共用方式為

TextBox.OnPreRender(EventArgs) 方法

  • 參考

定義

命名空間:
System.Web.UI.WebControls
組件:
System.Web.dll

如果 AutoPostBack 為 true，則在用戶端上呈現前，會先註冊產生回傳事件的用戶端指令碼。

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)

參數

e
EventArgs

包含事件資料的 EventArgs。

範例

下列程式代碼範例示範如何覆寫 OnPreRender 方法，使其一律會在自定義 TextBox 伺服器控件中顯示一點框線。

重要

這個範例有一個可接受使用者輸入的文字方塊，這可能會造成安全性威脅。 根據預設，ASP.NET Web 網頁會驗證使用者輸入未包含指令碼或 HTML 項目。 如需詳細資訊，請參閱 Script Exploits Overview (指令碼攻擊概觀)。

<%@ 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 TextBox - OnPreRender - C# Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom TextBox - OnPreRender - C# Example</h3>
            
            <aspSample:CustomTextBoxOnPreRender 
              id="TextBox1" 
              runat="server">Hello World!
            </aspSample:CustomTextBoxOnPreRender>
            
        </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 TextBox - OnPreRender - VB.NET Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom TextBox - OnPreRender - VB.NET Example</h3>
            
            <aspSample:CustomTextBoxOnPreRender id="TextBox1" 
             runat="server">Hello World!</aspSample:CustomTextBoxOnPreRender>
        </form>
    </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
  [AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
  public sealed class CustomTextBoxOnPreRender : System.Web.UI.WebControls.TextBox
  {
    protected override void OnPreRender(System.EventArgs e)
    {
      // Run the OnPreRender method on the base class.
      base.OnPreRender(e);

      // Display the TextBox with a 1 point border.
      this.BorderWidth = System.Web.UI.WebControls.Unit.Point(1);
    }
  }
}

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomTextBoxOnPreRender
        Inherits System.Web.UI.WebControls.TextBox

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

            ' Run the OnPreRender method on the base class.
            MyBase.OnPreRender(e)

            ' Display the TextBox with a 1 point border.
            Me.BorderWidth = System.Web.UI.WebControls.Unit.Point(1)
        End Sub
    End Class
End Namespace

適用於