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js抽象工厂模式
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。
抽象工厂允许客户使用抽象的接口来创建一组相关产品,而不需要知道或关心实际生产出的具体产品是什么。这样客户就可以从具体产品中被解耦。下面通过抽象工模式的类图来了解各个类中之间的关系:
抽象工厂的分析
抽象工厂模式将具体产品的创建延迟到具体工厂的子类中,这样将对象的创建封装起来,可以减少客户端与具体产品类之间的依赖,从而使系统耦合度低,这 样更有利于后期的维护和扩展,这真是抽象工厂模式的优点所在,然后抽象模式同时也存在不足的地方。下面就具体看下抽象工厂的缺点(缺点其实在前面的介绍中 以已经涉及了):
抽象工厂模式很难支持新种类产品的变化。这是因为抽象工厂接口中已经确定了可以被创建的产品集合,如果需要添加新产品,此时就必须去修改抽象工厂的接口,这样就涉及到抽象工厂类的以及所有子类的改变,这样也就违背了“开发——封闭”原则。
知道了抽象工厂的优缺点之后,也就能很好地把握什么情况下考虑使用抽象工厂模式了,下面就具体看看使用抽象工厂模式的系统应该符合那几个前提:
- 一个系统不要求依赖产品类实例如何被创建、组合和表达的表达,这点也是所有工厂模式应用的前提。
- 这个系统有多个系列产品,而系统中只消费其中某一系列产品
- 系统要求提供一个产品类的库,所有产品以同样的接口出现,客户端不需要依赖具体实现。
C#抽象工厂-多数据库:
namespace 抽象工厂多数据库 { class Program { static void Main(string[] args) { User user = new User(); Department dept = new Department(); //AbstractFactory factory = new SqlServerFactory(); IFactory factory = new AccessFactory(); IUser iu = factory.CreateUser(); iu.Insert(user); iu.GetUser(1); IDepartment id = factory.CreateDepartment(); id.Insert(dept); id.GetDepartment(1); 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(); } } }
C#抽象工厂-用简单工厂来改进:
namespace 抽象工厂用简单工厂来改进 { class Program { static void Main(string[] args) { User user = new User(); Department dept = new Department(); IUser iu = DataAccess.CreateUser(); iu.Insert(user); iu.GetUser(1); IDepartment id = DataAccess.CreateDepartment(); id.Insert(dept); id.GetDepartment(1); 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 = "抽象工厂用简单工厂来改进"; 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); } } }
js抽象工厂模式
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