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设计模式一 - Simple Factory, Factory Method, Abstract Factory以及Builder模式简述

 2010-02-02 10:46:33 来源:WEB开发网   
核心提示:虽然现在博客园上关于设计模式的文章已经有很多,但还是写一篇来凑下热闹,设计模式一 - Simple Factory, Factory Method, Abstract Factory以及Builder模式简述,也算是对自己多这几种模式得使用总结,Factory Pattern 工厂模式和 Builder Patter
虽然现在博客园上关于设计模式的文章已经有很多,但还是写一篇来凑下热闹,也算是对自己多这几种模式得使用总结。

Factory Pattern 工厂模式和 Builder Patter 建造者模式都是通过定义接口来将类的定义和实现区分开来。下面一步一步来做说明



1. Simple Factory 简单工厂

简单工厂只是将类简单抽象化,以Pizza为例,我们定义好Pizza的接口,实现继承Pizza的类PizzaA和PizzaB,然后简单工厂提供方法根据传进来的参数类型确定像调用者返回PizzaA或者PizzaB的实例



代码
  public interface Pizza
  {
    void DoPizza();
  }

  public class PizzaA : Pizza
  {
    public void DoPizza()
    {
      Console.WriteLine("pizza A");
    }
  }

  public class PizzaB : Pizza
  {
    public void DoPizza()
    {
      Console.WriteLine("pizza B");
    }
  }
  public static class SimplePizzaFacotry
  {
    public static Pizza Create(string type)
    {
      if (type == "PizzaA")
        return new PizzaA();
      else
        return new PizzaB();
    }
  }

  // Usage
  public class SimplePizzaFacotryOrder
  {
    public void OrderPizza()
    {
      Pizza pizza = SimplePizzaFacotry.Create("PizzaA");
      pizza.DoPizza();
    }
  }




2. Factory Method工厂方法

工厂方式是在简单工厂模式基础上进一步抽象来符合OO设计的要求。这里将Factory抽象化为接口或抽象类,然后继承类负责具体实现。此时增加一个FactoryManage来负责返回那个工厂类实现的实例。代码示例如下

代码
// Pizza, PizzaA, PizzaB继续使用简单工厂定义

  public abstract class PizzaFactory
  {
    public abstract Pizza Create();
  }

  public class PizzaAFactory : PizzaFactory
  {
    public override Pizza Create()
    {
      return new PizzaA();
      //throw new NotImplementedException();
    }
  }

  public class PizzaBFactory : PizzaFactory
  {
    public override Pizza Create()
    {
      return new PizzaB();
      //throw new NotImplementedException();
    }
  }

  public abstract class PizzaMethodManager
  {
    public static PizzaFactory Factory = new PizzaAFactory();
  }
  
  //usage
  public class FactoryMethodPizzaOrder
  {
    public FactoryMethodPizzaOrder()
    {
      Pizza pizza = PizzaMethodManager.Factory.Create();
    }
  }


 3. Abstract Factory 抽象工厂

抽象工厂和工厂方法基本上一样,区别在于此时抽象工厂可以来实现一系列相关类的实现。继续用Pizza举例,这里将Pizza分为Dough和Sauce即面团和酱,然后定义HutPizza和PapaPizza的面团Dougn, Sauce以及Pizza的实现。示例如下

代码
  public interface IDough
  {
    void DoDough();
  }

  public interface ISauce
  {
    void DoSauce();
  }

  public class PapaDough : IDough
  {
    public void DoDough()
    {
      Console.WriteLine("Papa Jone's Dough");
    }
  }

  public class PapaSource : ISauce
  {
    public void DoSauce()
    {
      Console.WriteLine("Papa Jone's Sauce");
    }
  }

  public class HutDough : IDough
  {
    public void DoDough()
    {
      Console.WriteLine("Pizza Hut's Dough");
    }
  }

  public class HutSource : ISauce
  {
    public void DoSauce()
    {
      Console.WriteLine("Pizza Hut's Sauce");
    }
  }

