時間過得好快，不知不覺又到了寫部落格的time了；這次簡單介紹一些簡單工廠、策略模式，還有他們的區別和聯絡，恩，進入正題：

抽象理論藉助具體例項更有助於理解，這次藉助我們熟知的“商場促銷”，效果圖：      

兩個模式相同的程式碼部分： 

 //客戶端
        double total=0.0d;
        private void Form1_Load(object sender, EventArgs e)
        {
            cmdCount.Items.AddRange(new object[] { "正常收費", "打八折", "打七折", "打五折" });

            cmdCount.SelectedIndex = 0;
        }
        //現金收費抽象類
        abstract class CashSuper
        {
            //現金收取父類的抽象方法，收取現金，引數為原價，返回為當前價
            public abstract double acceptCash(double money);
        }
        //正常收費類
        class CashNormal:CashSuper
        {
            public override double acceptCash(double money)
            {
                //正常收取，原價返回
                return money;
            }
        }
        //打折收費子類
        class CashRebate:CashSuper
        {
            private double moneyRebate = 1d;
            public CashRebate (string moneyRebate)
            {
                //打折收費，初始化時輸入折扣率：如0.8
                this.moneyRebate = double.Parse(moneyRebate);
            }
            //重寫方法
            public override double acceptCash(double money)
            {
                //現金*折扣率
                return money * moneyRebate;
            }
        }
        //返利收費
        class CashReturn:CashSuper
        {
            private double moneyCondition = 0.0d;
            private double moneyReturn = 0.0d;
            //返利收費，初始化輸入返利條件,返利值
            public CashReturn (string moneyCondition,string moneyReturn)
            {
                //條件、返利值
                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;
            }
        }
 

   CashSuper、CashNormal、CashRebate、CahReturn是具體的子類，他們裡面的acceptCash方法是對CashSuper.acceptCash這一虛方法的重寫，使其變成帶有各自Signet的方法 。               

   class CashFactory
        {
            //現金收取工廠
            //不同的情況，可增加分支
            public static CashSuper createCashAccept(string type)
            {
                CashSuper cs = null;
                switch (type)
                {
                    case"正常收費":
                        cs = new CashNormal();
                        break;
                    case "滿300返100":
                        CashReturn cr1=new CashReturn ("300","100");
                        cs=cr1 ;
                        break ;
                    case"打八折":
                        CashRebate cr2 = new CashRebate("0.8");
                        cs = cr2;
                        break;
                }
                return cs;
            }
        }
        private void btnSure_Click(object sender, EventArgs e)
        {
            //簡單工廠模式，根據下拉列表框生成相應的物件
            CashSuper csuper = CashFactory.createCashAccept(cmdCount.SelectedItem.ToString());
            double totalPrices = 0d;
            //csuper自帶物件，用相應的acceptCash方法計算
            totalPrices = csuper.acceptCash(Convert.ToDouble(txtprice.Text)
                * Convert.ToDouble(txtNum.Text));

            total = total + totalPrices;
            //顯示在listbox中
            lstSum.Items.Add("單價：" + txtprice.Text + "數量" + txtNum.Text + ""
                + cmdCount.SelectedItem + "合計" + totalPrices.ToString());
           //顯示總計
            lblSum.Text = total.ToString();
        }
 

     違反了“開閉原則”：由於工廠類集中了所有例項的建立邏輯，違反了高內聚責任分配原則（GRASP職責分配原則），將全部建立邏輯集中到了一個工廠類中;它所能建立的類只能是事先考慮到的，如果需要新增新的類，則就需要改變工廠類，很難避免模組功能的蔓延，對系統的維護和擴充套件非常不利。

策略模式

<span style="font-family:KaiTi_GB2312;font-size:18px;">  private void btnSure_Click(object sender, EventArgs e)</span><span style="font-family: Arial; font-size: 14px;">
        {
            CashContext cc = null;
            //下拉列表，相應策略、傳人
            switch (cmdCount .SelectedItem.ToString ())
            {
                case"正常收費":
                    //相應的方法
                    cc = new CashContext(new CashNormal());
                    break;
                case "滿300返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(txtNum.Text) * Convert.ToDouble(txtprice.Text));

            total = total + totalPrices;
            lstSum.Items.Add("單價" + txtprice.Text + "數量" + txtNum.Text
                + " " + cmdCount.SelectedItem + "合計：" + total.ToString());
            lblSum.Text = total.ToString();
        }
        class CashContext
        {
            //宣告一個cashsuper物件
            private CashSuper cs;
            //傳入具體收費策略
            public CashContext (CashSuper csuper)
            {
                this.cs = csuper;
            }
            //根據策略、運用方法、計算結果
            public double GetResult(double money)
            {
                return cs.acceptCash(money);
            }
        }
</span>

簡單工廠和策略模式的結合

      private void btnSure_Click(object sender, EventArgs e)
        {
            //將相應的演算法字串傳人cashcontext物件中
            CashContext csuper = new CashContext(cmdCount.SelectedItem.ToString());
            double totalPrices = 0d;
            //計算總價
            totalPrices = csuper.GetResult(Convert.ToDouble(txtNum.Text) * Convert.ToDouble(txtprice.Text));
            total = total + totalPrices;
            //顯示
            lstSum.Items.Add("單價" + txtprice.Text + "數量" + txtNum.Text
                + " " + cmdCount.SelectedItem + "合計：" + total.ToString());
            lblSum.Text = total.ToString();
        }

        class CashContext
        {
            //宣告一個cashsuper物件
             CashSuper cs=null;
            //傳入具體收費策略
            public CashContext (string type)
            {
                switch (type)
                {
                    case"正常收費":
                      CashNormal   cs0 = new CashNormal();
                        cs=cs0;
                        break;
                    case "滿300返100":
                        CashReturn cr1=new CashReturn ("300","100");
                        cs=cr1 ;
                        break ;
                    case"打八折":
                        CashRebate cr2 = new CashRebate("0.8");
                        cs = cr2;
                        break;
                }
            }
            //根據策略、運用方法、計算結果
            public double GetResult(double money)
            {
                return cs.acceptCash(money);
            }
        }

http://blog.csdn.net/hguisu/article/details/7558249  最後的例子亮了

thanks for your time