05. 建造者模式

最新推荐文章于 2025-03-17 01:57:00 发布

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本文通过一个具体的代码示例介绍了建造者模式的基本概念及其与简单工厂模式的区别。通过创建不同的建造者类来实现相同构建过程的不同产品产出，展示了该模式如何在保持构建过程一致性的同时灵活地构造不同类型的产品。

建造者模式：建造过程相同，然后可以建造出不同的产品。简单工厂模式是同一个工厂生产不同的产品。侧重点有些区别。代码示例如下

/**
 * @file builder.h
 * @brief builder pattern
 * @author timeshark
 * @version 1.0
 * @date 2018-08-07
 */

#ifndef BUILDER_H
#define BUILDER_H

#include <iostream>

using std::cout;
using std::endl;

class Builder {
public:
    virtual void build_head() = 0;
    virtual void build_body() = 0;
    virtual void build_left_arm() = 0;
    virtual void build_right_arm() = 0;
    virtual void build_left_leg() = 0;
    virtual void build_right_leg() = 0;
};

class ThinBuilder : public Builder {
public:
    void build_head() { cout << "build thin head" << endl; }
    void build_body() { cout << "build thin body" << endl; }
    void build_left_arm() { cout << "build thin left arm" << endl; }
    void build_right_arm() { cout << "build thin right arm" << endl; }
    void build_left_leg() { cout << "build thin left leg" << endl; }
    void build_right_leg() { cout << "build thin right leg" << endl; }
};

class FatBuilder : public Builder {
public:
    void build_head() { cout << "build fat head" << endl; }
    void build_body() { cout << "build fat body" << endl; }
    void build_left_arm() { cout << "build fat left arm" << endl; }
    void build_right_arm() { cout << "build fat right arm" << endl; }
    void build_left_leg() { cout << "build fat left leg" << endl; }
    void build_right_leg() { cout << "build fat right leg" << endl; }
};

class Director {
public:
    Director(Builder *builder) : _builder(builder) {}

    ~Director() {
        // 注意存在内存泄露问题
        _builder = NULL;
    }

    void create() {
        _builder->build_head();
        _builder->build_body();
        _builder->build_left_arm();
        _builder->build_right_arm();
        _builder->build_left_leg();
        _builder->build_right_leg();
    }

private:
    Builder* _builder;
};

#endif

/**
 * @file main.cpp
 * @brief main
 * @author timeshark
 * @version 1.0
 * @date 2018-08-07
 */

#include "builder.h"

int main() {
    ThinBuilder thin;
    FatBuilder fat;

    Director director(&thin);
    director.create();

    Director director2(&fat);
    director2.create();

    return 0;
}

输出：