大话设计模式 - 简单工厂模式和策略模式

策略模式是一种定义一系列算法的方法, 从概念上看, 所有这些算法完成的都是相同的工作, 只是实现不同, 它可以以相同的方式调用所有的算法, 减少各种算法类与使用算法类之间的耦合.
与简单工厂不同的是, 策略模式将不同的子类算法(接口一样)抽象成一个类. 不同的初始化参数可以调用不同的算法. 而简单工厂是根据不同的初始化参数返回不同的子类对象.

收银机的主要代码 Form1.cs :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace StrategyMethod
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        double total = 0.0d;
        private void button_OK_Click(object sender, EventArgs e)
        {
            CashSuper csuper = CashFactory.createCashAccept(comboBox1.SelectedItem.ToString());
            double totalPrices = 0d;
            totalPrices = csuper.acceptCash(Convert.ToDouble(textBox_price.Text))
                * Convert.ToDouble(textBox_num.Text);
            total = total + totalPrices;
            listBoxList.Items.Add("单价: " + textBox_price.Text + " 数量: " + textBox_num.Text + " "
                + comboBox1.SelectedItem + " 合计: " + totalPrices.ToString());

            label_total.Text = total.ToString();
        }

        private void button_Reset_Click(object sender, EventArgs e)
        {
            CashContext cc = null;
            switch (comboBox1.SelectedItem.ToString())
            {
                case "正常收费":
                    cc = new CashContext(new CashNormal());
                    break;
                case "满300减100":
                    cc = new CashContext(new CashReturn("300", "100"));
                    break;
                case "打8折":
                    cc = new CashContext(new CashRebate("0.8"));
                    break;
            }

            double totalPrices = 0d;
            totalPrices = cc.GetResult(Convert.ToDouble(textBox_price.Text))
                * Convert.ToDouble(textBox_num.Text);
            total = total + totalPrices;
            listBoxList.Items.Add("单价: " + textBox_price.Text + " 数量: " + textBox_num.Text + " "
                + comboBox1.SelectedItem + " 合计: " + totalPrices.ToString());

            label_total.Text = total.ToString();
        }

        private void label1_Click(object sender, EventArgs e)
        {

        }
    }
    // 收款抽象基类
    abstract class CashSuper
    {
        public abstract double acceptCash(double money);
    }
    // 正常收费子类
    class CashNormal : CashSuper
    {
        public override double acceptCash(double money)
        {
            return money;
        }
    }
    // 打折收费子类
    class CashRebate: CashSuper
    {
        private double moneyRebate = 1d;
        public CashRebate(string moneyRebate)
        {
            this.moneyRebate = double.Parse(moneyRebate);
        }
        public override double acceptCash(double money)
        {
            return moneyRebate * money;
        }
    }
    // 返利收费子类
    class CashReturn: CashSuper
    {
        private double moneyCondition = 0.0d;
        private double moneyReturn = 0.0d;
        public CashReturn(string moneyCondition, string moneyReturn)
        {
            this.moneyCondition = double.Parse(moneyCondition);
            this.moneyReturn = double.Parse(moneyReturn);
        }
        public override double acceptCash(double money)
        {
            double result = money;
            if (money >= moneyCondition)
            {
                result = money - Math.Floor(money / moneyCondition) * moneyReturn;
            }

            return result;
        }
    }
    // 现金收费工厂类
    class CashFactory
    {
        public static CashSuper createCashAccept(string type)
        {
            CashSuper cs = null;
            switch(type)
            {
                case "正常收费":
                    cs = new CashNormal();
                    break;
                case "满300返100":
                    CashReturn cr1 = new CashReturn("300", "100");
                    cs = cr1;
                    break;
                case "打8折":
                    CashRebate cr2 = new CashRebate("0.8");
                    cs = cr2;
                    break;
            }
            return cs;
        }
    }

    // 策略模式
    class CashContext
    {
        private CashSuper cs;
        public CashContext(CashSuper csuper)
        {
            this.cs = csuper;
        }
        public double GetResult(double money)
        {
            return cs.acceptCash(money);
        }
    }

}