桥接模式（Bridge）

1.    定义

      将抽象部分与它的实现部分分离，使它们都可以独立变化。

2.      UML 类图

 

3.      结构代码

// Bridge pattern -- Structural example

using System;   namespace DoFactory.GangOfFour.Bridge.Structural {   /// <summary>   /// MainApp startup class for Structural   /// Bridge Design Pattern.   /// </summary>   class MainApp   {     /// <summary>     /// Entry point into console application.     /// </summary>     static void Main()     {       Abstraction ab = new RefinedAbstraction();         // Set implementation and call       ab.Implementor = new ConcreteImplementorA();       ab.Operation();         // Change implemention and call       ab.Implementor = new ConcreteImplementorB();       ab.Operation();         // Wait for user       Console.ReadKey();     }   }     /// <summary>   /// The 'Abstraction' class   /// </summary>   class Abstraction   {     protected Implementor implementor;       // Property     public Implementor Implementor     {       set { implementor = value; }     }       public virtual void Operation()     {       implementor.Operation();     }   }     /// <summary>   /// The 'Implementor' abstract class   /// </summary>   abstract class Implementor   {     public abstract void Operation();   }     /// <summary>   /// The 'RefinedAbstraction' class   /// </summary>   class RefinedAbstraction : Abstraction   {     public override void Operation()     {       implementor.Operation();     }   }     /// <summary>   /// The 'ConcreteImplementorA' class   /// </summary>   class ConcreteImplementorA : Implementor   {     public override void Operation()     {       Console.WriteLine("ConcreteImplementorA Operation");     }   }     /// <summary>   /// The 'ConcreteImplementorB' class   /// </summary>   class ConcreteImplementorB : Implementor   {     public override void Operation()     {       Console.WriteLine("ConcreteImplementorB Operation");     }   } }

Output ConcreteImplementorA Operation ConcreteImplementorB Operation

4.      实例代码

// Bridge pattern -- Real World example

using System; using System.Collections.Generic;   namespace DoFactory.GangOfFour.Bridge.RealWorld {   /// <summary>   /// MainApp startup class for Real-World   /// Bridge Design Pattern.   /// </summary>   class MainApp   {     /// <summary>     /// Entry point into console application.     /// </summary>     static void Main()     {       // Create RefinedAbstraction       Customers customers = new Customers("Chicago");         // Set ConcreteImplementor       customers.Data = new CustomersData();         // Exercise the bridge       customers.Show();       customers.Next();       customers.Show();       customers.Next();       customers.Show();       customers.Add("Henry Velasquez");         customers.ShowAll();         // Wait for user       Console.ReadKey();     }   }     /// <summary>   /// The 'Abstraction' class   /// </summary>   class CustomersBase   {     private DataObject _dataObject;     protected string group;       public CustomersBase(string group)     {       this.group = group;     }       // Property     public DataObject Data     {       set { _dataObject = value; }       get { return _dataObject; }     }       public virtual void Next()     {       _dataObject.NextRecord();     }       public virtual void Prior()     {       _dataObject.PriorRecord();     }       public virtual void Add(string customer)     {       _dataObject.AddRecord(customer);     }       public virtual void Delete(string customer)     {       _dataObject.DeleteRecord(customer);     }       public virtual void Show()     {       _dataObject.ShowRecord();     }       public virtual void ShowAll()     {       Console.WriteLine("Customer Group: " + group);       _dataObject.ShowAllRecords();     }   }     /// <summary>   /// The 'RefinedAbstraction' class   /// </summary>   class Customers : CustomersBase   {     // Constructor     public Customers(string group)       : base(group)     {     }       public override void ShowAll()     {       // Add separator lines       Console.WriteLine();       Console.WriteLine("------------------------");       base.ShowAll();       Console.WriteLine("------------------------");     }   }     /// <summary>   /// The 'Implementor' abstract class   /// </summary>   abstract class DataObject   {     public abstract void NextRecord();     public abstract void PriorRecord();     public abstract void AddRecord(string name);     public abstract void DeleteRecord(string name);     public abstract void ShowRecord();     public abstract void ShowAllRecords();   }     /// <summary>   /// The 'ConcreteImplementor' class   /// </summary>   class CustomersData : DataObject   {     private List<string> _customers = new List<string>();     private int _current = 0;       public CustomersData()     {       // Loaded from a database       _customers.Add("Jim Jones");       _customers.Add("Samual Jackson");       _customers.Add("Allen Good");       _customers.Add("Ann Stills");       _customers.Add("Lisa Giolani");     }       public override void NextRecord()     {       if (_current <= _customers.Count - 1)       {         _current++;       }     }       public override void PriorRecord()     {       if (_current > 0)       {         _current--;       }     }       public override void AddRecord(string customer)     {       _customers.Add(customer);     }       public override void DeleteRecord(string customer)     {       _customers.Remove(customer);     }       public override void ShowRecord()     {       Console.WriteLine(_customers[_current]);     }       public override void ShowAllRecords()     {       foreach (string customer in _customers)       {         Console.WriteLine(" " + customer);       }     }   } }

Output Jim Jones Samual Jackson Allen Good ------------------------ Customer Group: Chicago Jim Jones Samual Jackson Allen Good Ann Stills Lisa Giolani Henry Velasquez ------------------------

该文章来自：http://www.dofactory.com/Patterns/PatternBridge.aspx