            HtmlEncode(this.get_Value()));
    } //OnPreRender
} //CustomHtmlInputHiddenOnPreRender

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

HtmlInputHidden-Klasse
HtmlInputHidden-Member
System.Web.UI.HtmlControls-Namespace
OnPreRender

Weitere Ressourcen

HTML-Serversteuerelemente

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