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【二】【设计模式】建造者模式

news 2025/9/13 0:34:25

建造者模式的引入

//C10_1.cpp
#include <stdio.h>#include "SystemConfig.h"int main() {SystemConfig config("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda","redis://127.0.0.1/", "xiaomuredis", "xiaomuredispw","kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw");SystemConfig config2("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda","", "", "","kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw");SystemConfig config3("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda","kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw","", "", "");return 0;
}

在C10_1.cpp中，首先包含了SystemConfig.h头文件以访问SystemConfig类。然后在main函数中，创建了三个SystemConfig对象，每个对象都用不同的参数初始化。这三个对象分别为config、config2和config3，它们代表不同的配置集。每个对象的构造函数都传入了MySQL、Redis和Kafka的URL、用户名和密码。在config2和config3中，某些服务的参数为空字符串，表示不使用该服务。

//SystemConfig.h
#pragma once#include <string>class SystemConfig
{
public:SystemConfig(const std::string & _MySQL_URL, const std::string & _MySQL_USER, const std::string & _MySQL_PW,const std::string & _Redis_URL, const std::string & _Redis_USER, const std::string & _Redis_PW,const std::string& _Kafka_URL, const std::string& _Kafka_USER, const std::string& _Kafka_PW);std::string MySQL_URL;std::string MySQL_USER;std::string MySQL_PW;std::string Redis_URL;std::string Redis_USER;std::string Redis_PW;std::string Kafka_URL;std::string Kafka_USER;std::string Kafka_PW;
};

SystemConfig.h是SystemConfig类的头文件。它声明了SystemConfig类及其构造函数和成员变量。构造函数接受MySQL、Redis和Kafka的URL、用户名和密码作为参数。这些参数被用来初始化对象的公共成员变量。使用#pragma once防止头文件被多次包含。

//SystemConfig.cpp
#include "SystemConfig.h"SystemConfig::SystemConfig(const std::string& _MySQL_URL, const std::string& _MySQL_USER, const std::string& _MySQL_PW,const std::string& _Redis_URL, const std::string& _Redis_USER, const std::string& _Redis_PW,const std::string& _Kafka_URL, const std::string& _Kafka_USER, const std::string& _Kafka_PW)
{MySQL_URL = _MySQL_URL;MySQL_USER = _MySQL_USER;MySQL_PW = _MySQL_PW;Redis_USER = _Redis_USER;Redis_URL = _Redis_URL;Redis_PW = _Redis_PW;Kafka_USER = _Kafka_USER;Kafka_URL = _Kafka_URL;Kafka_PW = _Kafka_PW;
}

SystemConfig.cpp是SystemConfig类的源文件。它定义了SystemConfig类构造函数内部的代码逻辑，利用接受的MySQL、Redis和Kafka的URL、用户名和密码的参数，对应的赋值给SystemConfig类的成员变量。

建造者模式

//C10_2.cpp
#include <stdio.h>#include "SystemConfig.h"#include "SystemConfigBuilder.h"#include "CompanyA.h"
#include "CompanyB.h"int main()
{/*SystemConfig config("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda","redis://127.0.0.1/", "xiaomuredis", "xiaomuredispw","kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw");SystemConfig config2;config2.setMySQL("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda");config2.setRedis("redis://127.0.0.1/", "xiaomuredis", "xiaomuredispw");config2.setKafka("kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw");*/SystemConfigBuilder builder; builder.setMySQL("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda");builder.setRedis("redis://127.0.0.1/", "xiaomuredis", "xiaomuredispw");builder.setKafka("kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw");SystemConfig config = builder.getSystemConfig();printf("Mysql URL: %s\n", config.MySQL_URL.c_str());printf("Mysql USER: %s\n", config.MySQL_USER.c_str());printf("Mysql PW %s\n", config.MySQL_PW.c_str());printf("Redis URL: %s\n", config.Redis_URL.c_str());printf("Redis USER: %s\n", config.Redis_USER.c_str());printf("Redis PW %s\n", config.Redis_PW.c_str());printf("Kafka URL: %s\n", config.Kafka_URL.c_str());printf("Kafka USER: %s\n", config.Kafka_USER.c_str());printf("Kafka PW %s\n", config.Kafka_PW.c_str());CompanyA companyA;SystemConfig configA = companyA.buildSystemConfig();CompanyB companyB;SystemConfig configB = companyB.buildSystemConfig();return 0;
}

//SystemConfig.h
#pragma once#include <string>class SystemConfig
{
public:SystemConfig();SystemConfig(const std::string & _MySQL_URL, const std::string & _MySQL_USER, const std::string & _MySQL_PW,const std::string & _Redis_URL, const std::string & _Redis_USER, const std::string & _Redis_PW,const std::string& _Kafka_URL, const std::string& _Kafka_USER, const std::string& _Kafka_PW);std::string MySQL_URL;std::string MySQL_USER;std::string MySQL_PW;std::string Redis_URL;std::string Redis_USER;std::string Redis_PW;std::string Kafka_URL;std::string Kafka_USER;std::string Kafka_PW;
};

