生成器模式是一种创建型设计模式，用于分步骤创建复杂对象，从而隐藏构建过程的细节。并且相同的创建代码可以生成不同类型和形式的对象。

什么是复杂对象？

在面向对象的编程中，实际体现的就是一个类的构造函数。有这么一个类，它有很多成员变量，成员变量中有简单的类型对象，也有其他用户自定义的类型对象。需要在构造函数中对这些成员变量进行初始化工作。构造函数带了很多参数，用于不同成员变量的初始化。

解决的问题

创建这样的对象，通常要传递很多参数，其中有很多是没用的。并且要在构造函数里做很多if判断。

类图

![2024-01-08T23:45:55.png][1]

示例代码

```c++

include

include

// 1. 产品 - 计算机 class Computer { public: void setMotherboard(const std::string& motherboard) { motherboard_ = motherboard; }

void setCPU(const std::string& cpu) {
    cpu_ = cpu;
}

void setMemory(const std::string& memory) {
    memory_ = memory;
}

void setStorage(const std::string& storage) {
    storage_ = storage;
}

void display() const {
    std::cout << "Computer Configuration:" << std::endl;
    std::cout << "Motherboard: " << motherboard_ << std::endl;
    std::cout << "CPU: " << cpu_ << std::endl;
    std::cout << "Memory: " << memory_ << std::endl;
    std::cout << "Storage: " << storage_ << std::endl;
}

private: std::string motherboard; std::string cpu; std::string memory; std::string storage; };

// 2. 生成器接口 class ComputerBuilder { public: virtual void buildMotherboard() = 0; virtual void buildCPU() = 0; virtual void buildMemory() = 0; virtual void buildStorage() = 0; virtual Computer getResult() = 0; };

// 3. 具体生成器 - 高性能计算机生成器 class HighPerformanceComputerBuilder : public ComputerBuilder { public: void buildMotherboard() override { computer_.setMotherboard("High-Performance Motherboard"); }

void buildCPU() override {
    computer_.setCPU("High-Performance CPU");
}

void buildMemory() override {
    computer_.setMemory("High-Performance Memory");
}

void buildStorage() override {
    computer_.setStorage("SSD Storage");
}

Computer getResult() override {
    return computer_;
}

private: Computer computer_; };

// 4. 具体生成器 - 普通计算机生成器 class RegularComputerBuilder : public ComputerBuilder { public: void buildMotherboard() override { computer_.setMotherboard("Regular Motherboard"); }

void buildCPU() override {
    computer_.setCPU("Regular CPU");
}

void buildMemory() override {
    computer_.setMemory("Regular Memory");
}

void buildStorage() override {
    computer_.setStorage("HDD Storage");
}

Computer getResult() override {
    return computer_;
}

private: Computer computer_; };

// 5. 指导者 class ComputerDirector { public: Computer buildComputer(ComputerBuilder& builder) { builder.buildMotherboard(); builder.buildCPU(); builder.buildMemory(); builder.buildStorage(); return builder.getResult(); } };

int main() { // 使用生成器模式构建高性能计算机 HighPerformanceComputerBuilder highPerformanceBuilder; ComputerDirector director; Computer highPerformanceComputer = director.buildComputer(highPerformanceBuilder); highPerformanceComputer.display();

std::cout << std::endl;

// 使用生成器模式构建普通计算机
RegularComputerBuilder regularBuilder;
Computer regularComputer = director.buildComputer(regularBuilder);
regularComputer.display();

return 0;

}

  [1]: https://lcslearn.top/usr/uploads/2024/01/2919553206.png