Question

我正在学习代表。我非常好奇地将代表应用于以下责任链模式。

请帮助我将代表申请到下一篇文章。

提前致谢。谢谢您的努力。

#region Chain of Responsibility Pattern
namespace Chain
{
    public class Player
    {
        public string Name { get; set; }
        public int Score { get; set; }
    }

    public abstract class PlayerHandler
    {
        protected PlayerHandler _Successor = null;

        public abstract void HandlePlayer(Player _player);

        public void SetupHandler(PlayerHandler _handler)
        {
            _Successor = _handler;
        }
    }

    public class Employee : PlayerHandler
    {
        public override void HandlePlayer(Player _player)
        {
            if (_player.Score <= 100)
            {
                MessageBox.Show(string.Format("{0} is greeted 
                                by Employee", _player.Name));
            }
            else
            {
                _Successor.HandlePlayer(_player);
            }
        }
    }

    public class Supervisor : PlayerHandler
    {
        public override void HandlePlayer(Player _player)
        {
            if (_player.Score >100 && _player.Score<=200)
            {
                MessageBox.Show(string.Format("{0} is greeted
                                by Supervisor", _player.Name));
            }
            else
            {
                _Successor.HandlePlayer(_player);
            }
        }
    }

    public class Manager : PlayerHandler
    {
        public override void HandlePlayer(Player _player)
        {
            if (_player.Score > 200)
            {
                MessageBox.Show(string.Format("{0} is
                                 greeted by Manager", _player.Name));
            }
            else
            {
                MessageBox.Show(string.Format("{0} got low score",
                                 _player.Name));
            }
        }
    }

}
#endregion

#region Main()

void Main()
{

        Chain.Player p1 = new Chain.Player();
        p1.Name = "Jon";
        p1.Score = 100;

        Chain.Player p2 = new Chain.Player();
        p2.Name = "William";
        p2.Score = 170;

        Chain.Player p3 = new Chain.Player();
        p3.Name = "Robert";
        p3.Score = 300;

        Chain.Employee emp = new Chain.Employee();
        Chain.Manager mgr = new Chain.Manager();
        Chain.Supervisor sup = new Chain.Supervisor();
        emp.SetupHandler(sup);
        sup.SetupHandler(mgr);

        emp.HandlePlayer(p1);
        emp.HandlePlayer(p2);
        emp.HandlePlayer(p3);  

}

#endregion

Answer 1

考虑以下示例：

public class Player
{
    private readonly string _name;
    private readonly string _surname;
    private readonly int _score;
    private string _nickName = "";


    public Player(string name, string surname, int score)
    {
        _name = name;
        _surname = surname;
        _score = score;
    }

    public string FullName
    {
        get
        {
            if (string.IsNullOrEmpty(_nickName)) return string.Format("{0} {1}", _name, _surname);
            else return string.Format("{0} \"{1}\" {2}", _name, _nickName, _surname);
        }
    }

    public int Score
    {
        get { return _score; }
    }


    public string NickName
    {
        get { return _nickName; }
        set { _nickName = value; }
    }
}

public delegate bool PlayerHandlerDelegate(Player player);

public class HandlersChain
{
    private readonly List<PlayerHandlerDelegate> _chain = new List<PlayerHandlerDelegate>();

    public void AddHandler(PlayerHandlerDelegate handler)
    {
        _chain.Add(handler);
    }

    public void HandlePlayer(Player player)
    {
        foreach (PlayerHandlerDelegate handler in _chain)
        {
            if (handler(player)) break;
        }
    }
}




class Program
{
    static PlayerHandlerDelegate CreateHandlerDelegate(string position, int minScore)
    {
        return delegate(Player p)
                {
                    if (p.Score > minScore)
                    {
                        //MessageBox.Show(string.Format("{0} is greeted by {1}", p.FullName, position));
                        Console.WriteLine(string.Format("{0} is greeted by {1}", p.FullName, position));
                        return true;
                    }
                    return false;
                };
    }

    static void Main(string[] args)
    {
        Player p1 = new Player("John", "Smith", 100);
        Player p2 = new Player("William", "Brown", 170);
        Player p3 = new Player("Robert", "Johns", 500);

        HandlersChain chain = new HandlersChain();
        chain.AddHandler(delegate(Player p)
                            {
                                if (p.Score > 400)
                                {
                                    p.NickName = "The Hero";
                                }
                                return false;
                            });
        chain.AddHandler(CreateHandlerDelegate("Manager", 300));
        chain.AddHandler(CreateHandlerDelegate("Supervisor", 200));
        chain.AddHandler(CreateHandlerDelegate("Employee", 100));

        chain.AddHandler(delegate(Player p)
            {
                if (p.Score <= 100)
                {
                    //MessageBox.Show(string.Format("{0} got low score", p.FullName));
                    Console.WriteLine(string.Format("{0} got low score", p.FullName));
                    return true;
                }
                return false;
            });


        chain.HandlePlayer(p1);
        chain.HandlePlayer(p2);
        chain.HandlePlayer(p3);
    }
}

我使用了Console应用程序，因此MessageBox更改为Console。

这里的原始设计略有改变。现在有一个包含处理程序集合的链对象。处理程序彼此不了解。 Chain按添加顺序调用它们。如果玩家被“完全处理”，即如果不应该调用链中的其他处理程序，则每个处理程序返回true。从理论上讲，如果处理程序做了一些工作，则不需要处理程序返回true（即停止处理）。这取决于潜在的逻辑。您还可以看到所有“典型”委托都是通过使用闭包的特殊方法创建的（请参阅http://en.wikipedia.org/wiki/Closure_(computer_science)，遗憾的是链接“（”如果添加为链接似乎会被破坏）。

P.S。我还在使用VS 2005，所以在我的样本中没有像lambda这样的时髦东西。遗憾。

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1 个答案: