创建型设计模式——抽象工厂模式

提供一个创建一系列相关或相关依赖对象的接口，而无须指定它们具体的类。

适用于

①一个系统要独立于它的产品的创建、组合和表示时。

②一个系统要由多个产品系列中的一个来配置时。

③当要强调一系列相关的产品对象的设计以便进行联合使用时。

④当提供一个产品类库，只想显示它们的接口而不是实现时。

类图如下

    internal class Program
    {
        static void Main(string[] args)
        {
            //初始化用户和部门信息
            User user = new User() { Id = 1, Name = "张善", Age = 27 };
            Department department = new Department() { DeptId = 1, DeptName = "开发" };
            //MySQL操作
            MySqlFactory mySqlFactory = new MySqlFactory();
            mySqlFactory.CreateUser(user);
            mySqlFactory.CreateDepartment(department);
            //SQL server操作
            SqlServerFactory sqlServerFactory = new SqlServerFactory();
            sqlServerFactory.CreateUser(user);
            sqlServerFactory.CreateDepartment(department);

            User mySqlUser = mySqlFactory.GetUser(1);
            Console.WriteLine(mySqlUser.ToString()+",DBName=MySql");
            User sqlServerUser = sqlServerFactory.GetUser(1);
            Console.WriteLine(mySqlUser.ToString() + ",DBName=SqlServer");



        }
    }

    /// <summary>
    /// 用户类，承载用户数据，也可以用接口去扩展
    /// </summary>
    internal class User
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
        public override string ToString()
        {
            return $"Id={Id},Name={Name},Age={Age}";
        }
    }

    /// <summary>
    /// 部门类，承载部门数据，也可以用接口去扩展
    /// </summary>
    internal class Department
    {
        public int DeptId { get; set; }
        public string DeptName { get; set; }
        public override string ToString()
        {
            return $"DeptId={DeptId},DeptName={DeptName}";
        }
    }

    /// <summary>
    /// 抽象工厂，用来创建一系列相关或相关依赖对象，无须指定他们具体的实现类
    /// </summary>
    internal interface IFactory
    {
        public void CreateUser(User user);
        public User GetUser(int Id);
        public void CreateDepartment(Department department);
        public Department GetDepartment(int deptId);
    }

    /// <summary>
    /// SqlServer类，用户往SqlServer写数据和查数据
    /// </summary>
    internal class SqlServerFactory : IFactory
    {
        private List<User> users = new List<User>();
        private List<Department> departments = new List<Department>();
        public void CreateUser(User user)
        {
            Console.WriteLine("SqlServer创建用户");
            users.Add(user);
        }
        public User GetUser(int Id)
        {
            Console.WriteLine("SqlServer查询用户");
            return users.First(s => s.Id == Id);
        }
        public void CreateDepartment(Department department)
        {
            Console.WriteLine("SqlServer创建部门");
            departments.Add(department);
        }
        public Department GetDepartment(int deptId)
        {
            Console.WriteLine("SqlServer查询部门");
            return departments.First(s => s.DeptId == deptId);
        }
    }

    /// <summary>
    /// MySql类，用户往MYsql写数据和查数据
    /// </summary>
    internal class MySqlFactory : IFactory
    {
        private List<User> users = new List<User>();
        private List<Department> departments = new List<Department>();
        public void CreateUser(User user)
        {
            Console.WriteLine("MySql创建用户");
            users.Add(user);
        }
        public User GetUser(int Id)
        {
            Console.WriteLine("MySql查询用户");
            return users.First(s => s.Id == Id);
        }
        public void CreateDepartment(Department department)
        {
            Console.WriteLine("MySql创建部门");
            departments.Add(department);
        }
        public Department GetDepartment(int deptId)
        {
            Console.WriteLine("MySql查询部门");
            return departments.First(s => s.DeptId == deptId);
        }
    }