通过

HtmlInputCheckBox.OnPreRender(EventArgs) 方法

  • 参考

定义

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

引发 OnPreRender(EventArgs) 事件并将该控件注册为需要回发处理的控件。

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 OnPreRender 自定义服务器控件中的 方法， Title 以便将属性添加到每个 HtmlInputCheckBox 控件。

<%@ 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 HtmlInputCheckBox - OnPreRender - C# Example</title>
    <script runat="server">
      void Button1_Click(Object sender, EventArgs e)
      {
        Div1.InnerHtml = "";

        if(HtmlInputCheckBox1.Checked == true)
        {
          Div1.InnerHtml = "You like basketball. ";
        }

        if(HtmlInputCheckBox2.Checked == true)
        {
          Div1.InnerHtml += "You like football. ";
        }

        if(HtmlInputCheckBox3.Checked == true)
        {
          Div1.InnerHtml += "You like soccer. ";
        }
      }
    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - C# Example</h3>
      <br />
      Enter Interests:<p>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </p>
      <p>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        onserverclick="Button1_Click"
        name="Button1" />
      </p>

      <div id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
    </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 HtmlInputCheckBox - OnPreRender - Visual Basic Example</title>
    <script runat="server">
      Sub Button1_Click(sender As Object, e As EventArgs)
        Div1.InnerHtml = ""

        If HtmlInputCheckBox1.Checked = True Then
            Div1.InnerHtml = "You like basketball. "
        End If

        If HtmlInputCheckBox2.Checked = True Then
            Div1.InnerHtml += "You like football. "
        End If

        If HtmlInputCheckBox3.Checked = True Then
            Div1.InnerHtml += "You like soccer. "
        End If
      End Sub

    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - Visual Basic Example</h3>
      <br />
      Enter Interests:<p>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </p>
      <p>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        onserverclick="Button1_Click"
        name="Button1" />
      </p>

      <br />
      <div id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
        ms_positioning="FlowLayout" />
    </form>
  </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputCheckBoxOnPreRender : System.Web.UI.HtmlControls.HtmlInputCheckBox
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);
            
            // Add a Title attribute to each HtmlInputCheckBox.
            this.Attributes.Add("title", "If you like " + this.Value + ", then select this check box.");
        }
    }
}

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls

    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomHtmlInputCheckBoxOnPreRender
        Inherits System.Web.UI.HtmlControls.HtmlInputCheckBox

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

            ' Call the base class's OnPreRender method.
            MyBase.OnPreRender(e)

            ' Add a Title attribute to each HtmlInputCheckBox.
            Me.Attributes.Add("title", "If you like " + Me.Value + ", then select this check box.")
        End Sub
    End Class

End Namespace

注解

方法 OnPreRender 重写基 OnPreRender 方法。 OnPreRender 主要由控件开发人员使用。

适用于