小故事学设计模式之Observer : (三) 老婆帮忙订机票

(IT的事就是过场多,过场多了就容易忘,所以我们不妨看一个记一个,这也是一个办法,顺便还能跟同行们交流一下) 

要和老婆一起回老家了, 成都离我们安徽太远, 两个人飞一下过去就要花掉近三千块, 于是我们决定找找有没有更便宜的机票,

"你帮我找找吧, 如果找到的话,跟我说一下",我说道.

"行!"老婆记住了这事.

很快我得到通知, 南航有更便宜的, 580块.

这是一个简单的observer模式.

什么是observer? 其定义如下:

The Observer Patern defines a one-to-many dependency betwen objects so that when one object changes state, all its dependents are notified and updated automatically.

大概结构来描述就如下:

其中Neo(就是我以前在IT混日子的马甲拉)是继承于TicketBuyer这个抽象类的, 为什么这里要加一个抽象类,因为老婆表兄妹多, 都有可能找她订票, 所以要把这些表兄妹的行为抽象到一个公共的抽象类上.

using System;
using System.Collections.Generic;

public abstract class TicketBuyer
{
    public int TicketPrice;
    public string Airline;
}

public class Neo: TicketBuyer
{
    private int _ticketPrice;
    private string _airline;

    public int TicketPrice
    {
        get {return _ticketPrice;}
        set {_ticketPrice = value;}
    }

    public string Airline
    {
        get{return _airline;}
        set{_airline = value;}
    }
}
public class FeiFei
{
    private string _airline;
    private int _ticketPrice;

    IList<TicketBuyer> _ticketBuyers;

    public FeiFei()
    {
        _ticketBuyers = new List<TicketBuyer>();
    }

    public void AddTicketBuyer(TicketBuyer t)
    {
        _ticketBuyers.Add(t);
    }

    public void DeleteTicketBuyer(TicketBuyer t)
    {
        _ticketBuyers.Remove(t);
    }

    public void NotifyTicketInformation()
    {
        SearchTicket();
        foreach(TicketBuyer t in _ticketBuyers)
        {
            t.Airline = _airline;
            t.TicketPrice = _ticketPrice;
        }
    }

    private void SearchTicket()
    {
        _airline = "China Southern";
        _ticketPrice = 580;
    }
}

运行代码看一下结果：

public class Test
{
    public static void Main()
    {
        TicketBuyer n = new Neo();
        FeiFei f = new FeiFei();
        f.AddTicketBuyer(n);
        f.NotifyTicketInformation();
        Console.WriteLine("Airline:" + n.Airline + ", price:" + n.TicketPrice);
        Console.Read();
    }
}

好了，以上是个人对Observer模式的理解，如有不正确的地方，希望同行能帮我纠正。

谢谢大家！