通过

HtmlInputHidden.OnPreRender(EventArgs) 方法

  • 参考

定义

命名空间:
System.Web.UI.HtmlControls
程序集:
System.Web.dll

引发 PreRender 事件。

protected:
 override void OnPreRender(EventArgs ^ e);
protected public:
 override void OnPreRender(EventArgs ^ e);
protected override void OnPreRender (EventArgs e);
protected internal override void OnPreRender (EventArgs e);
override this.OnPreRender : EventArgs -> unit
Protected Overrides Sub OnPreRender (e As EventArgs)
Protected Friend Overrides Sub OnPreRender (e As EventArgs)

参数

e
EventArgs

包含事件数据的 EventArgs。

示例

下面的代码示例演示如何重写 方法， OnPreRender 以便它将 HTML 编码应用于自定义 HtmlInputHidden 服务器控件中的输入值。

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!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 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" 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.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<!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 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" method="post" runat="server">
            <h3>Custom HtmlInputHidden - OnPreRender - Visual Basic Example</h3>
        
          <aspSample:CustomHtmlInputHiddenOnPreRender 
            id="HtmlInputHidden1" 
            runat="server" 
            type="hidden">
            
        </form>
    </body>
</html>

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);
        }
    }
}

<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

注解

在 OnPreRender 呈现 HtmlInputHidden 控件之前调用 方法。 方法 OnPreRender 主要由扩展控件功能的 HtmlInputHidden 控件开发人员使用。

适用于

另请参阅