23种设计模式 UML 类图及对应示例代码 (二)

11.DoFactory.GangOfFour.Flyweight.Structural

Code
using System;
using System.Collections;

namespace DoFactory.GangOfFour.Flyweight.Structural
{
    /// <summary>
    /// MainApp startup class for Structural 
    /// Flyweight Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            // Arbitrary extrinsic state
            int extrinsicstate = 22;
        
            FlyweightFactory factory = new FlyweightFactory();

            // Work with different flyweight instances
            Flyweight fx = factory.GetFlyweight("X");
            fx.Operation(--extrinsicstate);

            Flyweight fy = factory.GetFlyweight("Y");
            fy.Operation(--extrinsicstate);

            Flyweight fz = factory.GetFlyweight("Z");
            fz.Operation(--extrinsicstate);

            UnsharedConcreteFlyweight fu = new 
                UnsharedConcreteFlyweight();

            fu.Operation(--extrinsicstate);

            // Wait for user
            Console.Read();
        }
    }

    // "FlyweightFactory" 

    class FlyweightFactory 
    {
        private Hashtable flyweights = new Hashtable();

        // Constructor
        public FlyweightFactory()
        {
            flyweights.Add("X", new ConcreteFlyweight());        
            flyweights.Add("Y", new ConcreteFlyweight());
            flyweights.Add("Z", new ConcreteFlyweight());
        }

        public Flyweight GetFlyweight(string key)
        {
            return((Flyweight)flyweights[key]); 
        }
    }

    // "Flyweight" 

    abstract class Flyweight 
    {
        public abstract void Operation(int extrinsicstate);
    }

    // "ConcreteFlyweight" 

    class ConcreteFlyweight : Flyweight
    {
        public override void Operation(int extrinsicstate)
        {
            Console.WriteLine("ConcreteFlyweight: " + extrinsicstate);
        }
    }

    // "UnsharedConcreteFlyweight" 

    class UnsharedConcreteFlyweight : Flyweight
    {
        public override void Operation(int extrinsicstate)
        {
            Console.WriteLine("UnsharedConcreteFlyweight: " + 
                extrinsicstate);
        }
    }
}

12.DoFactory.GangOfFour.Interpreter.Structural

Code
using System;
using System.Collections;

namespace DoFactory.GangOfFour.Interpreter.Structural
{
    /// <summary>
    /// MainApp startup class for Structural 
    /// Interpreter Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            Context context = new Context();

            // Usually a tree 
            ArrayList list = new ArrayList(); 

            // Populate 'abstract syntax tree' 
            list.Add(new TerminalExpression());
            list.Add(new NonterminalExpression());
            list.Add(new TerminalExpression());
            list.Add(new TerminalExpression());

            // Interpret
            foreach (AbstractExpression exp in list)
            {
                exp.Interpret(context);
            }

            // Wait for user
            Console.Read();
        }
    }

    // "Context" 

    class Context 
    {
    }

    // "AbstractExpression"

    abstract class AbstractExpression 
    {
        public abstract void Interpret(Context context);
    }

    // "TerminalExpression" 

    class TerminalExpression : AbstractExpression
    {
        public override void Interpret(Context context)    
        {
            Console.WriteLine("Called Terminal.Interpret()");
        }
    }

    // "NonterminalExpression" 

    class NonterminalExpression : AbstractExpression
    {
        public override void Interpret(Context context)    
        {
            Console.WriteLine("Called Nonterminal.Interpret()");
        }    
    }
}

13.DoFactory.GangOfFour.Iterator.Structural

Code
using System;
using System.Collections;

namespace DoFactory.GangOfFour.Iterator.Structural
{
    /// <summary>
    /// MainApp startup class for Structural 
    /// Iterator Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            ConcreteAggregate a = new ConcreteAggregate();
            a[0] = "Item A";
            a[1] = "Item B";
            a[2] = "Item C";
            a[3] = "Item D";

            // Create Iterator and provide aggregate
            ConcreteIterator i = new ConcreteIterator(a);

