目錄

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基本概念

代碼及實例

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基本概念

工廠方法模式（Factory Method）：定義一個用于創建對象的接口，讓字類決定實例化哪一個類。工廠方法使一個類的實例化延遲到其子類；

簡單工廠模式的最大優點在用戶工廠類中包含了必要的邏輯判斷，根據客戶端的選擇條件動態實例化相關的類，對于客戶端來說，去除了具體產品的依賴。

工廠方法模式實現時，客戶端需要決定實例化哪一個工廠來實現運算類，選擇判斷的問題還是存在的，也就是說，工廠方法把簡單工廠內部邏輯判斷移到了客戶端代碼來進行。

UML圖如下（這里以計算器為例）

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代碼及實例

程序運行截圖如下：

源碼如下：

Head.h

#ifndef HEAD_H #define HEAD_H//運算相關 class Operation{public:double m_numberA;double m_numberB;virtual double getResult(); };class AddOperation: public Operation{public:AddOperation();double getResult(); };class MultiOperation: public Operation{public:MultiOperation();double getResult(); };//工廠相關class IFactory{public:virtual Operation *createOperation(); };class AddFactory: public IFactory{public:Operation *createOperation(); };class MultiFactory: public IFactory{public:Operation *createOperation(); };#endif //HEAD_H

Head.cpp

#include "Head.h" #include <iostream> #include <string> using namespace std;Operation *IFactory::createOperation() {return nullptr; }Operation *AddFactory::createOperation() {return new AddOperation; }double Operation::getResult() {return -1; }AddOperation::AddOperation() {m_numberA = 0.0;m_numberB = 0.0; }double AddOperation::getResult() {return m_numberA + m_numberB; }MultiOperation::MultiOperation() {m_numberA = 0.0;m_numberB = 0.0; }double MultiOperation::getResult() {return m_numberA * m_numberB; }Operation * MultiFactory::createOperation() {return new MultiOperation; }

main.cpp

#include "Head.h" #include <iostream> using namespace std;int main(int *argc, int *argv){IFactory *operAddFactory = new AddFactory;Operation *addOper = operAddFactory->createOperation();addOper->m_numberA = 100;addOper->m_numberB = 200;cout << "operAddFactory result is : " << addOper->getResult() << endl;delete operAddFactory;delete addOper;cout << "--------------- 華麗的分割線 ---------------" << endl;IFactory *operMultiFactory = new MultiFactory;Operation *multiOper = operMultiFactory->createOperation();multiOper->m_numberA = 12;multiOper->m_numberB = 5;cout << "operMultiFactory result is : " << multiOper->getResult() << endl;delete operMultiFactory;delete multiOper;getchar();return 0; }

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