3.建造模式（Builder）

注：图片来源于 https://www.cnblogs.com/-saligia-/p/10216752.html

建造模式UML图解析：

代码：

Director.h

//
// Created by DELL on 2019/10/15.
//

#ifndef BUILDER_DIRECTOR_H
#define BUILDER_DIRECTOR_H

#include "Builder.h"
class Director {
public:
    explicit Director(PhoneBuilder* pb) {
        builder = pb;
    }
    void BuildPlan() {
        builder->BuildOS();
        builder->BuildShape();
        builder->BuildMemory();
        builder->ShowDetail();
    }
private:
    PhoneBuilder* builder;
};

#endif //BUILDER_DIRECTOR_H

Builder.h

//
// Created by DELL on 2019/10/15.
//

#ifndef BUILDER_BUILDER_H
#define BUILDER_BUILDER_H

#include "Product.h"
class PhoneBuilder {
public:
    virtual void BuildOS() = 0;
    virtual void BuildShape() = 0;
    virtual void BuildMemory() = 0;
    virtual void ShowDetail() = 0;
};

class HUAWEIBuilder : public PhoneBuilder {
public:
    HUAWEIBuilder() {
        phone = new Phone();
    }
    void BuildOS() override {
        phone->SetOS("HMOS");
    }
    void BuildShape() override {
        phone->SetShape("6.2inch");
    }
    void BuildMemory() override {
        phone->SetMemory("8G");
    }
    void ShowDetail() override {
        phone->showDetail();
    }
private:
    Phone* phone;
};

class OPPOBuilder : public PhoneBuilder {
public:
    OPPOBuilder() {
        phone = new Phone();
    }
    void BuildOS() override {
        phone->SetOS("ColorOS");
    }
    void BuildShape() override {
        phone->SetShape("6.5inch");
    }
    void BuildMemory() override {
        phone->SetMemory("6G");
    }
    void ShowDetail() override {
        phone->showDetail();
    }
private:
    Phone* phone;
};
#endif //BUILDER_BUILDER_H

Product.h

//
// Created by DELL on 2019/10/15.
//

#ifndef BUILDER_PRODUCT_H
#define BUILDER_PRODUCT_H

#include <string>
#include <utility>
#include <iostream>
//产品类-手机
class Phone {
public:
    Phone() : phone_os("Android"), phone_shape("5 inch"), phone_memory("4G"){}
    //set成员函数用于设置private成员变量
    void SetOS(std::string os) {
        phone_os = std::move(os);
    }
    void SetShape(std::string shape) {
        phone_shape = std::move(shape);
    }
    void SetMemory(std::string memory) {
        phone_memory = std::move(memory);
    }
    void showDetail() {
        std::cout << phone_os << " " << phone_shape <<  " " << phone_memory << std::endl;
    }

private:
    std::string phone_os;
    std::string phone_shape;
    std::string phone_memory;
};

#endif //BUILDER_PRODUCT_H

用户 main.cpp

#include <iostream>
#include "Director.h"
#include "Builder.h"
using namespace std;

int main() {
    PhoneBuilder* hw = new HUAWEIBuilder();
    auto* dr1 = new Director(hw);
    dr1->BuildPlan();

    PhoneBuilder* op = new OPPOBuilder();
    auto* dr2 = new Director(op);
    dr2->BuildPlan();

    return 0;
}

 注：工厂模式与建造模式最大区别在于：工厂模式关注如何获取实例对象，而建造模式关注如何建造实例对象。

工厂模式直接产出产品，不关注细节，而建造模式关注的是产品的细节，关心如何构造产品的每个细节进而组合成完整产品。

以上是两种模式的区别。