            Console.WriteLine("Iterating over collection:");
            
            object item = i.First();
            while (item != null)
            {
                Console.WriteLine(item);
                item = i.Next();
            } 

            // Wait for user
            Console.Read();
        }
    }

    // "Aggregate" 

    abstract class Aggregate
    {
        public abstract Iterator CreateIterator();
    }

    // "ConcreteAggregate" 

    class ConcreteAggregate : Aggregate
    {
        private ArrayList items = new ArrayList();

        public override Iterator CreateIterator()
        {
            return new ConcreteIterator(this);
        }

        // Property
        public int Count
        {
            get{ return items.Count; }
        }

        // Indexer
        public object this[int index]
        {
            get{ return items[index]; }
            set{ items.Insert(index, value); }
        }
    }

    // "Iterator"

    abstract class Iterator
    {
        public abstract object First();
        public abstract object Next();
        public abstract bool IsDone();
        public abstract object CurrentItem();
    }

    // "ConcreteIterator" 

    class ConcreteIterator : Iterator
    {
        private ConcreteAggregate aggregate;
        private int current = 0;

        // Constructor
        public ConcreteIterator(ConcreteAggregate aggregate)
        {
            this.aggregate = aggregate;
        }

        public override object First()
        {
            return aggregate[0];
        }

        public override object Next()
        {
            object ret = null;
            if (current < aggregate.Count - 1)
            {
                ret = aggregate[++current];
            }
            
            return ret;
        }

        public override object CurrentItem()
        {
            return aggregate[current];
        }

        public override bool IsDone()
        {
            return current >= aggregate.Count ? true : false ;
        }
    }
}

14.DoFactory.GangOfFour.Mediator.Structural

Code
using System;
using System.Collections;

namespace DoFactory.GangOfFour.Mediator.Structural
{
    /// <summary>
    /// MainApp startup class for Structural 
    /// Mediator Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            ConcreteMediator m = new ConcreteMediator();

            ConcreteColleague1 c1 = new ConcreteColleague1(m);
            ConcreteColleague2 c2 = new ConcreteColleague2(m);

            m.Colleague1 = c1;
            m.Colleague2 = c2;

            c1.Send("How are you?");
            c2.Send("Fine, thanks");

            // Wait for user
            Console.Read();
        }
    }

    // "Mediator" 

    abstract class Mediator
    {
        public abstract void Send(string message, 
            Colleague colleague);
    }

    // "ConcreteMediator" 

    class ConcreteMediator : Mediator
    {
        private ConcreteColleague1 colleague1;
        private ConcreteColleague2 colleague2;

        public ConcreteColleague1 Colleague1
        {
            set{ colleague1 = value; }
        }

        public ConcreteColleague2 Colleague2
        {
            set{ colleague2 = value; }
        }

        public override void Send(string message, 
            Colleague colleague)
        {
            if (colleague == colleague1)
            {
                colleague2.Notify(message);
            }
            else
            {
                colleague1.Notify(message);
            }
        }
    }

    // "Colleague" 

    abstract class Colleague
    {
        protected Mediator mediator;

        // Constructor
        public Colleague(Mediator mediator)
        {
            this.mediator = mediator;
        }
    }

    // "ConcreteColleague1" 

    class ConcreteColleague1 : Colleague
    {
        // Constructor
        public ConcreteColleague1(Mediator mediator) 
            : base(mediator) 
        { 
        }

        public void Send(string message)
        {
            mediator.Send(message, this);
        }

        public void Notify(string message)
        {
            Console.WriteLine("Colleague1 gets message: " 
                + message);
        }
    }

    // "ConcreteColleague2" 

    class ConcreteColleague2 : Colleague
    {
        // Constructor
        public ConcreteColleague2(Mediator mediator) 
            : base(mediator) 
        { 
        }
  
        public void Send(string message)
        {
            mediator.Send(message, this);
        }

        public void Notify(string message)
        {
            Console.WriteLine("Colleague2 gets message: " 
                + message);
        }
    }
}

