就不能换DB吗？ 抽象工厂模式
2024-09-06 17:54:02
15.1 就不能换DB吗？
15.2 最基本的数据访问程序
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
User user = new User(); SqlserverUser su = new SqlserverUser(); //与SQLServer耦合， su.Insert(user);
su.GetUser(); Console.Read();
}
} //用户类，
class User
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _name; public string Name
{
get { return _name; }
set { _name = value; }
}
} //操作User表类，
class SqlserverUser
{
//新增用户，
public void Insert(User user)
{
Console.WriteLine("在Sqlserver中给User表增加一条记录");
} //得到用户，
public User GetUser(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到User表一条记录");
return null;
}
} }
15.3 用了工厂方法模式的数据访问程序
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
User user = new User(); //IFactory factory = new SqlServerFactory();
IFactory factory = new AccessFactory(); IUser iu = factory.CreateUser(); iu.Insert(user);
iu.GetUser(); Console.Read();
}
} class User
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _name; public string Name
{
get { return _name; }
set { _name = value; }
}
} //IUser接口，用于客户端访问，解除与具体数据库的耦合，
interface IUser
{
void Insert(User user); User GetUser(int id);
} //SqlserverUser类，用于访问SQLServer的User，
class SqlserverUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Sqlserver中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到User表一条记录");
return null;
}
} //AccessUser类，用于访问Access的User，
class AccessUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Access中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Access中根据ID得到User表一条记录");
return null;
}
} //IFactory接口，定义一个创建访问User表对象的抽象的工厂接口，
interface IFactory
{
IUser CreateUser();
} //SqlServerFactory类，实现IFactory接口，实例化SqlserverUser，
class SqlServerFactory : IFactory
{
public IUser CreateUser()
{
return new SqlserverUser();
}
} //AccessFactory类，实现IFactory接口，实例化AccessUser，
class AccessFactory : IFactory
{
public IUser CreateUser()
{
return new AccessUser();
}
} }
15.4 用了抽象工厂模式的数据访问程序
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
User user = new User();
Department dept = new Department(); //IFactory factory = new SqlServerFactory();
IFactory factory = new AccessFactory(); IUser iu = factory.CreateUser();
iu.Insert(user);
iu.GetUser(); IDepartment id = factory.CreateDepartment();
id.Insert(dept);
id.GetDepartment(); Console.Read();
}
} class User
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _name; public string Name
{
get { return _name; }
set { _name = value; }
}
} class Department
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _deptName; public string DeptName
{
get { return _deptName; }
set { _deptName = value; }
}
} interface IUser
{
void Insert(User user); User GetUser(int id);
} class SqlserverUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Sqlserver中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到User表一条记录");
return null;
}
} class AccessUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Access中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Access中根据ID得到User表一条记录");
return null;
}
} interface IDepartment
{
void Insert(Department department); Department GetDepartment(int id);
} class SqlserverDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Sqlserver中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到Department表一条记录");
return null;
}
} class AccessDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Access中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Access中根据ID得到Department表一条记录");
return null;
}
} interface IFactory
{
IUser CreateUser(); IDepartment CreateDepartment();
} class SqlServerFactory : IFactory
{
public IUser CreateUser()
{
return new SqlserverUser();
} public IDepartment CreateDepartment()
{
return new SqlserverDepartment();
}
} class AccessFactory : IFactory
{
public IUser CreateUser()
{
return new AccessUser();
} public IDepartment CreateDepartment()
{
return new AccessDepartment();
}
} }
15.5 抽象工厂模式
提供一个创建一系列相关或相互依赖对象的接口，而无需指定它们具体的类，
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
AbstractFactory factory1 = new ConcreteFactory1();
Client c1 = new Client(factory1);
c1.Run(); AbstractFactory factory2 = new ConcreteFactory2();
Client c2 = new Client(factory2);
c2.Run(); Console.Read();
}
} //抽象产品A，
abstract class AbstractProductA
{
//它们可以有不同的实现，
} //抽象产品B，
abstract class AbstractProductB
{
public abstract void Interact(AbstractProductA a);
} //对两个抽象产品A和B的具体分类的实现，
class ProductA1 : AbstractProductA
{ } //对两个抽象产品A和B的具体分类的实现，
class ProductB1 : AbstractProductB
{
