[学习笔记]工厂方法用于数据库开发

摘自《大话设计模式》一书。

程序入口：

 1 using System;  2 using System.Collections.Generic;  3 using System.Text;  4 using System.Reflection;  5 using System.Configuration;  6 

 7 namespace 抽象工厂模式  8 {  9     class Program 10  { 11         static void Main(string[] args) 12  { 13             User user = new User(); 14             Department dept = new Department(); 15 

16             IUser iu = DataAccess.CreateUser(); 17 

18  iu.Insert(user); 19             iu.GetUser(1); 20 

21             IDepartment id = DataAccess.CreateDepartment(); 22  id.Insert(dept); 23             id.GetDepartment(1); 24 

25  Console.Read(); 26  } 27  } 28 }

Main

工厂方法：

 1 class DataAccess  2  {  3         private static readonly string AssemblyName = "抽象工厂模式";  4         private static readonly string db = ConfigurationManager.AppSettings["DB"];  5         

 6         public static IUser CreateUser()  7  {  8             string className = AssemblyName + "." + db + "User";  9             return (IUser)Assembly.Load(AssemblyName).CreateInstance(className); 10  } 11 

12         public static IDepartment CreateDepartment() 13  { 14             string className = AssemblyName + "." + db + "Department"; 15             return (IDepartment)Assembly.Load(AssemblyName).CreateInstance(className); 16  } 17     }

 数据实体类User和Department：

 1    class User  2  {  3         private int _id;  4         public int ID  5  {  6             get { return _id; }  7             set { _id = value; }  8  }  9 

10         private string _name; 11         public string Name 12  { 13             get { return _name; } 14             set { _name = value; } 15  } 16     }

 1  class Department  2  {  3         private int _id;  4         public int ID  5  {  6             get { return _id; }  7             set { _id = value; }  8  }  9 

10         private string _deptName; 11         public string DeptName 12  { 13             get { return _deptName; } 14             set { _deptName = value; } 15  } 16     }

 数据操作：

1   interface IUser 2  { 3         void Insert(User user); 4 

5         User GetUser(int id); 6     }

 1   class SqlserverUser : IUser  2  {  3         public void Insert(User user)  4  {  5             Console.WriteLine("在Sqlserver中给User表增加一条记录");  6  }  7 

 8         public User GetUser(int id)  9  { 10             Console.WriteLine("在Sqlserver中根据ID得到User表一条记录"); 11             return null; 12  } 13     }

SqlserverUser : IUser

 1  class AccessUser : IUser  2  {  3         public void Insert(User user)  4  {  5             Console.WriteLine("在Access中给User表增加一条记录");  6  }  7 

 8         public User GetUser(int id)  9  { 10             Console.WriteLine("在Access中根据ID得到User表一条记录"); 11             return null; 12  } 13     }

AccessUser : IUser

1  interface IDepartment 2  { 3         void Insert(Department department); 4 

5         Department GetDepartment(int id); 6     }

 1  class SqlserverDepartment : IDepartment  2  {  3         public void Insert(Department department)  4  {  5             Console.WriteLine("在Sqlserver中给Department表增加一条记录");  6  }  7 

 8         public Department GetDepartment(int id)  9  { 10             Console.WriteLine("在Sqlserver中根据ID得到Department表一条记录"); 11             return null; 12  } 13     }

SqlserverDepartment : IDepartment

 1  class AccessDepartment : IDepartment  2  {  3         public void Insert(Department department)  4  {  5             Console.WriteLine("在Access中给Department表增加一条记录");  6  }  7 

 8         public Department GetDepartment(int id)  9  { 10             Console.WriteLine("在Access中根据ID得到Department表一条记录"); 11             return null; 12  } 13     }

AccessDepartment : IDepartment

 以前总是把IUser接口这样的操作也写到数据库视图中，老是感觉不和谐。从抽象的角度看，数据库操作并不是实体User的必须方法，而且我也不是什么时候都需要调用数据的，如果把实体中增加了数据库操作方法，调用者恶意调用多麻烦！这里再分一个抽象的IUser专门管理数据库操作还是很好的。