如果要构建的对象很复杂，那么可以将整个构建过程拆分成多个步骤，并为每一个步骤定义一个抽象的接口。并添加一个指导者用来控制构建产品的顺序和步骤。

Java实现： 

// 产品类
class Product {
    private String part1;
    private String part2;

    public void setPart1(String part1) {
        this.part1 = part1;
    }
    public void setPar2(String part2) {
        this.part2 = part2;
    }
    // 其他属性和方法
}

// 抽象建造者接口
interface Builder {
    void buildPart1(String part1);
    void buildPart2(String part2);
    Product getResult();
}

// 具体建造者类
class ConcreteBuilder implements Builder {
    private Product product = new Product();

    @Override
    public void buildPart1(String part1) {
        product.setPart1(part1);
    }

    @Override
    public void buildPart2(String part2) {
        product.setPart2(part2);
    }

    @Override
    public Product getResult() {
        return product;
    }
}
// 指导者类
class Director {
    private Builder builder;

    public Director(Builder builder) {
        this.builder = builder;
    }
    // 调用方法构建产品
    public void construct() {
        builder.buildPart1("Part 1");
        builder.buildPart2("Part 2");
    }
}

public class Main {
    public static void main(String[] args) {
        // 创建指导者和建造者对象
        Builder builder = new ConcreteBuilder();
        Director director = new Director(builder);

        // 指导者构建产品
        director.construct();

        // 获取构建好的产品
        Product product = builder.getResult();

        // 输出产品信息
        System.out.println(product);
    }
}

 【设计模式专题之建造者模式】4. 自行车加工

CPP版题解：

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

class Bike {
public:
    string frame;
    string tires;
    
    void setFrame(const string& frame) {
        this->frame = frame;
    }
    
    void setTires(const string& tires) {
        this->tires = tires;
    }
    friend ostream& operator << (ostream& os, const Bike& bike) {
        os << bike.frame << " " << bike.tires;
        return os;
    }
};

class BikeBuilder {
public:
    virtual void buildFrame() = 0;
    virtual void buildTires() = 0;
    virtual Bike getResult() = 0;
};

class MountainBikeBuilder : public BikeBuilder {
private:
    Bike bike;
public:
    void buildFrame() override {
        bike.setFrame("Aluminum Frame");
    }
    
    void buildTires() override {
        bike.setTires("Knobby Tires");
    }
    
    Bike getResult() override {
        return bike;
    }
};
class RoadBikeBuilder : public BikeBuilder {
private:
    Bike bike;
public:
    void buildFrame() override {
        bike.setFrame("Carbon Frame");
    }
    void buildTires() override {
        bike.setTires("Slim Tires");
    }
    Bike getResult() override {
        return bike;
    }
};

class BikeDirector {
public:
    Bike construct(BikeBuilder& builder) {
        builder.buildFrame();
        builder.buildTires();
        return builder.getResult();
    }
};

int main() {
    int N;
    cin >> N;
    
    BikeDirector director;
    
    for (int i = 0; i < N; i++) {
        string bikeType;
        cin >> bikeType;
        
        BikeBuilder* builder;
        
        if (bikeType == "mountain") {
            builder = new MountainBikeBuilder();
        } else {
            builder = new RoadBikeBuilder();
        }
        
        Bike bike = director.construct(*builder);
        cout << bike << endl;
        
        delete builder;
    }
    return 0;
}