介紹
相較於簡單工廠模式，工廠方法模式將工廠端抽象化，讓實作該工廠的子工廠處理要創建的產品。可想像為原工廠的產線可生產玩具、文具、廚具，工廠方法模式將該工廠產線依產品種類獨立拉出來，A產線只產玩具，B產線只產文具，C產線只產廚具。

C++範例

#include <iostream>

class Monster
{
public:
    virtual void Say() const = 0;
    virtual ~Monster() {}
};

// 實作怪物介面1
class HeadcrabMonster : public Monster
{
public:
    void Say() const override
    {
        std::cout << "I am a headcrab!" << std::endl;
    }
};

// 實作怪物介面2
class ZombieMonster : public Monster
{
public:
    void Say() const override
    {
        std::cout << "I am a zombie!" << std::endl;
    }
};

// 現在工廠變成介面
class MonsterFactory
{
public:
    virtual Monster *CreateMonster() = 0;
    virtual ~MonsterFactory() {}
};

// 專產怪物1的工廠
class HeadcrabFactory : public MonsterFactory
{
public:
    Monster *CreateMonster()
    {
        return new HeadcrabMonster();
    }
};

// 專產怪物2的工廠
class ZombieFactory : public MonsterFactory
{
public:
    Monster *CreateMonster()
    {
        return new ZombieMonster();
    }
};

int main()
{
    // 建立專產怪物A的工廠
    HeadcrabFactory *headcrabFactory = new HeadcrabFactory();
    // 用工廠創建怪物A
    Monster *headcrab = headcrabFactory->CreateMonster();
    headcrab->Say();

    delete headcrab;
    delete headcrabFactory;

    // 建立專產怪物B的工廠
    ZombieFactory *zombieFactory = new ZombieFactory();
    // 用工廠創建怪物B
    Monster *zombie = zombieFactory->CreateMonster();
    zombie->Say();

    delete zombie;
    delete zombieFactory;

    return 0;
}

Output:

I am a headcrab!
I am a zombie!