/// <summary>
/// 馒头
/// </summary>
public class SteamedBread
{
/// <summary>
/// 构造方法
/// </summary>
public SteamedBread()
{ }
/// <summary>
/// 销售价格
/// </summary>
private double price=0.5;
public double Price
{
get { return price; }
set { price = value; }
}
}
产品对象建立好了,接下来是工厂对象:
/// <summary>
/// 工厂角色
/// </summary>
public class Factory
{
/// <summary>
/// 创建一个馒头(SteamedBread)对象
/// </summary>
/// <returns></returns>
public static SteamedBread CreateInstance()
{
return new SteamedBread();
}
}
如上就完成了一个简单工厂模式的简单实现,一个产品和一个工厂,工厂负责创建这个产品。
/// <summary>
/// 食品接口----扮演抽象产品角色
/// </summary>
public interface IFood
{
/// <summary>
/// 每种食品都有销售价格,这里应该作为共性提升到父类或是接口来
/// 由于我们只需要得到价格,所以这里就只提供get属性访问器
/// </summary>
double price{get;}
}
//------------------------------------------------------------------------------------
/// <summary>
/// 馒头
/// </summary>
public class SteamedBread:IFood
{
/// <summary>
/// 构造方法
/// </summary>
public SteamedBread()
{ }
public double price
{
get
{
return 0.5;
}
}
}
//------------------------------------------------------------------------------------
/// <summary>
/// 包子
/// </summary>
public class SteamedStuffed:IFood
{
public SteamedStuffed()
{ }
/// <summary>
/// 销售价格
/// </summary>
public double price
{
get
{
return 0.6; //0.6元一个
}
}
}
//------------------------------------------------------------------------------------
/// <summary>
/// 工厂角色
/// </summary>
public class Factory
{
/// <summary>
/// 创建一个馒头(SteamedBread)对象
/// </summary>
/// <returns></returns>
public static IFood CreateInstance(string key)
{
if (key == "馒头")
{
return new SteamedBread();
}
else
{
return new SteamedStuffed();
}
}
}
//------------------------------------------------------------------------------------
public class Client
{
public static void Main(string[] args)
{
//通过工厂创建一个产品的实例
IFood food = Factory.CreateInstance("馒头");
Console.WriteLine("馒头{0}元一个!", food.price);
food = Factory.CreateInstance("包子");
Console.WriteLine("包子{0}元一个!", food.price);
}
}
此时的设计就已经完全符合简单工厂模式的意图了。顾客(Client)对早餐店营业员(Factory)说,我要“馒头”,于是营业员便根据顾客所提供的数据(馒头),去众多食品中找,找到了然后就拿给顾客。
有些情况下Simple Factory可以由抽象产品角色扮演,一个抽象产品类同时是子类的工厂。也就是说,抽象产品角色扮演两种角色和职责,出了基本的定义还还兼任工厂角色的职责,负责产品的创建工作。这里我们在上面的例子基础上适当修改一下OK了,新建立一个抽象类(Evolution):
/// <summary>
/// 兼任抽象产品角色和工厂角色两种角色
/// </summary>
public abstract class Evolution
{
/// <summary>
/// 共性字段
/// </summary>
private double price;
public double Price
{
get { return price; }
set { price = value; }
}
public static Evolution CreateInstance(string key)
{
if (key == "馒头")
{
return new SteamedBread();
}
else
{
return new SteamedStuffed();
}
}
}
public class SteamedBread : Evolution
{
public SteamedBread()
{
this.Price = 0.5; //在构造方法里初始话属性的值
}
}
public class SteamedStuffed : Evolution
{
public SteamedStuffed()
{
this.Price = 0.6;
}
}
通过上面的演化,此时客户端的调用如下:
public class Client
{
public static void Main(string[] args)
{
Evolution el = Evolution.CreateInstance("包子");
Console.WriteLine("包子{0}元一个!", el.Price);
}
}