Strategy Pattern (1)

设计模式原则：

1. 变化的部分进行封装

2. 组合>继承

3. 面向接口编程而不是面向实现编程

策略模式：

　　定义一系列算法并将其封装，使其具有通用的调用方法。策略模式让算法的变化与客户端代码使用它的方法相互独立。

示例代码：

namespace Hello
{
    //主板抽象类，不变的代码
    public abstract class MainBoard
    {
        public CPU cpu;
        public GPU gpu;

        public MainBoard() {}

        public void RunCPU()
        {
            cpu.CPUStart();
        }
        
        public void RunGPU()
        {
            gpu.GPUStart();
        }

        public abstract void ShowCompany();
    }
    //CPU接口
    public interface CPU
    {
        void CPUStart();
    }

    public class IntelCPU : CPU
    {
        public void CPUStart()
        {
            Console.WriteLine("Intel CPU is running!");
        }
    }

    public class AMDCPU : CPU
    {
        public void CPUStart()
        {
            Console.WriteLine("AMD CPU is running!");
        }
    }
    //GPU接口
    public interface GPU
    {
        void GPUStart();
    }

    public class NVIDIAGPU : GPU
    {
        public void GPUStart()
        {
            Console.WriteLine("NVIDIA GPU is running!");
        }
    }

    public class ATIGPU : GPU
    {
        public void GPUStart()
        {
            Console.WriteLine("ATI GPU is running!");
        }
    }
    //新主板
    public class IntelBoard : MainBoard
    {
        public IntelBoard()
        {
            cpu = new IntelCPU();
            gpu = new NVIDIAGPU();
        }

        public override void ShowCompany()
        {
            Console.WriteLine("Board from Intel.");
        }
    }
    //新主板
    public class AMDBoard : MainBoard
    {
        public AMDBoard()
        {
            cpu = new AMDCPU();
            gpu = new ATIGPU();
        }

        public override void ShowCompany()
        {
            Console.WriteLine("Board from AMD.");
        }
    }
    //开始测试
    class Program
    {
        static void Main(string[] args)
        {
            MainBoard mainBoard = new IntelBoard();
            mainBoard.ShowCompany();
            mainBoard.RunCPU();
            mainBoard.RunGPU();

            mainBoard = new AMDBoard();
            mainBoard.ShowCompany();
            mainBoard.RunCPU();
            mainBoard.RunGPU();
        }
    }
}