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
{ 8     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};
ID = {3}
",
            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 *****
");
            Console.WriteLine("Cloned p3 and stored new Point in p4");
            Point p3 = new Point(100, 100, "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 = 9;

            Console.WriteLine("
Changed 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};
ID = {3}
",
            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 *****
");
            Console.WriteLine("Cloned p3 and stored new Point in p4");
            Point p3 = new Point(100, 100, "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 = 9;

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