设计模式学习笔记-策略模式

策略模式：Strategy,它定义了算法家族，分别封装起来，让他们之间可以相互替换，让算法的变化不会影响到算法使用者

1.定义抽象算法

    /// <summary>
    /// 抽象算法类
    /// </summary>
    abstract class Strategy
    {
        /// <summary>
        /// 算法方法 接口定义
        /// </summary>
        public abstract void AlgorithmInterface();
    }

2.具体算法的实现

  /// <summary>
    /// 具体算法A
    /// </summary>
    class ConcreteStrategyA : Strategy 
    {
        public override void AlgorithmInterface() 
        {
            Console.WriteLine("算法A的实现");
        }
    }
    /// <summary>
    /// 具体算法B
    /// </summary>
    class ConcreteStrategyB : Strategy
    {
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法B的实现");
        }
    }
    /// <summary>
    /// 具体算法C
    /// </summary>
    class ConcreteStrategyC : Strategy
    {
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法C的实现");
        }
    }

3.调度类

    /// <summary>
    /// 承上启下的算法调用
    /// </summary>
    class Context 
    {
        Strategy strategy;
        /// <summary>
        /// 传入具体策略对象
        /// </summary>
        /// <param name="strategy"></param>
        public Context(Strategy strategy) 
        {
            this.strategy = strategy;
        }
        /// <summary>
        /// 根据策略对象的值判断调用的算法类
        /// </summary>
        public void ContextInterface() 
        {
            strategy.AlgorithmInterface();
        }
    }

　　客户端调用：

        /// <summary>
        /// 测试策略
        /// </summary>
        static void TestStrategy() 
        {
            Context context;
            //策略A
            context = new Context(new ConcreteStrategyA());
            context.ContextInterface();
            //策略B
            context = new Context(new ConcreteStrategyB());
            context.ContextInterface();
            //策略C
            context = new Context(new ConcreteStrategyC());
            context.ContextInterface();
            Console.Read();
        }