责任链模式 方法链

责任链模式（Chain of Responsibility Pattern）

情景：假设一个卡牌类游戏，怪物卡和属性卡 可以给怪物增加攻击属性，防御属性

    /// <summary>
    /// 生物基础
    /// </summary>
    public class Creature
    {
        public string Name;
        public int Attack, Defense;

        public Creature(string name, int attack, int defense)
        {
            Name = name;
            Attack = attack;
            Defense = defense;
        }
        public override string ToString()
        {
            return $"Name:{Name},Attack:{Attack},Defense:{Defense}";
        }
    }

创建一个责任链头：

    /// <summary>
    /// 装备卡
    /// </summary>
    public class CreatureModifer
    {
        protected Creature creature;
        protected CreatureModifer next;
        public CreatureModifer(Creature creature)
        {
            this.creature = creature;
        }
        public void Add(CreatureModifer cm)
        {
            if (next != null) next.Add(cm);
            else next = cm;
        }
        public virtual void Handle() => next?.Handle(); 
    }

双倍攻击：

 /// <summary>
    /// 双重攻击Buff
    /// </summary>
    public class DoubleAttackBuff : CreatureModifer
    {
        public DoubleAttackBuff(Creature creature) : base(creature)
        {
        }
        public override void Handle()
        {
            Console.WriteLine("获取Buff，双倍攻击！");
            creature.Attack *= 2;
            base.Handle();
        }
    }

增加防御：

public class IncreaseProtectionBuff : CreatureModifer
    {
        public IncreaseProtectionBuff(Creature creature) : base(creature)
        {
        }
        public override void Handle()
        {
            Console.WriteLine("获取Buff，防御+5！");
            creature.Defense += 5;
            base.Handle();
        }
    }

禁止BUFF：

    public class BuufProhibition : CreatureModifer
    {
        public BuufProhibition(Creature creature) : base(creature)
        {
        }
        public override void Handle()
        {
            //base.Handle();
        }
    }

开始使用：

var Goblin = new Creature("Goblin", 2, 2);//创建一个哥布林
            Console.WriteLine(Goblin);

            var buff = new CreatureModifer(Goblin);//创建一个责任链头

            //buff.Add(new BuufProhibition(Goblin));//Buff无效

            buff.Add(new DoubleAttackBuff(Goblin));//增加双倍攻击
            buff.Add(new IncreaseProtectionBuff(Goblin));//增加防御力
            buff.Handle();//Buff生效
            Console.WriteLine(Goblin);

　　来看结果：