策略模式是一種定義一系列演算法的方法，從概念上來看，所有這些演算法完成的都是相同的工作，只是實現不同，它可以以相同的方式呼叫所有的演算法，減少了各種演算法類與使用演算法類之間的耦合。

   策略模式（Strategy）：它定義了演算法家族，分別封裝起來，讓它們之間可以互相替換，此模式讓演算法的變化，不會影響到使用演算法的客戶。

   當不同的行為堆砌在一個類中時，就很難避免使用條件語句來選擇合適的行為。將這些行為封裝在一個個獨立的Strategy類中，可以在使用這些行為的類中消除條件語句。

    程式碼寫完之後，感覺它與簡單工廠模式區別不是很大，就是讓使用者只需要認識context一個類就行了，簡單工廠的話多認識一個cashsuper類。

     下面分別列舉簡單工廠，策略模式，策略模式結合簡單工廠實現的程式碼（不知道如何上傳整個原始碼）

簡單工廠模式

CashSuperMarket類 CashNormal類 CashRebate類 CashReturn類繼承於CashSuperMarket類 class CashSuperMarket { //抽象方法：收取現金，引數為原價，返回為當前價 public: virtual double acceptCash(double money) { return 0.0; }; int GetPoint(double money, double moneyCondition, int pointReturn) { int point; int x = (money / moneyCondition); if(money >= moneyCondition) point = x*pointReturn; return point; } }; CashNormal類 #include "CashSuperMarket.h" class CashNormal :public CashSuperMarket { public: CashNormal(void) { } public: ~CashNormal(void) { } public: double acceptCash(double money) { return money; } }; CashRebate類 #include "CashSuperMarket.h" //打折收費 class CashRebate : public CashSuperMarket { public: CashRebate(void) { } public: ~CashRebate(void) { } private: double moneyRebate; //初始化時，必需要輸入折扣率,如八折，就是0.8 public://建構函式 CashRebate(double rebate) { this->moneyRebate = rebate; } public: double acceptCash(double money) { return money * moneyRebate; } }; CashReturn類 #include "CashSuperMarket.h" //返利收費 class CashReturn : public CashSuperMarket { public: CashReturn(void) { } public: ~CashReturn(void) { } private: double moneyCondition ; double moneyReturn ; //初始化時必須要輸入返利條件和返利值，比如滿300返100，則moneyCondition為300，moneyReturn為100 public: CashReturn(double moneyCondition, double moneyReturn) { this->moneyCondition = moneyCondition; this->moneyReturn = moneyReturn; } public: double acceptCash(double money) { double result = money; //若大於返利條件，則需要減去返利值 int x = (money / moneyCondition); if (money >= moneyCondition) result = money - x * moneyReturn; return result; } }; 收費物件生成的工廠 #include "CashSuperMarket.h" #include "CashNormal.h" #include "CashRebate.h" #include "CashReturn.h" //#include "GetPoint.h" #include <iostream> using namespace std; class CashFactory { //根據條件返回相應的物件 public: static CashSuperMarket* createCashAccept(int type) { //CashSuperMarket cs = NULL; CashSuperMarket* cs; switch(type) { //case "正常收費": case 2: { cs = new CashNormal(); break; } case 1://case "滿300返100": { CashReturn* cr1 = new CashReturn(300, 100); cs = cr1; break; } case 0://case "打8折": { CashRebate* cr2 = new CashRebate(0.8); cs = cr2; break; } /*case 0: { GetPoint* cr3 = new GetPoint(100, 10); cs = cr3; break; }*/ } return cs; } }; 客戶端的主要響應函式 void C工廠模式Dlg::OnBnClickedOk() { // TODO: 在此新增控制元件通知處理程式程式碼 UpdateData(true); int type = m_pComboBox.GetCurSel(); CString message; m_pComboBox.GetLBText(type, message); double money = m_price*m_num; CashSuperMarket* cashSuper = CashFactory::createCashAccept(type); totalPrice = cashSuper->acceptCash(money); total += totalPrice; int point = cashSuper->GetPoint(total, 100, 10); m_detail.Format("單價:%f 數量:%d折扣:%s本次積分：%d/n合計：%f", m_price, m_num, message , point, total); CString statictotalPrice; statictotalPrice.Format("%f", total); CStatic* price = (CStatic*)GetDlgItem(IDC_TOTALPRICE); price->SetWindowText(statictotalPrice); UpdateData(false); } void C工廠模式Dlg::OnBnClickedReset() { // TODO: 在此新增控制元件通知處理程式程式碼 m_price = 0; m_num = 0; total = 0; m_detail = _T(""); CStatic* price = (CStatic*)GetDlgItem(IDC_TOTALPRICE); price->SetWindowText("0"); UpdateData(false); }

