給Asp.Net初學者的關于繼承和多態性的例子

2019-11-18 19:24:17

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來源：轉載

供稿：網友

本人學 asp.net不久，用的是C#寫代碼，在學習C#中發現很多初學者對繼承和多態性不是特別的了解，因此作了這個例子，希望對您有所幫助，例子很簡單

頁面文件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>簡單的繼承/多態例子</h3></b><br><br>
object output:<br>
<br>
<div id="message" runat="server" />
</body>
</html>

類定義文件profile2.cs
using System;
using System.IO;
using System.xml;
namespace shai     //名稱空間shai
{
interface ISaveData    //定義一個接口ISaveData，他作為Profile的基類被繼承，由于其有多態性的特點，可以被
{                                //不同類調用其中的方法，并修改
    void save();
}

public class Profile:ISaveData     //定義類Profile
{
    protected string _firstname;       //里面包含三個屬性，分別為_firstname、_lastname、phonenumber
    protected string _lastname;
    protected string _phonenumber;

public Profile()                            //為屬性定義其中的初始值
{
   _firstname = "Saidy";
   _lastname = "Chen";
   _phonenumber = "(010)88716990";
}

public string getPhonenumber()           //Profile類中的方法getPhonenumber()
{
   return _phonenumber;
}
public virtual void setPhonenumber(string phonenumber)
{
   _phonenumber = phonenumber;
}

public string getFirstname()                 //Profile類中的方法getFirstname()
{
   return _firstname;
}
public void setFirstname(string firstname)
{
   _firstname = firstname;
}

public string getLastname()                  //Profile類中的方法getLastname()
{
   return _lastname;
}
public void setLastname(string lastname)
{
   _lastname = lastname;
}

public virtual void save()            //調用ISaveData接口的save()方法
{
   //保存數據為Text格式
   FileStream fs = new FileStream("D://myweb2//profile2.txt",FileMode.Create,File access.Write);
   StreamWriter sw = new StreamWriter(fs);
   sw.WriteLine("Firstname:"+_firstname.ToString());
   sw.WriteLine("Lastname:"+_lastname.ToString());
   sw.WriteLine("Phone:"+_phonenumber.ToString());
   sw.Flush();
   sw.Close();
   fs.Close();
}
}

public class ExtendedProfile:Profile        建立Profile子類ExtendedProfile，他可以繼承Profile中的方法
{
    protected string _address1;                  //子類ExtendedProfile的屬性
    protected string _address2;
    protected string _city;
    protected string _state;
    protected string _postal;
    protected string _description;

public ExtendedProfile()                      //子類ExtendedProfile中屬性的初始值
{
   _address1 = "清華大學";
   _address2 = "清華大學物理實驗室";
   _city = "北京";
   _state = "北京";
   _postal = "100024";
   _description = "教授";
}

public override void setPhonenumber(string phonenumber)           //繼承類Profile中的setPhonenumber()方法
{                                                                                                 //setPhonenumber()方法的重載
   _phonenumber = phonenumber;
}

public string getAddress1()          //子類ExtendedProfile中的方法getAddress1()，以下類推
{
   return _address1;
}
public string getAddress2()
{
   return _address2;
}
public void setAddress(string address1,string address2)
{
   _address1 = address1;
   _address2 = address2;
}

public string getCity()
{
   return _city;
}
public void setCity(string city)
{
   _city = city;
}

public string getState()
{
   return _state;
}
public void setState(string state)
{
   _state = state;
}

public string getPostal()
{
   return _postal;
}
public void setPostal(string postal)
{
   _postal = postal;
}

public string getDescription()
{
   return _description;
}
public void setDescription(string description)
{
   _description = description;
}

public override void save()                //調用接口ISaveData()中的方法save()，save()方法的重載，由于多態性
{                                                       //子類ExtendedProfile可以自定義并修改save()方法
   string _document = "d://myweb2//saidy.xml";
   XmlTextWriter writer = null;           //保存為一個Xml文件
   try
   {
    writer = new XmlTextWriter(_document,null);
    writer.Formatting = Formatting.Indented;
    writer.WriteStartDocument(false);
    writer.WriteDocType("Profile",null,null,null);            //表示<!DOCTYPE Profile>
    writer.WriteStartElement("Profile");                         //生成根元素
    writer.WriteElementString("firstname",_firstname);   //生成子元素 <firstname>_firstname</firstname>
    writer.WriteElementString("lastname",_lastname);
    writer.WriteElementString("phonenumber",_phonenumber);
    writer.WriteElementString("address1",_address1);
    writer.WriteElementString("address2",_address2);
    writer.WriteElementString("city",_city);
    writer.WriteElementString("state",_state);
    writer.WriteElementString("postal",_postal);
writer.WriteEndElement();
writer.Flush();
writer.Close();
   }
   catch(Exception ee)
   {
     Console.WriteLine("Exception:{0}",ee.ToString());
   }
}
}
}