策略模式學習代碼(用反射實現超市收銀功能)

 //後臺代碼

namespace Calculator
{
    //商場管理策略模式(反射)
    public partial class Shop : Form
    {
        public Shop()
        {
            InitializeComponent();
        }

        DataSet ds;             //用於存放配置文件信息
        double total = 0.0d;    //用於總計

        private void Shop_Load(object sender, EventArgs e)
        {
            //讀取配置文件
            ds = new DataSet();
            ds.ReadXml(Application.StartupPath+"\\CashAcceptType.xml");
            //將讀取到的記錄綁定到下拉列表框中
            foreach (DataRowView dr in ds.Tables[0].DefaultView)
            {
                cbxType.Items.Add(dr["name"].ToString());
            }
            cbxType.SelectedIndex = 0;
        }

        private void btn_Add_Click(object sender, EventArgs e)
        {
            CashContext cc = new CashContext();
            //根據用戶選項，查詢用戶選擇項的相關行
            DataRow dr = ((DataRow[])ds.Tables[0].Select("name='" + cbxType.SelectedItem.ToString() + "'"))[0];
            //聲明一個對象參數數組
            object[] args = null;
            //若有參數則將參數分割成字符串數組，用於實例化時所用的參數
            if (dr["para"].ToString() != "")
                args = dr["para"].ToString().Split(',');
           
            //通過反射實例化出相應的算法對象
            cc.setBehavior((CashSuper)Assembly.Load("Calculator").CreateInstance("Calculator." + dr["class"].ToString(), false, BindingFlags.Default, null, args, null, null));
            //cc.setBehavior(new CashNormal());

            double totalPrices = 0d;
            totalPrices = cc.GetResult(Convert.ToDouble(tb_Price.Text)*Convert.ToDouble(tb_Count.Text));
            total = total + totalPrices;
            lb_List.Items.Add("單價："+tb_Price.Text+" 數量："+tb_Count.Text+" "+cbxType.SelectedItem+" 合計"+totalPrices.ToString());
            lb_total.Text = total.ToString();
        }

    }
}

 

//計算模式類

namespace Calculator
{
    class CashContext
    {
        //聲明一個現金收費父類對象
        private CashSuper cs;

        public void setBehavior(CashSuper csuper)
        {
            this.cs = csuper;
        }

        public double GetResult(double money)
        {
            return cs.acceptCash(money);
        }
    }

    //現金收取父類
    abstract class CashSuper
    {
        //抽象方法：收取現金，參數爲原價，返回爲當前價
        public abstract double acceptCash(double money);
    }

    //正常收費，繼承CashSuper
    class CashNormal : CashSuper
    {
        public override double acceptCash(double money)
        {
            return money;
        }
    }

    //打折收費，繼承CashSuper
    class CashRebate : CashSuper
    {
        private double moneyRebate = 1d;

        public CashRebate(string moneyRebate)
        {
            this.moneyRebate = double.Parse(moneyRebate);
        }

        public override double acceptCash(double money)
        {
            return money * moneyRebate;
        }
    }

    //返利收費，CashSuper
    class CashReturn : CashSuper
    {
        private double moneyCondition = 0.0d;
        private double moneyReturn = 0.0d;
        //初始化時必須要輸入返利條件和返利值，比如慢300返100
        //則moneyCondition爲300，moneyReturn爲100
        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;
        }
    }

}

 

 

//XML數據

<?xml version="1.0" encoding="utf-8" ?>
<CashAcceptType>
  <type>
    <name>正常收費</name>
    <class>CashNormal</class>
    <para></para>
  </type>
  <type>
    <name>滿300返100</name>
    <class>CashReturn</class>
    <para>300,100</para>
  </type>
  <type>
    <name>滿200返50</name>
    <class>CashReturn</class>
    <para>200,50</para>
  </type>
  <type>
    <name>打8折</name>
    <class>CashRebate</class>
    <para>0.8</para>
  </type>
  <type>
    <name>打7折</name>
    <class>CashRebate</class>
    <para>0.7</para>
  </type>
</CashAcceptType>