  public interface ipizzaFactory
  {
    IDough PRepareDough();
    ISauce AddSauce();
  }

  public class PapaPizzaFacotry : IPizzaFactory
  {
    public IDough PrepareDough()
    {
      return new PapaDough();
    }

    public ISauce AddSauce()
    {
      return new PapaSource();
    }
  }

  public class HutPizzaFacotry : IPizzaFactory
  {
    public IDough PrepareDough()
    {
      return new HutDough();
    }

    public ISauce AddSauce()
    {
      return new HutSource();
    }
  }

  public abstract class AbstractPizzaManager
  {
    public static IPizzaFactory Facotry = new PapaPizzaFacotry();
  }

  // Usage
  public class OrderPizzaAbstract
  {
    public void OrderPizza()
    {
      IDough dough = AbstractPizzaManager.Facotry.PrepareDough();
      ISauce sauce = AbstractPizzaManager.Facotry.AddSauce();
      dough.DoDough();
      sauce.DoSauce();
    }
  }



 

4. Builder Pattern 建造者模式

Builder和抽象工厂类似,也是建立一系列对象的实现。区别在于Builder建立的一对象有依赖关系而Factory的对象只是有关联。依旧以Pizza为例,pizza的做法是先做面团(饼底),然后放Sauce(Cheese或者其他的东西),然后放Topping(火腿,香肠之类的)。举例如下

代码
  class PizzaBD
  {
    public string Dough { get; set; }
    public string Sauce { get; set; }
    public string Topping { get; set; }
  }
   
  abstract class PizzaBuilder
  {
    public PizzaBD pizza { get; protected set; }
   
    public void CreatePizza()
    {
      pizza = new PizzaBD();
    }
   
    public abstract void BuildDough();
    public abstract void BuildSauce();
    public abstract void BuildTopping();
  }
   
  class HawaiianPizzaBuilder : PizzaBuilder
  {
    public override void BuildDough()
    {
      pizza.Dough = "Cross";
    }
   
    public override void BuildSauce()
    {
      pizza.Sauce = "Mild";
    }
   
    public override void BuildTopping()
    {
      pizza.Topping = "Ham+Pineapple";
    }
  }
   
  class SpicyPizzaBuilder : PizzaBuilder
  {
    public override void BuildDough()
    {
      pizza.Dough = "Pan Baked";
    }
   
    public override void BuildSauce()
    {
      pizza.Sauce = "Hot";
    }
   
    public override void BuildTopping()
    {
      pizza.Topping = "Pepperoni+Salami";
    }
  }
   
  class Cook
  {
    public PizzaBuilder PizzaBuilder { get; set; }

    public PizzaBD Pizza { get { return PizzaBuilder.pizza; } }
   
    public void MakePizza()
    {
      PizzaBuilder.CreatePizza();
      PizzaBuilder.BuildDough();
      PizzaBuilder.BuildSauce();
      PizzaBuilder.BuildTopping();
    }
  }
   
  // usage
  public class CallBuilder
  {
    public void OrderPizza()
    {
      Cook cook = new Cook();
      cook.PizzaBuilder = new SpicyPizzaBuilder();
      cook.MakePizza();
      cook.PizzaBuilder = new HawaiianPizzaBuilder();
      cook.MakePizza();
    }
  }


 5. Facade Pattern 外观模式

提到了Builder模式,也就顺便提一下Facade模式。两者类似处在于都是建立一系列对象,区别在于Builder模式创建一系列有依赖关系的子类,而Facade模式则是建立一个将复杂的子类简化和集中化的通道。还是以Pizza为例,客户吃完付款,需要Waiter收取现金/卡,然后财务做账/transfer之后打印发票,返回。对客户来说后端多的一系列动作他并不关心,PizzaPayFacade提供给客户一个Pay方法,方法里面完成这一系列的动作[可能包括类的实现]。代码稍后提供。大家可以先参考First We try, then we trust的Facade说明的代码示例 http://www.cnblogs.com/zhenyulu/articles/55992.html

Tags:设计模式 Simple Factory

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