策略模式

CashNormal類、CashRebate類、 CashReturn類、 CashSuperMarket類保持不變，需要修改的是去掉工廠類，將選擇收款方式轉移到客戶端，新增一個CashContext類

CashContext類 #include "CashSuperMarket.h" class CashContext { public: CashContext(void) { } public: ~CashContext(void) { } private: CashSuperMarket* cs; public: CashContext(CashSuperMarket* csupermarket) { this->cs = csupermarket; } public: double GetResult(double money) { return cs->acceptCash(money); } }; 客戶端實現 void C策略模式Dlg::OnBnClickedOk() { // TODO: 在此新增控制元件通知處理程式程式碼 UpdateData(true); int type = m_pComboBox.GetCurSel(); CString message; m_pComboBox.GetLBText(type, message); double money = m_price*m_num; CashContext* cc; switch(type) { //case "正常收費": case 2: { cc = new CashContext(new CashNormal()); break; } case 1://case "滿300返100": { cc = new CashContext(new CashReturn(300, 100)); break; } case 0://case "打8折": { cc = new CashContext(new CashRebate(0.8)); break; } } //totalPrice = cashSuper->acceptCash(money); totalPrice = cc->GetResult(money); total += totalPrice; //int point = cashSuper->GetPoint(total, 100, 10); /*m_detail.Format("單價:%f 數量:%d折扣:%s本次積分：%d/n合計：%f", m_price, m_num, message , point, total);*/ m_detail.Format("單價:%f 數量:%d折扣:%s合計：%f", m_price, m_num, message , total); CString statictotalPrice; statictotalPrice.Format("%f", total); CStatic* price = (CStatic*)GetDlgItem(IDC_TOTALPRICE); price->SetWindowText(statictotalPrice); UpdateData(false); }

 策略模式與工廠模式結合 只需修改CashContext類和客戶端的實現部分

CashContext類 #include "CashSuperMarket.h" #include "CashNormal.h" #include "CashRebate.h" #include "CashReturn.h" class CashContext { public: CashContext(void) { } public: ~CashContext(void) { } private: CashSuperMarket* cs; public: CashContext(int type) { switch(type) { //case "正常收費": case 2: { cs = new CashNormal(); break; } case 1://case "滿300返100": { cs = new CashReturn(300, 100); break; } case 0://case "打8折": { cs = new CashRebate(0.8); break; } } } /*CashContext(CashSuperMarket* csupermarket) { this->cs = csupermarket; }*/ public: double GetResult(double money) { return cs->acceptCash(money); } }; 客戶端實現 void C策略模式&工廠模式Dlg::OnBnClickedOk() { // TODO: 在此新增控制元件通知處理程式程式碼 UpdateData(true); int type = m_pComboBox.GetCurSel(); CString message; m_pComboBox.GetLBText(type, message); double money = m_price*m_num; CashContext* cc = new CashContext(type); totalPrice = cc->GetResult(money); total += totalPrice; m_detail.Format("單價:%f 數量:%d折扣:%s合計：%f", m_price, m_num, message , total); CString statictotalPrice; statictotalPrice.Format("%f", total); CStatic* price = (CStatic*)GetDlgItem(IDC_TOTALPRICE); price->SetWindowText(statictotalPrice); UpdateData(false); }

這一章早就該發了，結果因為一些事情拖到今天，呵呵