簡述

簡單工廠模式的核心在于使用一個工廠類根據(jù)需求動態(tài)生成子類對象歇由。以計算器程序作為例子，加減乘除都分別作為運(yùn)算類的子類果港，然后讓工廠類根據(jù)要求動態(tài)實(shí)例化子類沦泌。

圖示

簡單工廠模式圖示

代碼實(shí)現(xiàn)

/////////////////////////////
//
// @ FileName : Operation.h
// @ Date : 2018-08-06 18:04
//
/////////////////////////////

#pragma once

#include <cstdio>
#include <iostream>
#include <windows.h>

class Operation
{
private:
    double _numberA;
    double _numberB;
public:
    Operation() :_numberA(0), _numberB(0) {}
    void setNumberA(double&);
    void setNumberB(double&);
    double getNumberA() const;
    double getNumberB() const;
    double virtual getResult()
    {
        return 0;
    }
};

void Operation::setNumberA(double& numberA)
{
    this->_numberA = numberA;
    return;
}

void Operation::setNumberB(double& numberB)
{
    this->_numberB = numberB;
    return;
}

double Operation::getNumberA() const
{
    return this->_numberA;
}

double Operation::getNumberB() const
{
    return this->_numberB;
}

class OperationAdd : public Operation
{
    double getResult()
    {
        return getNumberA() + getNumberB();
    }
};

class OperationSub : public Operation
{
    double getResult()
    {
        return getNumberA() - getNumberB();
    }
};

class OperationMul : public Operation
{
    double getResult()
    {
        return getNumberA() * getNumberB();
    }
};

class OperationDiv : public Operation
{
    double getResult()
    {
        if (getNumberB() > 0.0)
        {
            return getNumberA() / getNumberB();
        }
        else
        {
            MessageBox(NULL, "Div Args-2 Should Be Bigger than Zero!", "Error", MB_OK);
            ExitProcess(0);
        }
    }
};

class OperaionFactory
{
public:
    static Operation* createOperate(char&);
};

Operation* OperaionFactory::createOperate(char& operate)
{
    Operation *oper = NULL;
    switch (operate)
    {
    case '+':
        oper = new OperationAdd();
        break;
    case '-':
        oper = new OperationSub();
        break;
    case '*':
        oper = new OperationMul();
        break;
    case '/':
        oper = new OperationDiv();
        break;
    default:
        MessageBox(NULL, "Symbol Error!", "Error", MB_OK);
        ExitProcess(0);
    }
    return oper;
}

/////////////////////////////
//
// @ FileName : SFM.cpp
// @ Date : 2018-08-06 18:04
//
/////////////////////////////

#include "Operation.h"

using namespace std;

int main(void)
{
    Operation *oper;
    double _numberA = 0;
    double _numberB = 0;
    char symbol = '\0';
    scanf("%lf %c %lf", &_numberA, &symbol, &_numberB);
    oper = OperaionFactory::createOperate(symbol);
    oper->setNumberA(_numberA);
    oper->setNumberB(_numberB);
    double result = oper->getResult();
    cout << result << endl;
    system("pause");
    return 0;
}