①如果把所有的判斷邏輯和類的創(chuàng)建放在一個類中，那么出現(xiàn)的問題是，新增加一個功能，其他的功能也會收到影響。所以引進了簡單工廠模式，使得耦合性降低了。
②簡單工廠在添加新功能的時候，需要改工廠類，同樣違背開放-封閉原則，對更改是關(guān)閉的，對擴展是開放的。
③針對簡單工廠又出現(xiàn)了工廠方法，這時候?qū)⒐S類進一步抽象為多個工廠類。這時候我添加一個新功能，就需要添加一個新的工廠類和一個具體的功能類。工作量也變大了。

Product：抽象產(chǎn)品

ConcreteProduct：具體產(chǎn)品

Factory：抽象工廠

ConcreteFactory：具體工廠

3.代碼實現(xiàn)：

Weapon.cs

namespace FactoryMethod
{
    public class Weapon
    {
        //設(shè)計一個怪獸，血量是100(其實并不是很合適，怪獸應(yīng)該單獨設(shè)計
        //作為beat方法的參數(shù)傳入
        protected int monsterLife = 100;
        public virtual void beat()
        {

        }
    }
}

Knife.cs

namespace FactoryMethod
{
    public class Knife : Weapon
    {
        public override void beat()
        {
            while (monsterLife > 0)
            {
                base.monsterLife -= 20;
                Console.WriteLine("The Monster is still alive！");
            }
            Console.WriteLine("Excellent!The Monster is dead!"); 
        }
    }
}

Sword.cs

namespace FactoryMethod
{
   public class Sword:Weapon
    {
       public override void beat()
       {
           while (monsterLife > 0)
           {
               base.monsterLife -= 50;
               Console.WriteLine("The Monster is still alive！");
           }
           Console.WriteLine("Excellent!The Monster is dead!");
       }
    }
}

Stick.cs

namespace FactoryMethod
{
    public class Stick:Weapon
    {
        public override void beat()
        {
            while (monsterLife > 0)
            {
                base.monsterLife -= 100;
                Console.WriteLine("The Monster is still alive！");
            }
            Console.WriteLine("Excellent!The Monster is dead!");
        }
    }
}

IWeaponFactory.cs

namespace FactoryMethod
{
    public interface IWeaponFactory
    {
        Weapon CreateWeapon();
    }
}

KnifeFactory.cs

namespace FactoryMethod
{
   public class KnifeFactory:IWeaponFactory
    {
       public Weapon CreateWeapon()
       {
           return new Knife();
       }
    }
}

SwordFactory.cs

namespace FactoryMethod
{
    public class SwordFactory : IWeaponFactory
    {
        public Weapon CreateWeapon()
        {
            return new Sword();
        }
    }
}

StickFactory.cs

namespace FactoryMethod
{
    public class StickFactory:IWeaponFactory
    {
        public Weapon CreateWeapon()
        {
            return new Stick();
        }
    }
}

Program.cs

namespace FactoryMethod
{
    class Program
    {
        static void Main(string[] args)
        {
            IWeaponFactory factory = new SwordFactory();
            Weapon weapon = factory.CreateWeapon();
            weapon.beat();

            factory = new KnifeFactory();
            weapon = factory.CreateWeapon();
            weapon.beat();

            factory = new StickFactory();
            weapon = factory.CreateWeapon();
            weapon.beat();

            Console.ReadKey();

        }
    }
}

運行結(jié)果：