建造者模式 C++实现

//
//  main.cpp
//  builder_pattern
//
//  Created by apple on 2019/3/12.
//  Changed by apple on 2019/3/31
//  Copyright © 2019年 apple. All rights reserved.
//

#include <iostream>
#include <string>
using std::cout;
using std::endl;

class IProduct//抽象产品类
{
public:
    int num = 0;
    virtual ~IProduct() {}
    virtual void product() {this->num++;}
    virtual void test() = 0;
};
class Product:public IProduct//实际产品
{
public:
    void test(){cout<<"level "<<this->num<<" product succeed!"<<endl;}
};

class IBuilder//建造者接口定义了建造者的建造方法
{
public:
    IProduct *product = NULL;
    virtual void first_step() = 0;
    virtual void second_step() = 0;
    virtual void third_step() = 0;
    virtual IProduct *GetProduct() = 0;
    virtual ~IBuilder() {}
};
class Builder_A:public IBuilder//A建造者
{//建造者可以拥有很多用于构造产品的方法
public:
    Builder_A() {this->product = new Product();}
    void first_step(){product->product();cout<<"Builder_A first_step"<<endl;}
    void second_step(){product->product();cout<<"Builder_A second_step"<<endl;}
    void third_step(){product->product();cout<<"Builder_A third_step"<<endl;}
    IProduct *GetProduct(){
        return product;
    }
    ~Builder_A() {delete product;}
};
class Builder_B:public IBuilder//B_建造者
{//建造者可以拥有很多用于构造产品的方法
public:
    Builder_B() {this->product = new Product();}
    void first_step(){product->product();cout<<"Builder_B first_step"<<endl;}
    void second_step(){product->product();cout<<"Builder_B second_step"<<endl;}
    void third_step(){}//注意third_step方法的区别
    IProduct *GetProduct(){
        return product;
    }
    ~Builder_B() {delete product;}
};
class Director//导演类，使建造者执行命令
{
private:
    IBuilder *builder;
public:
    void setBuilder(IBuilder *builder){this->builder = builder;}
    void command_A(){
        builder->first_step();
        builder->second_step();
        builder->third_step();
        this->builder->GetProduct();
        cout<<"Director command succeed by command_A."<<endl;
    }
    void command_B(){
        builder->first_step();
        builder->second_step();
        builder->third_step();
        this->builder->GetProduct();
        cout<<"Director command succeed by command_B."<<endl;
    }
};

int main(int argc, const char * argv[]) {
    Director director;//栈上导演
    IBuilder *builder = NULL;//堆上建造者
    
    builder = new Builder_A();
    director.setBuilder(builder);
    director.command_A();
    builder->GetProduct()->test();
    delete builder;
    builder = NULL;
    
    builder = new Builder_B();
    director.setBuilder(builder);
    director.command_B();
    builder->GetProduct()->test();
    delete builder;
    builder = NULL;
    return 0;
}

Builder_A first_step
Builder_A second_step
Builder_A third_step
Director command succeed by command_A.
level 3 product succeed!
Builder_B first_step
Builder_B second_step
Director command succeed by command_B.
level 2 product succeed!
Program ended with exit code: 0