15.DoFactory.GangOfFour.Memento.Structural

Code
using System;

namespace DoFactory.GangOfFour.Memento.Structural
{
    /// <summary>
    /// MainApp startup class for Structural 
    /// Memento Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            Originator o = new Originator();
            o.State = "On";

            // Store internal state
            Caretaker c = new Caretaker();
            c.Memento = o.CreateMemento();

            // Continue changing originator
            o.State = "Off";

            // Restore saved state
            o.SetMemento(c.Memento);

            // Wait for user
            Console.Read();
        }
    }

    // "Originator" 

    class Originator
    {
        private string state;

        // Property
        public string State
        {
            get{ return state; }
            set
            { 
                state = value; 
                Console.WriteLine("State = " + state);
            }
        }

        public Memento CreateMemento()
        {
            return (new Memento(state));
        }

        public void SetMemento(Memento memento)
        {
            Console.WriteLine("Restoring state");
            State = memento.State;
        }
    }

    // "Memento"

    class Memento
    {
        private string state;

        // Constructor
        public Memento(string state)
        {
            this.state = state;
        }

        // Property
        public string State
        {
            get{ return state; }
        }
    }

    // "Caretaker" 

    class Caretaker
    {
        private Memento memento;

        // Property
        public Memento Memento
        {
            set{ memento = value; }
            get{ return memento; }
        }
    }
}

16.DoFactory.GangOfFour.Observer.Structural

Code
using System;
using System.Collections;

namespace DoFactory.GangOfFour.Observer.Structural
{
    /// <summary>
    /// MainApp startup class for Structural 
    /// Observer Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            // Configure Observer pattern
            ConcreteSubject s = new ConcreteSubject();

            s.Attach(new ConcreteObserver(s,"X"));
            s.Attach(new ConcreteObserver(s,"Y"));
            s.Attach(new ConcreteObserver(s,"Z"));

            // Change subject and notify observers
            s.SubjectState = "ABC";
            s.Notify();

            // Wait for user
            Console.Read();
        }
    }

    // "Subject" 

    abstract class Subject
    {
        private ArrayList observers = new ArrayList();

        public void Attach(Observer observer)
        {
            observers.Add(observer);
        }

        public void Detach(Observer observer)
        {
            observers.Remove(observer);
        }

        public void Notify()
        {
            foreach (Observer o in observers)
            {
                o.Update();
            }
        }
    }

    // "ConcreteSubject" 

    class ConcreteSubject : Subject
    {
        private string subjectState;

        // Property
        public string SubjectState
        {
            get{ return subjectState; }
            set{ subjectState = value; }
        }
    }

    // "Observer" 

    abstract class Observer
    {
        public abstract void Update();
    }

    // "ConcreteObserver" 

    class ConcreteObserver : Observer
    {
        private string name;
        private string observerState;
        private ConcreteSubject subject;

        // Constructor
        public ConcreteObserver(
            ConcreteSubject subject, string name)
        {
            this.subject = subject;
            this.name = name;
        }

        public override void Update()
        {
            observerState = subject.SubjectState;
            Console.WriteLine("Observer {0}'s new state is {1}",
                name, observerState);
        }

        // Property
        public ConcreteSubject Subject
        {
            get { return subject; }
            set { subject = value; }
        }
    }
}

17.DoFactory.GangOfFour.Prototype.Structural

Code
using System;

namespace DoFactory.GangOfFour.Prototype.Structural
{
    /// <summary>
    /// MainApp startup class for Structural
    /// Prototype Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            // Create two instances and clone each

            ConcretePrototype1 p1 = new ConcretePrototype1("I");
            ConcretePrototype1 c1 = (ConcretePrototype1)p1.Clone();
            Console.WriteLine ("Cloned: {0}", c1.Id);

            ConcretePrototype2 p2 = new ConcretePrototype2("II");
            ConcretePrototype2 c2 = (ConcretePrototype2)p2.Clone();
            Console.WriteLine ("Cloned: {0}", c2.Id);

