备忘录模式

/*
 *
 * User: Administrator
 * Date: 2007-7-2
 * Time: 9:02
  */
using  System;
using  System.Collections.Generic;

namespace  myMemonto
{

     public   interface  IMemonto{}

     public   class  State
    {
         public  State(){}
         public   string  stateName; // 状态名
         public   int  Level; // 状态级别
    }

     // 发起者
     public   class  Originator
    {
         private   class  Memonto:IMemonto
        {
             private  State _state;
             public  Memonto(State st)
            {
                _state = new  State();
                _state.stateName = st.stateName;
                _state.Level = st.Level;
            }
         public  State state
        {
             get {
                 return  _state;
            }
             set {
                _state = value;
            }
        }

        }




         private  State state;

         public  Originator()
        {
            state = new  State();
            state.stateName = " begin " ;
            state.Level = 1 ;
        }
         public   string  StateName
        {
             get { return  state.stateName;}
             set {state.stateName = value;}
        }
         public   int  Level
        {
             get
            {
                 return  state.Level;
            }
             set
            {
                state.Level = value;
            }
        }
         public  IMemonto CreateMomento()    {
             return   new  Memonto( this .state);
        }
         public   void  SetState(IMemonto m)
        {
            Memonto mm = (Memonto)m;
             this .state = mm.state;
        }

    }

     public   class  Caretaker:System.Collections.CollectionBase
    {
         public  Caretaker(){}
         public   int  Add(IMemonto st)
        {
             return  List.Add(st);
        }
         public  IMemonto  this [ int  index]{
             get {
                 return  (IMemonto)List[index];
            }

             set {
                List[index] = value;
            }
        }
         public   void  Remove(IMemonto st){
            List.Remove(st);
        }
         public  IMemonto Restore()
        {
             if (List.Count == 0 )  return   null ;
            IMemonto st = (IMemonto) List[List.Count - 1 ];
            List.Remove(st);
             return  st;
        }
    }



     class  MainClass
    {
         public   static   void  Main( string [] args)
        {
             // Console.WriteLine("Hello World!");
            Originator o = new  Originator();
            Caretaker c = new  Caretaker();
            c.Add(o.CreateMomento());

            o.StateName = " one " ;
            o.Level = 100 ;

            c.Add(o.CreateMomento());

            o.StateName = " two " ;
            o.Level = 200 ;

            c.Add(o.CreateMomento());

            IMemonto m = c.Restore();

             while (m != null ){
                o.SetState(m);
                System.Console.WriteLine(o.StateName);
                m = c.Restore();
            }
            System.Console.ReadLine();
        }
    }
}