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C++ 建造者模式详解

ai 2025/5/14 3:48:10

建造者模式（Builder Pattern）是一种创建型设计模式，它允许你分步骤创建复杂对象，使相同的构建过程可以创建不同的表示。

概念解析

建造者模式的核心思想是：

分离复杂对象的构建和表示：将对象的构建过程与其表示分离
分步构建：允许通过一系列步骤构建复杂对象
灵活配置：相同的构建过程可以创建不同的产品表示

主要组成部分

产品（Product）：最终要构建的复杂对象
抽象建造者（Builder）：定义创建产品各个部件的抽象接口
具体建造者（Concrete Builder）：实现Builder接口，构造和装配产品的各个部件
指挥者（Director）：构建使用Builder接口的对象，控制构建过程
客户端（Client）：创建Director和Builder对象，并启动构建过程

代码示例

下面是一个完整的建造者模式示例，包含详细注释：

#include <iostream>
#include <string>
#include <vector>
#include <memory>// 产品类：汽车
class Car {
private:std::string engine_;std::string transmission_;std::vector<std::string> wheels_;std::vector<std::string> electronics_;public:void setEngine(const std::string& engine) {engine_ = engine;}void setTransmission(const std::string& transmission) {transmission_ = transmission;}void addWheel(const std::string& wheel) {wheels_.push_back(wheel);}void addElectronic(const std::string& electronic) {electronics_.push_back(electronic);}void showDetails() const {std::cout << "汽车配置详情:" << std::endl;std::cout << "发动机: " << engine_ << std::endl;std::cout << "变速箱: " << transmission_ << std::endl;std::cout << "车轮: ";for (const auto& wheel : wheels_) {std::cout << wheel << " ";}std::cout << std::endl;std::cout << "电子设备: ";for (const auto& electronic : electronics_) {std::cout << electronic << " ";}std::cout << std::endl;}
};// 抽象建造者
class CarBuilder {
public:virtual ~CarBuilder() = default;virtual void buildEngine() = 0;virtual void buildTransmission() = 0;virtual void buildWheels() = 0;virtual void buildElectronics() = 0;virtual std::unique_ptr<Car> getCar() = 0;
};// 具体建造者：经济型汽车建造者
class EconomyCarBuilder : public CarBuilder {
private:std::unique_ptr<Car> car_;public:EconomyCarBuilder() {car_ = std::make_unique<Car>();}void buildEngine() override {car_->setEngine("1.5L 自然吸气发动机");}void buildTransmission() override {car_->setTransmission("5速手动变速箱");}void buildWheels() override {for (int i = 0; i < 4; ++i) {car_->addWheel("15寸钢制轮毂");}}void buildElectronics() override {car_->addElectronic("基础音响系统");car_->addElectronic("手动空调");}std::unique_ptr<Car> getCar() override {return std::move(car_);}
};// 具体建造者：豪华型汽车建造者
class LuxuryCarBuilder : public CarBuilder {
private:std::unique_ptr<Car> car_;public:LuxuryCarBuilder() {car_ = std::make_unique<Car>();}void buildEngine() override {car_->setEngine("3.0L V6涡轮增压发动机");}void buildTransmission() override {car_->setTransmission("8速自动变速箱");}void buildWheels() override {for (int i = 0; i < 4; ++i) {car_->addWheel("19寸铝合金轮毂");}}void buildElectronics() override {car_->addElectronic("高级音响系统");car_->addElectronic("自动空调");car_->addElectronic("导航系统");car_->addElectronic("倒车影像");car_->addElectronic("自动驾驶辅助");}std::unique_ptr<Car> getCar() override {return std::move(car_);}
};// 指挥者
class CarManufacturer {
public:std::unique_ptr<Car> buildCar(CarBuilder& builder) {builder.buildEngine();builder.buildTransmission();builder.buildWheels();builder.buildElectronics();return builder.getCar();}
};// 客户端代码
int main() {std::cout << "=== 建造者模式演示 ===" << std::endl;CarManufacturer manufacturer;// 构建经济型汽车std::cout << "\n构建经济型汽车:" << std::endl;EconomyCarBuilder economyBuilder;auto economyCar = manufacturer.buildCar(economyBuilder);economyCar->showDetails();// 构建豪华型汽车std::cout << "\n构建豪华型汽车:" << std::endl;LuxuryCarBuilder luxuryBuilder;auto luxuryCar = manufacturer.buildCar(luxuryBuilder);luxuryCar->showDetails();return 0;
}