class1.cs

来自DoFactory的设计模式, 由于是本人根据已有代码创建,没有NETOptimized项

// State pattern -- Structural example  

using System;

namespace DoFactory.GangOfFour.State.Structural
{

    // MainApp test application 

    class MainApp
    {
        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);
        }
    }
}