构建可克隆的对象（ICloneable）

ICloneable接口

　　如果想使自己的自定义类型支持向调用方返回自身同样副本的能力，需要实现标准ICloneable接口。

 namespace System
 {     public interface ICloneable
     {
         object Clone();
     }
 }

浅拷贝

　　System.Object定义了一个名为MemberwiseClone()的成员。这个方法用来获取当前对象的一份浅拷贝。

例：

Point.cs

 namespace CloneablePoint
 {
     // The Point now supports "clone-ability."
     public class Point : ICloneable
     {
         public int X { get; set; }
         public int Y { get; set; }
         public PointDescription desc = new PointDescription();

         public Point( int xPos, int yPos, string petName )
         {
             X = xPos; Y = yPos;
             desc.PetName = petName;
         }
         public Point( int xPos, int yPos )
         {
             X = xPos; Y = yPos;
         }
         public Point() { }

         // Override Object.ToString().
         public override string ToString()
         {
             return string.Format("X = {0}; Y = {1}; Name = {2};\nID = {3}\n",
             X, Y, desc.PetName, desc.PointID);
         }

         // Return a copy of the current object.
         // Now we need to adjust for the PointDescription member.
         public object Clone()
         {
             // 这个复制每个Ponit字段成员
             Point newPoint = (Point)this.MemberwiseClone();
             return newPoint;
         }
     }
 }

PointDescription.cs

 namespace CloneablePoint
 {
     // This class describes a point.
     public class PointDescription
     {
         public string PetName { get; set; }
         public Guid PointID { get; set; }

         public PointDescription()
         {
             PetName = "No-name";
             PointID = Guid.NewGuid();
         }
     }
 }

Program.cs

 namespace CloneablePoint
 {
     class Program
     {
         static void Main( string[] args )
         {
             Console.WriteLine("***** Fun with Object Cloning *****\n");
             Console.WriteLine("Cloned p3 and stored new Point in p4");
             Point p3 = new Point(, , "Jane");
             Point p4 = (Point)p3.Clone();

             Console.WriteLine("Before modification:");
             Console.WriteLine("p3: {0}", p3);
             Console.WriteLine("p4: {0}", p4);
             p4.desc.PetName = "My new Point";
             p4.X = ;

             Console.WriteLine("\nChanged p4.desc.petName and p4.X");
             Console.WriteLine("After modification:");
             Console.WriteLine("p3: {0}", p3);
             Console.WriteLine("p4: {0}", p4);
             Console.ReadLine();
         }
     }
 }

　　请注意，如果Ponint包含任何引用类型成员变量，MemberwiseClone()将这些引用复制到对象中（即浅复制）。如果想要支持真正的深复制，需要在克隆过程中创建任何引用类型变量的新实力。

深拷贝

Point.cs

namespace CloneablePoint
{
    public class Point : ICloneable
    {
        public int X { get; set; }
        public int Y { get; set; }
        public PointDescription desc = new PointDescription();

        public Point( int xPos, int yPos, string petName )
        {
            X = xPos; Y = yPos;
            desc.PetName = petName;
        }
        public Point( int xPos, int yPos )
        {
            X = xPos; Y = yPos;
        }
        public Point() { }

        public override string ToString()
        {
            return string.Format("X = {0}; Y = {1}; Name = {2};\nID = {3}\n",
            X, Y, desc.PetName, desc.PointID);
        }

        public object Clone()
        {
            Point newPoint = (Point)this.MemberwiseClone();

            PointDescription currentDesc = new PointDescription();
            currentDesc.PetName = this.desc.PetName;
            newPoint.desc = currentDesc;
            return newPoint;
        }
    }
}

PointDescription.cs

namespace CloneablePoint
{
    public class PointDescription
    {
        public string PetName { get; set; }
        public Guid PointID { get; set; }

        public PointDescription()
        {
            PetName = "No-name";
            PointID = Guid.NewGuid();
        }
    }
}

Program.cs

namespace CloneablePoint
{
    class Program
    {
        static void Main( string[] args )
        {
            Console.WriteLine("***** Fun with Object Cloning *****\n");
            Console.WriteLine("Cloned p3 and stored new Point in p4");
            Point p3 = new Point(, , "Jane");
            Point p4 = (Point)p3.Clone();

            Console.WriteLine("Before modification:");
            Console.WriteLine("p3: {0}", p3);
            Console.WriteLine("p4: {0}", p4);
            p4.desc.PetName = "My new Point";
            p4.X = ;

            Console.WriteLine("\nChanged p4.desc.petName and p4.X");
            Console.WriteLine("After modification:");
            Console.WriteLine("p3: {0}", p3);
            Console.WriteLine("p4: {0}", p4);
            Console.ReadLine();
        }
    }
}