设计模式：策略模式

策略模式（Strategy）：它定义了算法家族，分别封装起来，让它们这件可以相互替换，此模式让算法的变化，不会影响到使用算法的客户。

namespace StrategyDesignPattern
{
    //抽象算法类
    public abstract class Strategy
    {
        //算法方法
        public abstract void AlgorithmInterface();
    }
    //具体算法A
    public class ConcreateStrategyA:Strategy
    {
        //算法A实现方法
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法A实现");
        }
    }
    //具体算法B
    public class ConcreateStrategyB : Strategy
    {
        //算法A实现方法
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法B实现");
        }
    }
    //上下文
    public class Context
    {
        Strategy Strategy;
        public Context(Strategy strategy)
        {
            Strategy = strategy;
        }
        //上下文接口
        public void ContextInterface()
        {
            Strategy.AlgorithmInterface();
        }
    }
}

测试代码：

        public void StrategyTest()
        {
            Context context;
            context = new Context(new ConcreateStrategyA());
            context.ContextInterface();

            context = new Context(new ConcreateStrategyB());
            context.ContextInterface();
        }

 策略与简单工厂结合：

        public Context(string type)
        {
            switch(type)
            {
                case "A":
                    Strategy = new ConcreateStrategyA();
                    break;
                case "B":
                    Strategy = new ConcreateStrategyB();
                    break;
            }
        }