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设计模式之:原型模式PrototypePattern的实现(浅克隆和深克隆)(浅表副本和深表副本)

原型模式不是通过new生成新的对象,而使通过复制进行生成;

原型模式适用于相同类型的多个对象的生成;

原型模式分为两种:浅克隆/浅表副本(Shallow Clone)和深克隆/深表副本(Deep Clone);

浅克隆:Shallow Clone,只复制值类型变量,不复制引用类型变量的克隆;(只复制引用类型变量的地址,其实还是指向同一个引用类型)

深克隆:Deep Clone,同时复制值类型和引用类型变量的克隆;

浅克隆用到的技术:

  • Object.MemberwiseClone 方法(命名空间:System),使用该方法可以进行浅克隆;

深克隆用到的技术:

  • BinaryFormatter 类(命名空间:System.Runtime.Serialization.Formatters.Binary),用来将需要克隆的类进行序列化和反序列化;
  • FileStream 类 (命名空间:System.IO),用来将序列化的数据存储到临时文件中,克隆的时候从文件中读取数据;
  • SerializationException 类(命名空间:System.Runtime.Serialization),用来捕获序列化/反序列化过程中的异常;
  • SerializableAttribute 类(命名空间:System),用来对需要克隆的类进行标记,表示改类可以序列化;

类图 with StarUML

浅克隆Shallow Clone

internal class WeeklyLog
    {
        private Attachment attachment;     
        public  Attachment Attachment { get => attachment; set => attachment = value; } 
        /// <summary>
        /// 浅克隆
        /// </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($"下载附件,文件名为:{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("--浅表副本/浅克隆(Shallow Clone)的测试--");
            Console.WriteLine("周报是否相同?{0}", previousLog == newLog ? "是" : "否");
            Console.WriteLine("附件是否相同?{0}", (previousLog.Attachment == newLog.Attachment) ? "是" : "否");
            Console.Read();
        }
    }

运行结果

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($"序列化失败:{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($"反序列化失败:{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($"下载附件,文件名为:{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)的测试--");
            Console.WriteLine("周报是否相同?{0}", previousLog == newLog ? "是" : "否");
            Console.WriteLine("附件是否相同?{0}", (previousLog.Attachment == newLog.Attachment) ? "是" : "否");
            Console.Read();
        }
    }

 运行结果

posted on 2022-04-02 23:56  张德长  阅读(101)  评论(0编辑  收藏  举报