TextBox.Render(HtmlTextWriter) 方法
定义
重要
一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。 对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。
将 TextBox 控件呈现给指定的 HtmlTextWriter 对象。
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)参数
- writer
- HtmlTextWriter
接收呈现输出的 HtmlTextWriter。
示例
下面的代码示例演示如何重写 Render 自定义服务器控件中的方法， TextBox 以便始终显示带有图像的控件。
重要
此示例具有一个接受用户输入的文本框，这是一个潜在的安全威胁。 默认情况下，ASP.NET 网页验证用户输入是否不包含脚本或 HTML 元素。 有关详细信息，请参阅脚本侵入概述。
<%@ 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
注解
该方法 Render 将控件的 TextBox 开始标记和结束标记呈现给 HtmlTextWriter 客户端输出的对象。 如果属性 TextMode 设置为 MultiLine，控件 TextBox 的内容将呈现为 HTML <textarea> 元素。
该方法 Render 主要用于控件开发人员扩展控件的功能 TextBox 。