CheckBoxList.Render(HtmlTextWriter) 方法

  • 参考

定义

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

在客户端上显示 CheckBoxList。

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 -> unit
Protected Overrides Sub Render (writer As HtmlTextWriter)
Protected Friend Overrides Sub Render (writer As HtmlTextWriter)

参数

writer
HtmlTextWriter

包含用于在客户端上进行呈现的输出流的 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，以便 CheckBoxList 始终显示图像。

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<!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 CheckBoxList - Render - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom CheckBoxList - Render - C# Example</h3>

      <aspSample:CustomCheckBoxListRender
        id="CheckBoxList1" runat="server">
        <asp:ListItem Selected="True">Item 1</asp:ListItem>
        <asp:ListItem>Item 2</asp:ListItem>
        <asp:ListItem>Item 3</asp:ListItem>
        <asp:ListItem>Item 4</asp:ListItem>
        <asp:ListItem>Item 5</asp:ListItem>
        <asp:ListItem>Item 6</asp:ListItem>
      </aspSample:CustomCheckBoxListRender>

    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page language="VB" %>
<!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 CheckBoxList - Render - VB.NET Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom CheckBoxList - Render - VB.NET Example</h3>
      <aspSample:CustomCheckBoxListRender id="CheckBoxList" runat="server"
       RepeatLayout="Table" RepeatColumns="2" CellSpacing="3" CellPadding="3">
                <asp:ListItem  Selected="True">Item 1</asp:ListItem>
                <asp:ListItem>Item 2</asp:ListItem>
                <asp:ListItem>Item 3</asp:ListItem>
                <asp:ListItem>Item 4</asp:ListItem>
                <asp:ListItem>Item 5</asp:ListItem>
                <asp:ListItem>Item 6</asp:ListItem>
            </aspSample:CustomCheckBoxListRender>
    </form>
  </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomCheckBoxListRender : System.Web.UI.WebControls.CheckBoxList
    {
        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 CheckBoxList1.";
        image.RenderControl(writer);

        // 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 CustomCheckBoxListRender
        Inherits System.Web.UI.WebControls.CheckBoxList

        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 CheckBoxList1."
            image.RenderControl(writer)

            ' Call the base class's Render method.
            MyBase.Render(writer)
        End Sub
    End Class
End Namespace

注解

方法 Render 主要由派生自 CheckBoxList 类的自定义控件中的控件开发人员使用。

Render控件的 CheckBoxList 实现初始化RepeatInfo列表的 对象，并调用 RenderRepeater 方法，该方法又使用 RenderItem 方法呈现单个复选框列表项。

适用于

另请参阅