strategy.cs

C#设计模式源码

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

namespace DesignDll
{

    /*
     * 策略模式（Strategy）操作
     * 它定义了算法家族，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，不会影响到使用算法的客户
     */
    //以下样例有采用策略模式，加上简单工厂模式来处理。
    /// <summary>
    /// 定义一个抽象类
    /// </summary>
    public abstract class Strategy
    {
        private double _price = 0;
        private int _count = 0;
        /// <summary>
        /// 单价
        /// </summary>
        public double Price
        {
            get { return _price; }
            set { _price = value; }
        }
        /// <summary>
        /// 数量
        /// </summary>
        public int Count
        {
            get { return _count; }
            set { _count = value; }
        }

        public abstract void  AlgorithmInterface();
        //计算方法的结果相当提供一个接口
        public abstract double GetResultInterface(double dPrice , int iCount);
    }

    /// <summary>
    /// 具体算法/功能
    /// </summary>
    public class ConcreateStragegyA : Strategy
    {
        public override void AlgorithmInterface()
        {
            //实现A的算法
            //throw new Exception("The method or operation is not implemented.");
        }

        /// <summary>
        /// 实现正常收费功能 单价*数量
        /// </summary>
        /// <returns></returns>
        public override double GetResultInterface(double dPrice , int iCount)
        {
            return dPrice * iCount;
            //throw new Exception("The method or operation is not implemented.");
        }
    }

    /// <summary>
    /// 具体算法/功能 
    /// </summary>
    public class ConcreateStragegyB : Strategy
    {
        public override void AlgorithmInterface()
        {
            //实现B的算法
            //throw new Exception("The method or operation is not implemented.");
        }

        /// <summary>
        /// 打打9折优惠
        /// </summary>
        /// <returns></returns>
        public override double GetResultInterface(double dPrice, int iCount)
        {
            return dPrice * iCount * 0.9;
             //throw new Exception("The method or operation is not implemented.");
        }
    }

    /// <summary>
    /// 具体算法功能
    /// </summary>
    public class ConcreateStragegyC : Strategy
    {
        public override void AlgorithmInterface()
        {
            //实现C的算法
            //throw new Exception("The method or operation is not implemented.");
        }

        /// <summary>
        /// 打7.5折优惠
        /// </summary>
        /// <returns></returns>
        public override double GetResultInterface(double dPrice, int iCount)
        {
            return dPrice * iCount * 0.75;
            //throw new Exception("The method or operation is not implemented.");
        }
    }


    /// <summary>
    /// 具体算法/功能 
    /// </summary>
    public class ConcreateStragegyD : Strategy
    {
        public override void AlgorithmInterface()
        {
            throw new Exception("The method or operation is not implemented.");
        }

        public override double GetResultInterface(double dPrice, int iCount)
        {
            return dPrice * iCount * 0.5;
            //throw new Exception("The method or operation is not implemented.");
        }
    }

    /// <summary>
    /// 用来管控操作
    /// </summary>
    public class Context
    {
        Strategy strategy;
        //定义构造函数
        public Context(int itype)
        {
            switch(itype)
            {
                case 0:
                    this.strategy = new ConcreateStragegyA();
                    break;
                case 1:
                    this.strategy = new ConcreateStragegyB();
                    break;
                case 2:
                    this.strategy = new ConcreateStragegyC();
                    break;
                case 3:
                    this.strategy = new ConcreateStragegyD();
                    break;
            }
        }


        /// <summary>
        /// 结合上下文的接口
        /// </summary>
        public void ContextInterface()
        {
            strategy.AlgorithmInterface();
        }


        public double ContextResultInterface(double dPrice, int iCount)
        {
            if (strategy != null)
                return strategy.GetResultInterface(dPrice, iCount);
            else
                return 0;
        }
    }


}