设计模式复习-工厂方法模式

设计模式复习-工厂方法模式

设计模式复习-工厂方法模式

相对于简单工厂，工厂方法是把算法类的实例化延迟到了调用者那去做，调用者根据自己的需要，自己实例化相关的工厂并且生产相关算法。这么做是因为简单工厂是不满足OCP的，因为如果想添加新的算法，就得去改工厂函数里面的那个switch，这样容易在增加新的功能时引入新问题，而工厂方法不会导致这个问题，在算法扩充的时候满足OCP，不需要改之前原有的东西，直接往上加就行了。

//FactoryMode.h#pragma once//抽象算法接口class CinterfaceAlgorithm {public:virtual bool GetValue(const int &nNumberA, const int &nNumberB, int &nNumberAns) = 0;};class CAddition : public CinterfaceAlgorithm {public:bool GetValue(const int &nNumberA, const int &nNumberB, int &nNumberAns) {nNumberAns = nNumberA + nNumberB;return true;}};class CSubtraction : public CinterfaceAlgorithm {public:bool GetValue(const int &nNumberA, const int &nNumberB, int &nNumberAns) {nNumberAns = nNumberA - nNumberB;return true;}};class CMultiplication : public CinterfaceAlgorithm {public:bool GetValue(const int &nNumberA, const int &nNumberB, int &nNumberAns) {nNumberAns = nNumberA * nNumberB;return true;}};class CDivision : public CinterfaceAlgorithm {public:bool GetValue(const int &nNumberA, const int &nNumberB, int &nNumberAns) {if (nNumberB == 0) {return false;}nNumberAns = nNumberA / nNumberB;return true;}};//工厂接口class CinterfaceFactory {public:virtual CinterfaceAlgorithm * GetFactoryBody() = 0;};class CAdditionFactory : public CinterfaceFactory {CinterfaceAlgorithm * GetFactoryBody(){return new CAddition();}};class CSubtractionFactory : public CinterfaceFactory {CinterfaceAlgorithm * GetFactoryBody() {return new CSubtraction();}};class CMultiplicationFactory : public CinterfaceFactory {CinterfaceAlgorithm * GetFactoryBody() {return new CMultiplication();}};class CDivisionFactory : public CinterfaceFactory {CinterfaceAlgorithm * GetFactoryBody() {return new CDivision();}};#include "stdafx.h"#include "FactoryMode.h"#include using namespace std;int main() {CinterfaceAlgorithm *pHashMemoryAlgorithm[10] = { 0 };CinterfaceFactory * pHashMemoryFactory[10] = { 0 };int nAlgorithmId = -1, nFactoryId = -1, nAns = 0;pHashMemoryFactory[++nFactoryId] = new CAdditionFactory();pHashMemoryAlgorithm[++nAlgorithmId] = pHashMemoryFactory[nFactoryId]->GetFactoryBody();pHashMemoryFactory[++nFactoryId] = new CSubtractionFactory();pHashMemoryAlgorithm[++nAlgorithmId] = pHashMemoryFactory[nFactoryId]->GetFactoryBody();pHashMemoryFactory[++nFactoryId] = new CMultiplicationFactory();pHashMemoryAlgorithm[++nAlgorithmId] = pHashMemoryFactory[nFactoryId]->GetFactoryBody();pHashMemoryFactory[++nFactoryId] = new CDivisionFactory();pHashMemoryAlgorithm[++nAlgorithmId] = pHashMemoryFactory[nFactoryId]->GetFactoryBody();for (int nPoit = 0; nPoit <= nAlgorithmId; nPoit++) {if (pHashMemoryAlgorithm[nPoit] != NULL && pHashMemoryAlgorithm[nPoit]->GetValue(1, 5, nAns)) {cout << nAns << endl;}else {cout << "Error" << endl;}}for (int nPoit = 0; nPoit <= nAlgorithmId; nPoit++) {delete pHashMemoryAlgorithm[nPoit];delete pHashMemoryFactory[nPoit];}//getchar();return 0;}

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