public override void Interact(AbstractProductA a)
{
Console.WriteLine(this.GetType().Name + " interacts with " + a.GetType().Name);
}
} //对两个抽象产品A和B的具体分类的实现，
class ProductA2 : AbstractProductA
{ } //对两个抽象产品A和B的具体分类的实现，
class ProductB2 : AbstractProductB
{
public override void Interact(AbstractProductA a)
{
Console.WriteLine(this.GetType().Name + " interacts with " + a.GetType().Name);
}
} //抽象工厂接口，包含所有产品创建的抽象方法，
abstract class AbstractFactory
{
public abstract AbstractProductA CreateProductA();
public abstract AbstractProductB CreateProductB();
} //具体工厂，
class ConcreteFactory1 : AbstractFactory
{
public override AbstractProductA CreateProductA()
{
return new ProductA1();
} public override AbstractProductB CreateProductB()
{
return new ProductB1();
}
} //具体工厂，
class ConcreteFactory2 : AbstractFactory
{
public override AbstractProductA CreateProductA() //运行时创建ConcreteFactory类的实例，具体的工厂再创建具有特定实现的产品对象，
{ //即创建不同的产品对象，客户端应使用不同的具体工厂，
return new ProductA2();
} public override AbstractProductB CreateProductB()
{
return new ProductB2();
}
} class Client
{
private AbstractProductA AbstractProductA;
private AbstractProductB AbstractProductB; public Client(AbstractFactory factory)
{
AbstractProductB = factory.CreateProductB();
AbstractProductA = factory.CreateProductA();
} public void Run()
{
AbstractProductB.Interact(AbstractProductA);
}
} }
15.6 抽象工厂模式的优点与缺点
优点：最大的好处便是易于交换产品系列，由于具体工厂类，在一个应用中只需要在初始化的时候出现一次，这就使得改变一个应用的具体工厂变得非常容易，它只需要改变具体工厂即可使用不同的产品配置，第二大好处是，它让具体的创建实例过程与客户端分离，客户端是通过它们的抽象接口操纵实例，产品的具体类名也被具体工厂的实现分离，不会出现在客户代码中，
缺点：抽象工厂模式可以很方便的切换两个数据库访问的代码，但如果你的需求来自增加功能，如增加项目表Project，需要改动哪些部分？至少增加三个类，IProject，SqlserverProject，AccessProject，需更改三个类，IFactory，SqlserverFactory，AccessFactory，并且客户端程序显然不会只有一个，如果有100个调用数据库访问的类，是不是要更改100次 IFactory factory = new AccessFactory( ); 这样的代码才行呢？这不能解决我要更改数据库时，改动一处就完全更改的要求阿，
15.7 用简单工厂来改进抽象工厂
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
User user = new User();
Department dept = new Department(); IUser iu = DataAccess.CreateUser();
iu.Insert(user);
iu.GetUser(); IDepartment id = DataAccess.CreateDepartment();
id.Insert(dept);
id.GetDepartment(); Console.Read();
}
} class User
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _name; public string Name
{
get { return _name; }
set { _name = value; }
}
} class Department
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _deptName; public string DeptName
{
get { return _deptName; }
set { _deptName = value; }
}
} interface IUser
{
void Insert(User user); User GetUser(int id);
} class SqlserverUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Sqlserver中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到User表一条记录");
return null;
}
} class AccessUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Access中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Access中根据ID得到User表一条记录");
return null;
}
} interface IDepartment
{
void Insert(Department department); Department GetDepartment(int id);
} class SqlserverDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Sqlserver中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到Department表一条记录");
return null;
}
} class AccessDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Access中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Access中根据ID得到Department表一条记录");
return null;
}
} class DataAccess
{
private static readonly string db = "Sqlserver"; //与其用IFactory，SqlserverFactory，AccessFactory三个工厂类，
//private static readonly string db = "Access"; //不如直接用一个简单工厂来实现，DataAccess类取而代之它们，
//客户端没有出现任何一个SQLServer或Access的字样，达到了解耦的目的，
public static IUser CreateUser() //客户端已经不在受改动数据库访问的影响了，
{ //但增加数据库访问就麻烦了，
IUser result = null;
switch (db)
{
case "Sqlserver":
result = new SqlserverUser();
break;
case "Access":
result = new AccessUser();
break;
}
return result;
} public static IDepartment CreateDepartment()
{
IDepartment result = null;
switch (db)
{
case "Sqlserver":
result = new SqlserverDepartment();
break;
case "Access":
result = new AccessDepartment();
break;
}
return result;
}
} }
15.8 用反射+抽象工厂的数据访问程序
Assembly.Load("程序集名称").CreateInstance("命名空间.类名称");
原来实例化是写死在程序里的，现在用了反射就可以利用字符串来实例化对象，而变量是可以更换的，即变量"db"，
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
User user = new User();
Department dept = new Department(); IUser iu = DataAccess.CreateUser();
iu.Insert(user);
iu.GetUser(); IDepartment id = DataAccess.CreateDepartment();
id.Insert(dept);
id.GetDepartment(); Console.Read();
}
} class User
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _name; public string Name
