抽象工厂模式(大话设计模式)C/C++版本

抽象工厂模式

C++

参考：https://www.cnblogs.com/Galesaur-wcy/p/15927110.html

#include <iostream>
using namespace std;// 抽象产品Department ,定义具体产品的公共接口
class Department
{
public:virtual ~Department() = default;virtual void Insert() = 0;virtual Department *GetDepartment() = 0;
};// 创建具体产品类SqlserDepartment， 定义生产的具体产品；
class SqlserDepartment : public Department
{
public:void Insert() override{cout << "在SQL Server 中给 Department 表增加一条记录！" << endl;}Department *GetDepartment() override{cout << "在SQL Server 中根据ID 得到 Department 表一条记录！" << endl;return nullptr;}
};// 创建具体产品类AccessDepartment， 定义生产的具体产品；
class AccessDepartment : public Department
{
public:void Insert() override{cout << "在 Access 中给 Department 表增加一条记录！" << endl;}Department *GetDepartment() override{cout << "在 Access 中根据ID 得到 Department 表一条记录！" << endl;return nullptr;}
};// 抽象产品User ,定义具体产品的公共接口
class User
{
public:virtual ~User() = default;virtual void Insert() = 0;virtual User *GetUser() = 0;
};// 创建具体产品类SqlserverUser， 定义生产的具体产品；
class SqlserverUser : public User
{
public:void Insert() override{cout << "在SQL Server 中给 User表增加一条记录！" << endl;}User *GetUser() override{cout << "在SQL Server 中根据ID 得到 User表一条记录！" << endl;return nullptr;}
};// 创建具体产品类AccessUser， 定义生产的具体产品；
class AccessUser : public User
{
public:void Insert() override{cout << "在 Access 中给 User表增加一条记录！" << endl;}User *GetUser() override{cout << "在 Access 中根据ID 得到 User表一条记录！" << endl;return nullptr;}
};// 抽象工厂,定义具体工厂的公共接口
class AbstractFactory
{
public:virtual ~AbstractFactory() = default;virtual User *CreateUser() = 0;virtual Department *CreateDepartment() = 0;
};// 创建具体工厂SqlServerFactory,定义创建对应具体产品实例的方法；
class SqlServerFactory : public AbstractFactory
{
public:User *CreateUser() override{return new SqlserverUser(); // 该工厂 生产的产品}Department *CreateDepartment() override{return new SqlserDepartment;}
};// 创建具体工厂AccessFactory，定义创建对应具体产品实例的方法；
class AccessFactory : public AbstractFactory
{
public:User *CreateUser() override{return new AccessUser(); // 该工厂 生产的产品}Department *CreateDepartment() override{return new AccessDepartment;}
};int main()
{// AbstractFactory *factory = new SqlServerFactory;AbstractFactory *factory = new AccessFactory;// 调用的是 AccessFactory 工厂，准备生产  SqlserverUser 产品User *iu = factory->CreateUser();iu->Insert();iu->GetUser();// 调用的是 AccessFactory 工厂，准备生产  AccessDepartment 产品Department *id = factory->CreateDepartment();id->Insert();id->GetDepartment();delete factory;delete iu;delete id;factory = nullptr;id = nullptr;id = nullptr;return 0;
}

C

#include <stdio.h>
#include <stdlib.h>// 抽象产品Department
typedef struct Department
{void (*Insert)(void *);struct Department *(*GetDepartment)(void *);
} Department;// 抽象产品User
typedef struct User
{void (*Insert)(void *);struct User *(*GetUser)(void *);
} User;// 抽象工厂
typedef struct AbstractFactory
{User *(*CreateUser)(void);Department *(*CreateDepartment)(void);
} AbstractFactory;// 具体产品SqlserDepartment
typedef struct SqlserDepartment
{Department base;
} SqlserDepartment;void SqlserDepartment_Insert(void *dept)
{printf("在SQL Server 中给 Department 表增加一条记录！\n");
}Department *SqlserDepartment_GetDepartment(void *dept)
{printf("在SQL Server 中根据ID 得到 Department 表一条记录！\n");return NULL;
}// 具体产品AccessDepartment
typedef struct AccessDepartment
{Department base;
} AccessDepartment;void AccessDepartment_Insert(void *dept)
{printf("在 Access 中给 Department 表增加一条记录！\n");
}Department *AccessDepartment_GetDepartment(void *dept)
{printf("在 Access 中根据ID 得到 Department 表一条记录！\n");return NULL;
}// 具体产品SqlserverUser
typedef struct SqlserverUser
{User base;
} SqlserverUser;void SqlserverUser_Insert(void *user)
{printf("在SQL Server 中给 User表增加一条记录！\n");
}User *SqlserverUser_GetUser(void *user)
{printf("在SQL Server 中根据ID 得到 User表一条记录！\n");return NULL;
}// 具体产品AccessUser
typedef struct AccessUser
{User base;
} AccessUser;void AccessUser_Insert(void *user)
{printf("在 Access 中给 User表增加一条记录！\n");
}User *AccessUser_GetUser(void *user)
{printf("在 Access 中根据ID 得到 User表一条记录！\n");return NULL;
}// 具体工厂SqlServerFactory
typedef struct SqlServerFactory
{AbstractFactory base;
} SqlServerFactory;User *SqlServerFactory_CreateUser(void *unused)
{SqlserverUser *user = (SqlserverUser *)malloc(sizeof(SqlserverUser));user->base.Insert = SqlserverUser_Insert;user->base.GetUser = SqlserverUser_GetUser;return (User *)user;
}Department *SqlServerFactory_CreateDepartment(void *unused)
{SqlserDepartment *dept = (SqlserDepartment *)malloc(sizeof(SqlserDepartment));dept->base.Insert = SqlserDepartment_Insert;dept->base.GetDepartment = SqlserDepartment_GetDepartment;return (Department *)dept;
}// 具体工厂AccessFactory
typedef struct AccessFactory
{AbstractFactory base;
} AccessFactory;User *AccessFactory_CreateUser()
{AccessUser *user = (AccessUser *)malloc(sizeof(AccessUser));user->base.Insert = AccessUser_Insert;user->base.GetUser = AccessUser_GetUser;return (User *)user;
}Department *AccessFactory_CreateDepartment()
{AccessDepartment *dept = (AccessDepartment *)malloc(sizeof(AccessDepartment));dept->base.Insert = AccessDepartment_Insert;dept->base.GetDepartment = AccessDepartment_GetDepartment;return (Department *)dept;
}int main()
{AbstractFactory *factory = (AbstractFactory *)malloc(sizeof(AccessFactory));((AccessFactory *)factory)->base.CreateUser = AccessFactory_CreateUser;((AccessFactory *)factory)->base.CreateDepartment = AccessFactory_CreateDepartment;User *iu = factory->CreateUser();iu->Insert(iu);iu->GetUser(iu);Department *id = factory->CreateDepartment();id->Insert(id);id->GetDepartment(id);free(factory);free(iu);free(id);return 0;
}

总结

在工厂方法模式的基础上，在对应的工厂类中新增了相关产品的创建函数。（其实并不是很方便！！）

扩展：
简单工厂模式似乎更简便点，但是switch部分实在是破坏了开闭原则，可以使用“反射”（即动态识别类型）

C++可以使用静态函数指针数组来实现
参考：https://blog.csdn.net/klarclm/article/details/7352101