簡介

在之前蛋褥，筆者曾簡單介紹過簡單工廠模式吮成，我們說過簡單工廠模式可以使用工廠類根據(jù)需求動(dòng)態(tài)生成子類對(duì)象频丘，從而方便了未來對(duì)算法進(jìn)行維護(hù)和擴(kuò)展蓝仲。而工廠模式相較之于簡單工廠模式更為復(fù)雜俱病，工廠模式對(duì)工廠類進(jìn)行了詳細(xì)的子類化，為每一個(gè)算法都建立了獨(dú)立的工廠杂曲，這樣的優(yōu)點(diǎn)在于可以在算法擴(kuò)展的時(shí)候避免修改總工廠類庶艾，而只要生成相應(yīng)的子類就可以了，盡可能避免了違背“開閉原則”的情況擎勘，但缺點(diǎn)在于這樣switch一類的條件判斷就必須從原來的工廠類搬到了客戶端咱揍。下面我們通過一個(gè)和當(dāng)時(shí)在簡單工廠模式章節(jié)一樣的計(jì)算器算法的例子實(shí)現(xiàn)一下工廠模式。

圖示

工廠模式圖示

代碼實(shí)現(xiàn)

////////////////////////////
//
//  @Author : PeterZheng
//  @FileName : FactoryModeDefine.h
//  @Date : 2018-08-13 19:17
//
////////////////////////////

#pragma once
#ifndef FMDINCLUDE
#define FMDINCLUDE

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

#endif

//運(yùn)算符操作類
class Operation
{
public:
    double _numberA = 0;
    double _numberB = 0;
    double result = 0;
    virtual double GetResult() { return 0.0; };
};

//總工廠類
class IFactory
{
public:
    virtual Operation* CreateFactory() = 0;
};

//加法操作類
class AddOperation : public Operation
{
    virtual double GetResult()
    {
        return _numberA + _numberB;
    }
};

//減法操作類
class SubOperation : public Operation
{
    virtual double GetResult()
    {
        return _numberA - _numberB;
    }
};

//乘法操作類
class MulOperation : public Operation
{
    virtual double GetResult()
    {
        return _numberA * _numberB;
    }
};

//除法操作類
class DivOperation : public Operation
{
    virtual double GetResult()
    {
        if (_numberB != 0)
            return _numberA / _numberB;
        else
            ExitProcess(0);
    }
};

//加法工廠類
class AddOpFactory : public IFactory
{
    virtual Operation* CreateFactory()
    {
        return new AddOperation();
    }
};

//減法工廠類
class SubOpFactory : public IFactory
{
    virtual Operation* CreateFactory()
    {
        return new SubOperation();
    }
};

//乘法工廠類
class MulOpFactory : public IFactory
{
    virtual Operation* CreateFactory()
    {
        return new MulOperation();
    }
};

//除法工廠類
class DivOpFactory : public IFactory
{
    virtual Operation* CreateFactory()
    {
        return new DivOperation();
    }
};

////////////////////////////
//
//  @Author : PeterZheng
//  @FileName : FMDemo.cpp
//  @Date : 2018-08-13 19:50
//
////////////////////////////

#include "FactoryModeDefine.h"

int main(void)
{
    double _numberA = 0;
    double _numberB = 0;
    char symbol = '\0';
    Operation *op = NULL;
    IFactory *ft = NULL;
    scanf("%lf %c %lf", &_numberA, &symbol, &_numberB);
    switch (symbol)
    {
    case '+':
        ft = new AddOpFactory();
        break;
    case '-':
        ft = new SubOpFactory();
        break;
    case '*':
        ft = new MulOpFactory();
        break;
    case '/':
        ft = new DivOpFactory();
        break;
    default:
        ExitProcess(0);
    }
    op = ft->CreateFactory();
    op->_numberA = _numberA;
    op->_numberB = _numberB;
    op->result = op->GetResult();
    std::cout << op->result << std::endl;
    system("pause");
    return 0;
}