//SystemConfig.cpp
#include "SystemConfig.h"SystemConfig::SystemConfig()
{}SystemConfig::SystemConfig(const std::string& _MySQL_URL, const std::string& _MySQL_USER, const std::string& _MySQL_PW,const std::string& _Redis_URL, const std::string& _Redis_USER, const std::string& _Redis_PW,const std::string& _Kafka_URL, const std::string& _Kafka_USER, const std::string& _Kafka_PW)
{MySQL_URL = _MySQL_USER;MySQL_USER = _MySQL_URL;MySQL_PW = _MySQL_PW;Redis_USER = _Redis_USER;Redis_URL = _Redis_URL;Redis_PW = _Redis_PW;Kafka_USER = _Kafka_USER;Kafka_URL = _Kafka_URL;Kafka_PW = _Kafka_PW;
}

//SystemConfigBuilder.h
#pragma once#include "SystemConfig.h"class SystemConfigBuilder
{
public:SystemConfig config;int setMySQL(const std::string& _MySQL_URL, const std::string& _MySQL_USER, const std::string& _MySQL_PW);int setRedis(const std::string& _Redis_URL, const std::string& _Redis_USER, const std::string& _Redis_PW);int setKafka(const std::string& _Kafka_URL, const std::string& _Kafka_USER, const std::string& _Kafka_PW);SystemConfig& getSystemConfig();
};

SystemConfigBuilder.h是SystemConfigBuilder类的头文件，声明了SystemConfig类成员变量，以及setMySQL、setRedis、setKafka，三个成员函数，分别用来配置MySQL、Redis、Kafka。以及getSystemConfig成员函数用来获取对应的SystemConfig类系统配置。

//SystemConfigBuilder.cpp
#include "SystemConfigBuilder.h"SystemConfig& SystemConfigBuilder::getSystemConfig()
{return config;
}int SystemConfigBuilder::setMySQL(const std::string& _MySQL_URL, const std::string& _MySQL_USER, const std::string& _MySQL_PW)
{config.MySQL_URL = _MySQL_USER;config.MySQL_USER = _MySQL_URL;config.MySQL_PW = _MySQL_PW;return 0;
}int SystemConfigBuilder::setRedis(const std::string& _Redis_URL, const std::string& _Redis_USER, const std::string& _Redis_PW)
{config.Redis_USER = _Redis_USER;config.Redis_URL = _Redis_URL;config.Redis_PW = _Redis_PW;return 0;
}int SystemConfigBuilder::setKafka(const std::string& _Kafka_URL, const std::string& _Kafka_USER, const std::string& _Kafka_PW)
{config.Kafka_USER = _Kafka_USER;config.Kafka_URL = _Kafka_URL;config.Kafka_PW = _Kafka_PW;return 0;
}

SystemConfigBuilder.cpp是SystemConfigBuilder类的源文件，对SystemConfigBuilder.h中的声明进行了定义。

//Director.h
#pragma once#include "SystemConfig.h"
#include "SystemConfigBuilder.h"class Director
{
public:SystemConfigBuilder builder;virtual SystemConfig& buildSystemConfig() = 0;
};

Director.h是Director导演类的头文件，我们利用SystemConfigBuilder类可以很方便地完成系统的配置，但对于不同的公司他们提供的服务不同，有些公司只需要配置MySQL和Kafka，有些公司只配置MySQL和Redis。对于不同的公司运用SystemConfigBuilder类的情况不同，因此我们为不同的公司准备不同的调用方案，到时候只需要使用一个函数就可以完成配置。将调用函数配置行为进行封装。

Director的目的是为了封装控制SystemConfigBuilder 类，因此构造一个纯虚函数buildSystemConfig，用来表示不同公司对于SystemConfigBuilder 的使用情况。

//Director.cpp
#include "Director.h"

//CompanyA.h
#pragma once#include "SystemConfig.h"
#include "SystemConfigBuilder.h"#include "Director.h"class CompanyA : public Director
{
public:virtual SystemConfig & buildSystemConfig() override;
};

//CompanyA.cpp
#include "CompanyA.h"SystemConfig& CompanyA::buildSystemConfig()
{builder.setMySQL("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda");builder.setRedis("", "", "");builder.setKafka("kafka://127.0.0.1", "xiaomukafka", "xiaomukafkapw");return builder.getSystemConfig();
}

CompanyA公司只配置MySQL和Kafka，因此buildSystemConfig函数调用setRedis参数为空。

//CompanyB.h
#pragma once#include "SystemConfig.h"
#include "SystemConfigBuilder.h"#include "Director.h"class CompanyB : public Director
{
public:virtual SystemConfig& buildSystemConfig() override;
};

//CompanyB.cpp
#include "CompanyB.h"SystemConfig& CompanyB::buildSystemConfig()
{builder.setMySQL("mysql://127.0.0.1/", "xiaomu", "xiaomumemeda");builder.setRedis("redis://127.0.0.1/", "xiaomuredis", "xiaomuredispw");builder.setKafka("", "", "");return builder.getSystemConfig();
}

CompanyB公司只配置MySQL和Redis，因此buildSystemConfig函数调用setKafka参数为空。