九、建造者模式

建造者模式（Builder）將一個複雜對象的構建與它的表示分離，使得同樣的構建過程可以創建不同的表示。

//Product.h
#ifndef _PRODUCT_H_
#define _PRODUCT_H_

#include <string>
#include <list>
#include <iostream>
using namespace std;

class CProduct
{
public:
    // 添加產品部件
    void Add(const string& strPart)
    {
        m_listPart.push_back(strPart);
    }

    void Show(void)
    {
        cout << "創建 產品 ……\n";
        list<string>::iterator lIter;
        for (lIter = m_listPart.begin(); lIter != m_listPart.end(); lIter++)
        {
            cout << *lIter << endl;
        }
    }

private:
    list<string>    m_listPart;
};

#endif  _PRODUCT_H_

/************************************************************************
 * Builder.h
 * description:	抽象建造者類
 * remark:	Builder是爲創建一個Product對象的各個部件指定的抽象接口	
************************************************************************/
#ifndef _BUILDER_H_
#define _BUILDER_H_

#include "Product.h"

class CBuilder
{
public:
    // 產品由兩個部件PartA和PartB組成
    virtual void BuildPartA(void) = 0;
    virtual void BuildPartB(void) = 0;
    // 得到產品建造後結果
    virtual CProduct* GetResult(void) = 0;
};

#endif  _BUILDER_H_

/************************************************************************
 * ConcreteBuilder.h
 * description:	具體建造者類
 * remark：實現Builder接口，構造和裝配各個部件
************************************************************************/
#ifndef _CONCRETE_BUILDER_H_
#define _CONCRETE_BUILDER_H_

#include "Builder.h"
#include "Product.h"

class CConcreteBuilder1 : public CBuilder
{
public:
    CConcreteBuilder1()
    {
        m_pProduct = NULL;
        m_pProduct = new CProduct();
    }
    
    // 建造具體的部件Alice
    void BuildPartA(void)
    {
        if (NULL != m_pProduct)
        {
            m_pProduct->Add("部件Alice");
        }
    }

    // 建造具體的部件Bob
    void BuildPartB(void)
    {
        if (NULL != m_pProduct)
        {
            m_pProduct->Add("部件Bob");
        }
    }

    CProduct* GetResult(void)
    {
        return m_pProduct;
    }

private:
    CProduct*   m_pProduct;
};

class CConcreteBuilder2 : public CBuilder
{
public:
    CConcreteBuilder2()
    {
        m_pProduct = NULL;
        m_pProduct = new CProduct();
    }

    // 建造具體的部件Carey
    void BuildPartA(void)
    {
        if (NULL != m_pProduct)
        {
            m_pProduct->Add("部件Carey");
        }
    }

    // 建造具體的部件Doom
    void BuildPartB(void)
    {
        if (NULL != m_pProduct)
        {
            m_pProduct->Add("部件Doom");
        }
    }

    CProduct* GetResult(void)
    {
        return m_pProduct;
    }

private:
    CProduct*   m_pProduct;
};

#endif  _CONCRETE_BUILDER_H_

/************************************************************************
 * Director.h
 * description:	指揮者類
 * remark:指揮者類是構建一個使用Builder接口的對象		
************************************************************************/
#ifndef _DIRECTOR_H_
#define _DIRECTOR_H_

#include "Builder.h"

class CDirector
{
public:
    // 用來指揮建造過程
    void Construct(CBuilder* pBuilder)
    {
        pBuilder->BuildPartA();
        pBuilder->BuildPartB();
    }
};

#endif  _DIRECTOR_H_

//main.cpp
#include "stdio.h"
#include "Director.h"
#include "ConcreteBuilder.h"

void FreeMemory(void* Pointer)
{
	if (NULL != Pointer)
	{
		delete Pointer;
	}
}

int main()
{
	CDirector* pDirector = NULL;
	pDirector = new CDirector();

	CBuilder* pBuilder1 = new CConcreteBuilder1();
	CBuilder* pBuilder2 = new CConcreteBuilder2();

	// 指揮者用CConcreteBuilder1的方法來建造產品
	if (NULL != pDirector)
	{     
		pDirector->Construct(pBuilder1);
		CProduct* pProduct1 = pBuilder1->GetResult();
		if (NULL != pProduct1)
		{
			pProduct1->Show();
		}
	}

	if (NULL != pDirector)
	{
		pDirector->Construct(pBuilder2);
		CProduct* pProduct2 = pBuilder2->GetResult();
		if (NULL != pProduct2)
		{
			pProduct2->Show();
		}
	}

	FreeMemory(pDirector);
	FreeMemory(pBuilder1);
	FreeMemory(pBuilder2);
	return 0;
}