通过

HtmlInputText.OnPreRender(EventArgs) 方法

  • 参考

定义

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

引发 PreRender 事件。

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 方法，OnPreRender使其在自定义HtmlInputText服务器控件中将 MaxLength 属性设置为 30 个字符。

<%@ 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">
<script runat="server">

  void Page_Load(Object sender, EventArgs e) 
  {
    if (!Page.IsPostBack)
    {
      HtmlInputText1.Value = "Hello HtmlInputText World.";
    }
  }

  void HtmlInputText1_ServerChange(object sender, System.EventArgs e)
  {

    // Diplay the value of the selected HtmlInputText control.
    System.Web.UI.HtmlControls.HtmlInputText htmlInputText1 = (System.Web.UI.HtmlControls.HtmlInputText) sender;
    Div1.InnerHtml = "Change the preceding text to:<br />" + htmlInputText1.Value;

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlInputText OnPreRender Example</title>
  </head>

  <body>
    
    <form id="Form1" method="post" runat="server">

      <h3>Custom HtmlInputText OnPreRender Example</h3>

      <p>Make a change to the text, and then press the ENTER.<br />

      <aspSample:CustomHtmlInputTextOnPreRender 
        id="HtmlInputText1" 
        name="HtmlInputText1" 
        runat="server" 
        type="text"
        size="45"
        style="WIDTH: 305px; HEIGHT: 22px" 
        onserverchange="HtmlInputText1_ServerChange">

      </p>
      <br />
      <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">
<script runat="server">

  Sub Page_Load(sender As Object, e As EventArgs)

    If Not Page.IsPostBack Then

      HtmlInputText1.Value = "Hello HtmlInputText World."

    End If

  End Sub

  Sub HtmlInputText1_ServerChange(sender As Object, e As System.EventArgs)

    Dim htmlInputText1 As System.Web.UI.HtmlControls.HtmlInputText = CType(sender, System.Web.UI.HtmlControls.HtmlInputText)
    Div1.InnerHtml = "Change the preceding text to:<br />" & htmlInputText1.Value

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom HtmlInputText OnPreRender Example</title>
  </head>

  <body>
    <form id="Form1" method="post" runat="server">

      <h3>Custom HtmlInputText OnPreRender Example</h3>

      <p>Make a change to the text, and then press the ENTER.<br />

      <aspSample:CustomHtmlInputTextOnPreRender 
        id="HtmlInputText1" 
        name="HtmlInputText1" 
        runat="server" 
        type="text"
        size="45"
        style="WIDTH: 305px; HEIGHT: 22px" 
        onserverchange="HtmlInputText1_ServerChange">

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

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputTextOnPreRender : System.Web.UI.HtmlControls.HtmlInputText
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);

            // Set the HtmlInputText object's MaxLength property to 30 characters.
            this.MaxLength = 30;
        }
    }
}

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

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

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

        ' Set the HtmlInputText object's MaxLength property to 30 characters.
        Me.MaxLength = 30
    End Sub
End Class

注解

在 OnPreRender 呈现 HtmlInputText 控件之前调用 方法。 方法 OnPreRender 主要由扩展控件功能的 HtmlInputText 控件开发人员使用。

适用于