            // Wait for user
            Console.Read();
        }
    }

    // "Prototype" 

    abstract class Prototype
    {
        private string id;

        // Constructor
        public Prototype(string id)
        {
            this.id = id;
        }

        // Property
        public string Id
        {
            get{ return id; }
        }

        public abstract Prototype Clone();
    }

    // "ConcretePrototype1"

    class ConcretePrototype1 : Prototype
    {
        // Constructor
        public ConcretePrototype1(string id) : base(id) 
        {
        }

        public override Prototype Clone()
        {
            // Shallow copy
            return (Prototype)this.MemberwiseClone();
        }
    }

    // "ConcretePrototype2"

    class ConcretePrototype2 : Prototype
    {
        // Constructor
        public ConcretePrototype2(string id) : base(id) 
        {
        }

        public override Prototype Clone()
        {
            // Shallow copy
            return (Prototype)this.MemberwiseClone();
        }
    }
}

18.DoFactory.GangOfFour.Proxy.Structural

Code
using System;

namespace DoFactory.GangOfFour.Proxy.Structural
{
    /// <summary>
    /// MainApp startup class for Structural
    /// Proxy Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            // Create proxy and request a service
            Proxy proxy = new Proxy();
            proxy.Request();

            // Wait for user
            Console.Read();
        }
    }

    // "Subject" 

    abstract class Subject 
    {
        public abstract void Request();        
    }

    // "RealSubject" 

    class RealSubject : Subject
    {
        public override void Request()
        {
            Console.WriteLine("Called RealSubject.Request()");
        }
    }

    // "Proxy" 

    class Proxy : Subject
    {
        RealSubject realSubject;

        public override void Request()
        {
            // Use 'lazy initialization'
            if (realSubject == null)
            {
                realSubject = new RealSubject();
            }

            realSubject.Request();
        }    
    }
}

19.DoFactory.GangOfFour.Singleton.Structural

Code
using System;

namespace DoFactory.GangOfFour.Singleton.Structural
{
    /// <summary>
    /// MainApp startup class for Structural
    /// Singleton Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            // Constructor is protected -- cannot use new
            Singleton s1 = Singleton.Instance();
            Singleton s2 = Singleton.Instance();

            if (s1 == s2)
            {
                Console.WriteLine("Objects are the same instance");
            }

            // Wait for user
            Console.Read();
        }
    }

    // "Singleton"

    class Singleton
    {
        private static Singleton instance;

        // Note: Constructor is 'protected'
        protected Singleton() 
        {
        }

        public static Singleton Instance()
        {
            // Uses lazy initialization
            if (instance == null)
            {
                instance = new Singleton();
            }

            return instance;
        }
    }
}

20.DoFactory.GangOfFour.State.Structural

Code
using System;

namespace DoFactory.GangOfFour.State.Structural
{
    /// <summary>
    /// MainApp startup class for Structural
    /// State Design Pattern.
    /// </summary>
    class MainApp
    {
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        static void Main()
        {
            // Setup context in a state
            Context c = new Context(new ConcreteStateA());

            // Issue requests, which toggles state
            c.Request();
            c.Request();
            c.Request();
            c.Request();

            // Wait for user
            Console.Read();
        }
    }

    // "State" 

    abstract class State
    {
        public abstract void Handle(Context context);
    }

    // "ConcreteStateA"

    class ConcreteStateA : State
    {
        public override void Handle(Context context)
        {
            context.State = new ConcreteStateB();
        }
    }

    // "ConcreteStateB" 

    class ConcreteStateB : State
    {
        public override void Handle(Context context)
        {
            context.State = new ConcreteStateA();
        }
    }

    // "Context" 

    class Context
    {
        private State state;

        // Constructor
        public Context(State state)
        {
            this.State = state;
        }

        // Property
        public State State
        {
            get{ return state; }
            set
            { 
                state = value; 
                Console.WriteLine("State: " + 
                    state.GetType().Name);
            }
        }

        public void Request()
        {
            state.Handle(this);
        }
    }
}