【設計模式】之抽象工廠模式（反射+配置文件）

• UML

• 舉例

//User Table
class User
    {
        private int _id;                //ID
        private string _name;           //姓名

        public int ID{ get => _id; set => _id = value; }
        public string Name { get => _name; set => _name = value; }
    }

//Department Table
class Department
    {
        private int _id;
        private string _name;

        public int Id { get => _id; set => _id = value; }
        public string Name { get => _name; set => _name = value; }
    }

	//User操縱接口
    interface IUser
    {
        void Insert(User user);
        User GetUser(int id);
    }

//用於操縱Access中的User表
class AccessUser : IUser
    {
        public User GetUser(int id)
        {
            Console.WriteLine("在Access中根據ID得到User表一條記錄");
            return null;
        }

        public void Insert(User user)
        {
            Console.WriteLine("在Access中給User表增加一條記錄");
        }
    }

	//用於操縱Sql Server中的User表
    class SqlserverUser:IUser
    {
        public void Insert(User user)
        {
            Console.WriteLine("在SQL Server中給User表增加一條記錄");
        }

        public User GetUser(int id)
        {
            Console.WriteLine("在SQL Server中根據ID得到User表一條記錄");
            return null;
        }
    }

	//Department操縱接口
    interface IDepartment
    {
        void Insert(Department department);
        Department GetDepartment(int id);
    }

//用於操縱Access Server中的Department表
class AccessDepartment : IDepartment
    {
        public Department GetDepartment(int id)
        {
            Console.WriteLine("在Access數據庫中根據id獲取一條Department數據");
            return null;
        }
        public void Insert(Department department)
        {
            Console.WriteLine("在Access數據庫中插入一條Department數據");
        }
    }

//用於操縱Sql Server中的Department表
class SqlserverDepartment : IDepartment
    {
        public Department GetDepartment(int id)
        {
            Console.WriteLine("在SqlServer中根據id獲取部門");
            return null;
        }

        public void Insert(Department department)
        {
            Console.WriteLine("在SqlServer中插入一條department數據");
        }
    }

using System.Reflection;
using System.Configuration;
//反射
	class DataAccess
    {
        private static readonly string AssemblyName = "Test";
        private static readonly string db = ConfigurationSettings.AppSettings["DB"];

        public static IUser CreateUser()
        {
            string className = AssemblyName + "." + db + "User";
            return (IUser)Assembly.Load(AssemblyName).CreateInstance(className);
        }

        public static IDepartment CreateDepartment()
        {
            string className = AssemblyName + "." + db + "Department";
            return (IDepartment)Assembly.Load(AssemblyName).CreateInstance(className);
        }

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
    </startup>
    <appSettings>
        <add key="DB" value="Access"/>
    </appSettings>
</configuration>

class Program
    {
        static void Main(string[] args)
        {
            //新數據
            User user = new User();
            Department department = new Department();
            
            IUser u = DataAccess.CreateUser();
            u.Insert(user);
            u.GetUser(1);

            IDepartment d = DataAccess.CreateDepartment();
            d.Insert(department);
            d.GetDepartment(1);
       }
   }