設計模式（22）---備忘錄模式

2019-11-14 16:14:52

字體：大中小

來源：轉載

供稿：網友

基本定義

備忘錄模式：在不破壞封裝性的前提下，捕獲一個對象的內部狀態，并在該對象之外保存這個狀態。這樣以后就可以將該對象恢復到原先保存的狀態。

解釋：簡單來說，就是保存一個對象在某一時刻的特定狀態，在以后需要的時候可以將對象恢復到保存時的狀態。

基本代碼：

class Originator    {        PRivate string state;        public string State        {            get { return state; }            set { state = value; }        }        public Memento CreateMemento()        {            return new Memento(state);        }        public void SetMemento(Memento memento)        {            state = memento.State;        }        public void Display()        {            Console.WriteLine("State=" + state);        }    }    class Memento    {        private string state;        public string State        {            get { return state; }        }        public Memento(string state)        {            this.state = state;        }    }    class Caretaker    {        private Memento memento1;        public Memento Memento1        {            get { return memento1; }            set { memento1 = value; }        }    }

class Originator    {        private string state;        public string State        {            get { return state; }            set { state = value; }        }        public Memento CreateMemento()        {            return new Memento(state);        }        public void SetMemento(Memento memento)        {            state = memento.State;        }        public void Display()        {            Console.WriteLine("State=" + state);        }    }    class Memento    {        private string state;        public string State        {            get { return state; }        }        public Memento(string state)        {            this.state = state;        }    }    class Caretaker    {        private Memento memento1;        public Memento Memento1        {            get { return memento1; }            set { memento1 = value; }        }    }

客戶端調用：

Originator originator = new Originator();            originator.State = "on";            originator.Display();            Caretaker caretaker = new Caretaker();            caretaker.Memento1 = originator.CreateMemento();            originator.State = "off";            originator.Display();            originator.SetMemento(caretaker.Memento1);            originator.Display();

View Code

列舉具體實例：

打游戲，保存一角色在打boss前的狀態，待打boss結束后再恢復到它之前的狀態。

class Program    {        static void Main(string[] args)        {            Role role = new Role(100, 100);            Console.WriteLine("大戰前：");            role.Display();            Caretaker caretaker = new Caretaker();            caretaker.memento = role.SaveMemento();            role.SetBloodFlow(20);            role.SetMagicPoint(20);            Console.WriteLine("大戰");            role.Display();            role.RestoreMemento(caretaker.GetMemento());            Console.WriteLine("恢復");            role.Display();            Console.Read();        }    }    class Role    {        private int bloodFlow;        private int magicPoint;        public Role(int bloodFlow, int magicPoint)        {            this.bloodFlow = bloodFlow;            this.magicPoint = magicPoint;        }        public int GetBloodFlow()        {            return bloodFlow;        }        public void SetBloodFlow(int bloodFlow)        {            this.bloodFlow = bloodFlow;        }        public int GetMagicPoint()        {            return magicPoint;        }        public void SetMagicPoint(int magicPoint)        {            this.magicPoint = magicPoint;        }        public void Display()        {            Console.WriteLine("用戶當前的狀態：");            Console.WriteLine("血量：" + GetBloodFlow() + ";藍量：" + GetMagicPoint());        }        public Memento SaveMemento()        {            return new Memento(GetBloodFlow (),GetMagicPoint ());        }        public void RestoreMemento(Memento memento)        {            this.bloodFlow = memento.GetBloodFlow();            this.magicPoint = memento.GetMagicPoint();        }    }    class Memento    {        private int bloodFlow;        private int magicPoint;        public Memento(int bloodFlow, int magicPoint)        {            this.bloodFlow = bloodFlow;            this.magicPoint = magicPoint;        }        public int GetBloodFlow()        {            return bloodFlow;        }        public void SetBloodFlow(int bloodFlow)        {            this.bloodFlow = bloodFlow;        }        public int GetMagicPoint()        {            return magicPoint;        }        public void SetMagicPoint(int magicPoint)        {            this.magicPoint = magicPoint;        }    }    class Caretaker    {        public Memento memento;        public Memento GetMemento()        {            return memento;        }        public void SetMemento(Memento memento)        {            this.memento = memento;        }    }