策略模式（Stratety）

namespace StrategyPattern //策略模式
{
    /// <summary>
    /// 定义所以支持的算法的公共接口
    /// </summary>
    abstract  class Strategy
    {
        /// <summary>
        /// 算法方法。
        /// </summary>
        public abstract void AlgorithmInrerface();
    }

    class ConcreateStratetyA : Strategy
    {
        public override void AlgorithmInrerface()
        {
            Console.WriteLine("实现算法A");
        }
    }

    class ConcreateStratetyB : Strategy
    {
        public override void AlgorithmInrerface()
        {
            Console.WriteLine("实现算法B");
        }
    }

    class ConcreateStratetyC : Strategy
    {
        public override void AlgorithmInrerface()
        {
            Console.WriteLine("实现算法C");
        }
    }

    /// <summary>
    /// 用一个ConcreateStratety来配置，来维护一个对Stratety对象的引用。
    /// </summary>
    class Context
    {
        Strategy stratety;
        public Context(Strategy stratety)//构造器注入具体的策略对象。
        {
            this.stratety = stratety;
        }
        /// <summary>
        /// 根据具体策略的对象，调用其算法的方法。
        /// </summary>
        public void ContextInterface()
        {
            stratety.AlgorithmInrerface();
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Context context = null;

            context = new Context(new ConcreateStratetyA());
            context.ContextInterface();

            context = new Context(new ConcreateStratetyB());
            context.ContextInterface();

            context = new Context(new ConcreateStratetyC());
            context.ContextInterface();

            Console.Read();
        }
    }
}