設計模式之：原型模式PrototypePattern的實現（淺克隆和深克隆）（淺表副本和深表副本）

原型模式不是通過new生成新的對象，而使通過複製進行生成；

原型模式適用於相同類型的多個對象的生成；

原型模式分為兩種：淺克隆/淺表副本（Shallow Clone）和深克隆/深表副本（Deep Clone）；

淺克隆：Shallow Clone，只複製值類型變數，不複製引用類型變數的克隆；（只複製引用類型變數的地址，其實還是指向同一個引用類型）

深克隆：Deep Clone，同時複製值類型和引用類型變數的克隆；

淺克隆用到的技術：

• Object.MemberwiseClone 方法（命名空間:System），使用該方法可以進行淺克隆；

深克隆用到的技術：

• BinaryFormatter 類（命名空間:System.Runtime.Serialization.Formatters.Binary），用來將需要克隆的類進行序列化和反序列化；
• FileStream 類 （命名空間:System.IO），用來將序列化的數據存儲到臨時文件中，克隆的時候從文件中讀取數據；
• SerializationException 類（命名空間:System.Runtime.Serialization），用來捕獲序列化/反序列化過程中的異常；
• SerializableAttribute 類（命名空間:System），用來對需要克隆的類進行標記，表示改類可以序列化；

類圖 with StarUML

淺克隆Shallow Clone

internal class WeeklyLog
    {
        private Attachment attachment;     
        public  Attachment Attachment { get => attachment; set => attachment = value; } 
        /// <summary>
        /// 淺克隆
        /// </summary>
        /// <returns></returns>
        public WeeklyLog ShallowClone()
        {
            return this.MemberwiseClone() as WeeklyLog;
        }
    }

    internal class Attachment
    {
        private string name;
        public string Name { get => name; set => name = value; }
        public void DownLoad() { Console.WriteLine($"下載附件，文件名為：{name}"); }
    }

    internal class Program
    {
        static void Main(string[] args)
        {
            WeeklyLog previousLog, newLog;
            previousLog = new WeeklyLog();

            Attachment attachment = new Attachment();
            previousLog.Attachment = attachment;
            newLog = previousLog.ShallowClone();

            Console.WriteLine("--淺表副本/淺克隆（Shallow Clone）的測試--");
            Console.WriteLine("周報是否相同？{0}", previousLog == newLog ? "是" : "否");
            Console.WriteLine("附件是否相同？{0}", (previousLog.Attachment == newLog.Attachment) ? "是" : "否");
            Console.Read();
        }
    }

運行結果

深克隆Deep Clone

[Serializable]
    internal class WeeklyLog
    {
        private Attachment attachment;
        public Attachment Attachment { get => attachment; set => attachment = value; }
        /// <summary>
        /// 深克隆DeepClone
        /// </summary>
        /// <returns></returns>
        public WeeklyLog DeepClone()
        {
            WeeklyLog clone = null;

            FileStream stream1 = new FileStream("Temp.dat", FileMode.Create);
            BinaryFormatter formatter1 = new BinaryFormatter();
            //序列化
            try { formatter1.Serialize(stream1, this); }
            catch (SerializationException ex) { Console.WriteLine($"序列化失敗：{ex.Message}"); }
            finally { stream1.Close(); }

            FileStream stream2 = new FileStream("Temp.dat", FileMode.Open);
            BinaryFormatter formatter2 = new BinaryFormatter();
            //反序列化
            try { clone = formatter2.Deserialize(stream2) as WeeklyLog; }
            catch (SerializationException ex) { Console.WriteLine($"反序列化失敗：{ex.Message}"); }
            finally { stream2.Close(); }

            return clone;
        }
    }

    [Serializable]
    internal class Attachment
    {
        private string name;
        public string Name { get => name; set => name = value; }
        public void DownLoad() { Console.WriteLine($"下載附件，文件名為：{name}"); }
    }

internal class Program
    {
        static void Main(string[] args)
        {
            WeeklyLog previousLog, newLog;
            previousLog = new WeeklyLog();

            Attachment attachment = new Attachment();
            previousLog.Attachment = attachment;
            newLog = previousLog.DeepClone();

            Console.WriteLine("--深表副本/深克隆（Deep Clone）的測試--");
            Console.WriteLine("周報是否相同？{0}", previousLog == newLog ? "是" : "否");
            Console.WriteLine("附件是否相同？{0}", (previousLog.Attachment == newLog.Attachment) ? "是" : "否");
            Console.Read();
        }
    }

 運行結果