{
get { return _name; }
set { _name = value; }
}
} class Department
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _deptName; public string DeptName
{
get { return _deptName; }
set { _deptName = value; }
}
} interface IUser
{
void Insert(User user); User GetUser(int id);
} class SqlserverUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Sqlserver中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到User表一条记录");
return null;
}
} class AccessUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Access中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Access中根据ID得到User表一条记录");
return null;
}
} interface IDepartment
{
void Insert(Department department); Department GetDepartment(int id);
} class SqlserverDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Sqlserver中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到Department表一条记录");
return null;
}
} class AccessDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Access中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Access中根据ID得到Department表一条记录");
return null;
}
} class DataAccess
{
//程序集名称，
private static readonly string AssemblyName = "抽象工厂模式"; //数据库名称，
private static readonly string db = "Sqlserver";
//private static readonly string db = "Access"; public static IUser CreateUser()
{
string className = AssemblyName + "." + db + "User"; //此处是字符串，可以用变量来处理，也就可以根据需要更换，
return (IUser)Assembly.Load(AssemblyName).CreateInstance(className);
} public static IDepartment CreateDepartment()
{
string className = AssemblyName + "." + db + "Department";
return (IDepartment)Assembly.Load(AssemblyName).CreateInstance(className);
}
} }
15.9 用反射+配置文件的数据访问程序
namespace 抽象工厂模式
{
class Program
{
static void Main(string[] args)
{
User user = new User();
Department dept = new Department(); IUser iu = DataAccess.CreateUser();
iu.Insert(user);
iu.GetUser(); IDepartment id = DataAccess.CreateDepartment();
id.Insert(dept);
id.GetDepartment(); Console.Read();
}
} class User
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _name; public string Name
{
get { return _name; }
set { _name = value; }
}
} class Department
{
private int _id; public int ID
{
get { return _id; }
set { _id = value; }
} private string _deptName; public string DeptName
{
get { return _deptName; }
set { _deptName = value; }
}
} interface IUser
{
void Insert(User user); User GetUser(int id);
} class SqlserverUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Sqlserver中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到User表一条记录");
return null;
}
} class AccessUser : IUser
{
public void Insert(User user)
{
Console.WriteLine("在Access中给User表增加一条记录");
} public User GetUser(int id)
{
Console.WriteLine("在Access中根据ID得到User表一条记录");
return null;
}
} interface IDepartment
{
void Insert(Department department); Department GetDepartment(int id);
} class SqlserverDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Sqlserver中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Sqlserver中根据ID得到Department表一条记录");
return null;
}
} class AccessDepartment : IDepartment
{
public void Insert(Department department)
{
Console.WriteLine("在Access中给Department表增加一条记录");
} public Department GetDepartment(int id)
{
Console.WriteLine("在Access中根据ID得到Department表一条记录");
return null;
}
} class DataAccess
{
private static readonly string AssemblyName = "抽象工厂模式"; //读配置文件，
private static readonly string db = ConfigurationManager.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);
}
} }
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="DB" value="Access"/>
</appSettings>
</configuration>
15.10 无痴迷 不成功
最新文章
- Java初始化过程
- CentOS 7 上部署Mono 4 和Jexus 5.6
- redis安装记录
- mysql初级命令
- go http.Get请求 http.Post请求 http.PostForm请求 Client 超时设置
- mysql 行转列 和 列转行
- POJ 3349 HASH
- easyui datagrid将表头的checkbox不显示（隐藏）
- 【Android开发坑系列】之try-catch
- 第二周 PSP项目计划
- 【转】 CATransform3D 矩阵变换之立方体旋转实现细节
- [转] arcgis Engine创建shp图层
- 学习java随笔第九篇：java异常处理
- 运行从别处复制过来的linux可执行程序
- python 凸包(经纬度) ＋ 面积［近似］
- JAVA转让JS功能
- android studio gradle 打jar 包 （混淆＋第三方库包）
- 关于第一次在IDEA上使用lombok时注解完全不起作用
- 走进JVM之一 自己编译openjdk源码
- mysql 案例~mysql主从复制延迟处理(2)
热门文章
- linux下误清用户/home下的文件怎么办？
- HanLP《自然语言处理入门》笔记--2.词典分词
- springIOC源码接口分析(七):ApplicationEventPublisher
- selenium 调用JavaScript代码
- 导弹拦截（dp复习）
- Codeforces gym101755F Tree Restoration(拓扑排序)
- Comet OJ Contest #0 解方程(暴力)
- SpringBoot、Spring MVC报错：Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
- 某oa系统的审计
- 注销Apache