设计模式——8.原型模式

原型模式（Prototype）

Prototype模式简介：

使用 原型实例 来指定 所要创建对象 的种类 ，然后通过拷贝 原型实例 来创建新的对象。

Prototype模式结构：

注意事项：

使用原型模式时，要注意浅复制与深复制之间的区别（即C++中默认的复制构造函数或者C#中所有类都继承了的MemberwiseClone方法的使用）

C++代码

//file: Prototype.h
#pragma once
#include "Example.h"

class Prototype
{
public:
	Prototype();
	virtual ~Prototype();
	virtual Prototype* Clone() = 0;
	Example* m_Example;
};

class ConcretePrototype : public Prototype
{
public:
	ConcretePrototype(Example* pE);

	//Use Default Copy Constructor To Get The Shallow Copy ,
	//Or Define The Copy Constructor By Your Self To Get Deep Copy .
	ConcretePrototype(const ConcretePrototype& ref);

	virtual ~ConcretePrototype();

	Prototype* Clone();
};

//file: Prototype.cpp
#include "pch.h"
#include "Prototype.h"

///Prototype
Prototype::Prototype() {}

Prototype::~Prototype() {}


///ConcretePrototype
ConcretePrototype::ConcretePrototype(Example* pE) 
{
	ConcretePrototype::m_Example = pE;
}

//DeepCopy
ConcretePrototype::ConcretePrototype(const ConcretePrototype& ref)
{
	ConcretePrototype::m_Example = new Example();
	ConcretePrototype::m_Example->m_name = ref.m_Example->m_name;
	ConcretePrototype::m_Example->m_level = ref.m_Example->m_level;
}

ConcretePrototype::~ConcretePrototype() {}

Prototype* ConcretePrototype::Clone()
{
	return new ConcretePrototype(*this);
}

客户端代码：

// PrototypePattern.cpp : This file contains the 'main' function. Program execution begins and ends there.
#include "pch.h"
#include "Prototype.h"
#include <iostream>
using namespace std;

int main()
{
	Example* e = new Example();
	Prototype* proto = new ConcretePrototype(e);
	Prototype* copy= proto->Clone();

	cout << (copy->m_Example == proto->m_Example) << endl;
	
	delete proto , copy;

	return 0;
}

输出结果：

深拷贝 0
浅拷贝 1

C#代码

////继承实现原型模式
//public abstract class Prototype
//{
//    public abstract Prototype Clone();
//}

//public class ConcretePrototype : Prototype
//{
//    public override Prototype Clone()
//    {
//        return (ConcretePrototype)this.MemberwiseClone();
//    }
//}


////接口实现原型模式
public class ConcretePrototype : ICloneable
{
	public Example Example { get; set; }

	public ConcretePrototype(Example e)
	{
		this.Example = e;
	}

	////ShallowCopy
	//public object Clone()
	//{
	//    return this.MemberwiseClone();
	//}

	//DeepCopy
	public object Clone()
	{
		Example example = new Example();
		example.Name = this.Example.Name;
		example.Level = this.Example.Level;
		ConcretePrototype prototype = new ConcretePrototype(example);
		return prototype;
	}
}

示例类Example：

public class Example
{
	public string Name { get; set; }
	public string Level { get; set; }

	public Example(string name = "DefaultName", string lv = "123456")
	{
		Name = name;
		Level = lv;
	}
}

客户端调用

class Program
{
	static void Main(string[] args)
	{
		Example e = new Example("sylvan","24");
		ConcretePrototype proto = new ConcretePrototype(e);
		ConcretePrototype copy = (ConcretePrototype)proto.Clone();
		Console.WriteLine("Name : " +  copy.Example.Name + "  Level : " + copy.Example.Level );
		Console.WriteLine(proto.Example.Equals(copy.Example));
		Console.ReadKey();
	}
}

浅拷贝输出为True

深拷贝输出为False

REF

书籍：

设计模式与游戏开发、大话设计模式

GitHub：

https://github.com/me115/design_patterns