Codeusing System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
namespace myControls
{
/// <summary>
/// 把这个类要放在app_code文件夹中,所有加入到这个特殊文件夹中的类都会被asp.net Framework编译
/// LengthValidator 的摘要说明,要继承BaseValidator类,这是一个抽象类,要实现一个方法EvaluateIsValid(),当被
/// 检验的表单字段通过验证时返回true.
/// BaseValidator类也包含其它一些方法,其中GetControlValidationValue()用于获取被验证的控件的值
/// </summary>
public class LengthValidator : BaseValidator
{
/// <summary>
/// 构造
/// </summary>
public LengthValidator()
{
}
//属性值,长度
private int maximunLength = 0;
public int MaximunLength
{
get { return maximunLength; }
set { maximunLength = value; }
}
/// <summary>
/// 重写父类的方法
/// </summary>
/// <returns></returns>
protected override bool EvaluateIsValid()
{
string value = this.GetControlValidationValue(this.ControlToValidate);
if (value.Length > maximunLength)
{
return false;
}
return true;
}
}
}
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register TagPrefix="custom" Namespace="myControls" %>
<%-- 用Register指令注册LengthValidator控件 --%>
<!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 runat="server">
<title>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TextBox ID="txtVal" runat="server"></asp:TextBox>
<custom:LengthValidator ID="valId" MaximunLength="10" ControlToValidate="txtVal" Text="必须小于10个字符" runat="server" />
<asp:Button ID="Button1" runat="server" Text="Button" /></div>
</form>
</body>
</html>
