TextBox.Render(HtmlTextWriter) 方法
定義
重要
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將 TextBox 控制項渲染到指定的 HtmlTextWriter 物件。
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 -> unitProtected Overrides Sub Render (writer As HtmlTextWriter)Protected Friend Overrides Sub Render (writer As HtmlTextWriter)參數
- writer
- HtmlTextWriter
那 HtmlTextWriter 個接收渲染輸出的。
範例
以下程式碼範例示範如何在自訂伺服器控制項中覆寫該 Render 方法，使 TextBox 控制項始終以影像顯示。
這很重要
此範例中有一個文字框可接受使用者輸入，這可能構成安全威脅。 預設情況下，ASP.NET 網頁會驗證使用者輸入中不包含腳本或 HTML 元素。 欲了解更多資訊，請參閱 腳本漏洞概述。
<%@ 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 - Render - C# Example</title>
</head>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom TextBox - Render - C# Example</h3>
<aspSample:CustomTextBoxRender
id="TextBox1"
runat="server">Hello World!
</aspSample:CustomTextBoxRender>
</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 - Render - VB.NET Example</title>
</head>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom TextBox - Render - VB.NET Example</h3>
<aspSample:CustomTextBoxRender id="TextBox1"
runat="server">Hello World!</aspSample:CustomTextBoxRender>
</form>
</body>
</html>
using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
[AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
public sealed class CustomTextBoxRender : System.Web.UI.WebControls.TextBox
{
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 TextBox1.";
image.RenderControl(writer);
// Create a BR tag.
writer.RenderBeginTag(System.Web.UI.HtmlTextWriterTag.Br);
// 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 CustomTextBoxRender
Inherits System.Web.UI.WebControls.TextBox
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 TextBox1."
image.RenderControl(writer)
' Create a BR tag.
writer.RenderBeginTag(System.Web.UI.HtmlTextWriterTag.Br)
' Call the base class's Render method.
MyBase.Render(writer)
End Sub
End Class
End Namespace
備註
此 Render 方法會將控制項的 TextBox 開始標籤和結束標籤渲染到 HtmlTextWriter 物件上，讓它輸出到用戶端。 若屬性 TextMode 設定為 MultiLine，控制項內容 TextBox 會以 HTML <textarea> 元素呈現。
此 Render 方法主要由控制開發者使用，以擴充控制功能 TextBox 。
