本人学Asp.Net不久,用的是C#写代码,在学习C#中发现很多初学者对继承和多态性不是特别的了解,因此作了这个例子,希望对您有所帮助,例子很简单 
     页面文件TestProfileClass2.aspx 
  <%@ Page Language="C#" ContentType="text/html" ResponseEncoding="gb2312" Src="profile2.cs" %> 
  <%@ Import Namespace="shai" %> 
  <html> 
  <head> 
  <style> 
  div{font:Arial, Helvetica, sans-serif; 
  background-color:#cccccc; 
  border-color:black; 
  border-width:1; 
  border-style:solid; 
  padding:10,10,10,10; 
  } 
  </style> 
  <script language="c#" runat="server"> 
  public void Page_Load(Object sender,EventArgs e) 
  { 
   Profile profile = new Profile(); 
   message.InnerHtml += "<u>Profile Class</u><br>"; 
   message.InnerHtml += "Firstname:"+profile.getFirstname()+"<br>"; 
   message.InnerHtml += "Lastname:"+profile.getLastname()+"<br>"; 
   message.InnerHtml += "Phone:"+profile.getPhonenumber()+"<br><br>";    
   profile.save();    
   ExtendedProfile extendedprofile = new ExtendedProfile(); 
   message.InnerHtml += "<u>ExtendedProfile Class</u></br>"; 
   message.InnerHtml += "Firstname:"+profile.getFirstname()+"<br>"; 
   message.InnerHtml += "Lastname:"+profile.getLastname()+"<br>"; 
   message.InnerHtml += "Phone:"+extendedprofile.getPhonenumber()+"<br>"; 
   message.InnerHtml += "Address1:"+extendedprofile.getAddress1()+"<br>"; 
   message.InnerHtml += "Address2:"+extendedprofile.getAddress2()+"<br>"; 
   message.InnerHtml += "City:"+extendedprofile.getCity()+"<br>"; 
   message.InnerHtml += "State:"+extendedprofile.getState()+"<br>"; 
   message.InnerHtml += "Postal:"+extendedprofile.getPostal()+"<br>"; 
   message.InnerHtml += "Description:"+extendedprofile.getDescription()+"<br>";    
   extendedprofile.save(); 
  } 
  </script> 
  <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> 
  <title></title> 
  </head> 
  <body style="font:Arial, Helvetica, sans-serif "> 
  <b><h3>简单的继承/多态例子</h3></b><br><br> 
  object output:<br> 
  <br> 
  <div id="message" runat="server" /> 
  </body> 
  </html>       
  类定义文件profile2.cs 
  using System; 
  using System.IO; 
  using System.Xml; 
  namespace shai //名称空间shai 
  { 
   interface ISaveData //定义一个接口ISaveData,他作为Profile的基类被继承,由于其有多态性的特点,可以被 
   { //不同类调用其中的方法,并修改 
   void save(); 
   }    
   public class Profile:ISaveData //定义类Profile 
   { 
   protected string _firstname; //里面包含三个属性,分别为_firstname、_lastname、phonenumber 
   protected string _lastname; 
   protected string _phonenumber;    
   public Profile() //为属性定义其中的初始值 
   { 
   _firstname = "Saidy"; 
   _lastname = "Chen"; 
   _phonenumber = "(010)88716990"; 
   }    
   public string getPhonenumber() //Profile类中的方法getP