设计模式应用(房屋销售-----一次笔试时的试题)

一次去参加一房地产管理系统的公司面试时，碰到一道设计模式的题，大意就是公司有多种房型，包括公寓，别墅等，另

外，销售人员每售出一套房子时，公司的高管就会收到消息。

 

初步分析题意，要用到观察者模式(通知公司高管)，还有就是工厂模式(公司有多种房型)当然也可以是策略模式的。

 

UML类图如下所示：

 

 

代码如下：

首先是简单工厂的一些类

房子类

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 抽象的House类 /// </summary> public abstract class House { //房子类型 private string houseType; //房子价格 private double housePrice; public string HouseType { get { return houseType; } set { if (houseType != value) { houseType = value; } } } public double HousePrice { get { return housePrice; } set { if (housePrice != value) { housePrice = value; } } } }}

房子类型：

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 定义该公司的房子的所有类型 /// </summary> public class TypeOfHouse { public static string apartment = "apartment"; public static string villa = "villa"; }}

 

公寓类

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 公寓 /// </summary> public class Apartment : House { public Apartment(double price) { this.HouseType = TypeOfHouse.apartment; this.HousePrice = price; } }}

 

别墅类

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 公寓 /// </summary> public class Apartment : House { public Apartment(double price) { this.HouseType = TypeOfHouse.apartment; this.HousePrice = price; } }}

 

销售房子的工厂类

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ public class HouseFactory { public static House createSellingHouse(string houseType, double housePrice) { House house = null; switch (houseType) { case "apartment"://想在这里用TypeOfHouse.apartment,但这不是常量，不能用 house = new Apartment(housePrice); break; case "villa": house = new Villa(housePrice); break; //default: // Console.WriteLine("there is not this kind of house"); } return house; } }}

 

接下来就是Observer Pattern的类了

主题类

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 主题类 /// </summary> public abstract class Subject { public abstract void addObserver(Observer o); public abstract void removeObserver(Observer o); public abstract void notifyObservers(); public abstract void sellHouse(string houseType, double housePrice); }}

 

观察者类

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 观察者类 /// </summary> public abstract class Observer { public abstract void update(string houseType, double housePrice); }}

 

具体的观察者

 using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ /// <summary> /// 公司高层，经理类 /// </summary> public class Manager: Observer { public override void update(string houseType, double housePrice) { Console.WriteLine("to manager: A {0} is sold at price of {1}", houseType, housePrice); } }}

 

当然这里还可以建立一个BOSS类，内容和经理类差不多。

 

具体的主题类(不晓得这里处理得对不对，小弟初学设计模式)

using System;using System.Collections.Generic;using System.Text;using System.Collections;namespace RealEstate{ /// <summary> /// 销售人员 /// </summary> public class SellsMan : Subject { private ArrayList aryLst; private House house; public override void sellHouse(string houseType, double housePrice) { house = HouseFactory.createSellingHouse(houseType, housePrice); house.HousePrice = housePrice; house.HouseType = houseType; Console.WriteLine("to sells man: A {0} is sold at price of {1}", houseType, housePrice); notifyObservers(); } public SellsMan() { aryLst = new ArrayList(); } public override void addObserver(Observer o) { aryLst.Add(o); } public override void removeObserver(Observer o) { int i = aryLst.IndexOf(o); if (i >= 0) { aryLst.RemoveAt(i); } } public override void notifyObservers() { foreach (Observer o in aryLst) { o.update(house.HouseType, house.HousePrice); } } }}

 

最后是MAIN函数了

using System;using System.Collections.Generic;using System.Text;namespace RealEstate{ class Program { static void Main(string[] args) { SellsMan sellsMan = new SellsMan(); Manager mgr = new Manager(); sellsMan.addObserver(mgr); sellsMan.sellHouse(TypeOfHouse.apartment, 12); } }}

 

运行结果如下：

 

最近一直在学习设计模式 ，今天就拿这个面试题作为例子来练手，也不晓得是不是最好的方法。

 

参考资料：

head first to design pattern

大话设计模式(小菜大鸟版)