Head First 设计模式----StrategyPattern

策略模式定义了算法族，分别封装起来，让它们之间可以互相替换，此模式让算法的变化独立于使用算法的客户

Interface

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace StrategyPattern.Interface
{
    public interface FlyBehavior
    {
        void fly();
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace StrategyPattern.Interface
{
    public interface QuackBehavior
    {
        void quack();
    }
}

Behavior

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;

namespace StrategyPattern.Behavior
{
    //实现了所有不会飞鸭子的动作
    public class FlyNoWay:FlyBehavior
    {
        public void fly()
        {
            Console.WriteLine("I can‘t fly");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;

namespace StrategyPattern.Behavior
{
    //利用火箭动力的飞行行为
    public class FlyRocketPowered:FlyBehavior
    {
        public void fly()
        {
            Console.WriteLine("I‘m flying with a rocket!");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;
namespace StrategyPattern.Behavior
{
    //实现了所有有翅膀鸭子的飞行动作
    public class FlyWithWings:FlyBehavior
    {
        public void fly()
        {
            Console.WriteLine("I‘m flying!");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;
namespace StrategyPattern.Behavior
{
    //名为呱呱叫，其实不出声
    public class MuteQuack:QuackBehavior
    {
        public void quack()
        {
            Console.WriteLine("<< Silence >>");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;
namespace StrategyPattern.Behavior
{
    //呱呱叫
    public class Quack:QuackBehavior
    {
        public void quack()
        {
            Console.WriteLine("Quack");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;
namespace StrategyPattern.Behavior
{
    //名为呱呱叫，实为吱吱叫
    public class Squeak:QuackBehavior
    {
        public void quack()
        {
            Console.WriteLine("Squeak");
        }
    }
}

使用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Interface;

namespace StrategyPattern
{
    public abstract class Duck
    {
        protected FlyBehavior flyBehavior;
        protected QuackBehavior quackBehavior;

        public abstract void display();

        public void performFly()
        {
            flyBehavior.fly();
        }
        public void performQuack()
        {
            quackBehavior.quack();
        }
        public void swim()
        {
            Console.WriteLine("All ducks float, even decoys!");
        }

        public void setFlyBehavior(FlyBehavior fb)
        {
            flyBehavior = fb;
        }
        public void setQuackBehavior(QuackBehavior qb)
        {
            quackBehavior = qb;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Behavior;

namespace StrategyPattern
{
    //绿头鸭（一种野鸭）
    public class MallardDuck:Duck
    {
        public MallardDuck()
        {
            quackBehavior = new Quack();
            flyBehavior = new FlyWithWings();
        }
        public override void display()
        {
            Console.WriteLine("I‘m a real Mallard duck");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using StrategyPattern.Behavior;
namespace StrategyPattern
{
    //模型鸭
    public class ModelDuck:Duck
    {
        public ModelDuck()
        {
            flyBehavior = new FlyNoWay();
            quackBehavior = new Quack();
        }
        public override void display()
        {
            Console.WriteLine("I‘m a model duck");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace StrategyPattern
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Test Mallard Duck");
            Duck mallard = new MallardDuck();
            mallard.performFly();
            mallard.performQuack();

            Console.WriteLine("Test Model Duck");
            Duck model = new ModelDuck();
            model.performFly();
            model.setFlyBehavior(new StrategyPattern.Behavior.FlyRocketPowered());
            model.performFly();

            //Stop
            Console.ReadLine();
        }
    }
}