使用Interface和Dictionary

interface实现polymopherson

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using TryCollection.Abstract;

namespace TryCollection
{
    class Engine
    {
        private IState _state;
        public IState State
        {
            get { return _state; }
            set { _state = value; }
        }
        public void Run(IState initialState)
        {
            _state = initialState;
            while (true)
            {
                _state.Render();
                var command = _state.GetCommand();
                command.Execute();
            }
        }
    }
}

dictionary实现key与value的配对

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using TryCollection.Abstract;
using System.Collections;
using TryCollection.States;
using TryCollection.Commands;
using TryCollection;

namespace TryCollection.States
{
    class MainMenuState : IState
    {
        private Engine _engine;   
        private Dictionary<string, IState> _menuDictionary;
        private ICommand _continueCommand;
        private ICommand _helpCommand;
        private IState _continueMenu;
        private IState _helpMenu;
        public MainMenuState(Engine engine)
        {
            _engine = engine;
            _continueMenu = new ContinueMenu(_engine, this);
            _helpMenu = this;

            _menuDictionary = new Dictionary<string, IState> //制作dictionary，使输入与对应的menu匹配
            {
                { "con", _continueMenu },
                { "help", _helpMenu } 
            };
        }

        public void Render()
        {
            
            Console.WriteLine("[con] - Continue");
            Console.WriteLine("[Help] - Help\n");
        }

        public ICommand GetCommand()
        {
            var inputString = Console.ReadLine();
            //
            foreach (var commandMenuPair in _menuDictionary)    
            {
                if (commandMenuPair.Key == inputString) //这是Dictionary用的最巧妙的地方，不需要很多if else判断
                {
                    _engine.State = commandMenuPair.Value;  
                    ICommand command = ConvertCommand(inputString);
                    return command;
                }
            }
                 return new InvalidCommand();
        }
        ICommand ConvertCommand(string commandString)
        {
            if (commandString == "con")
            {
                return new ContinueCommand();
            }
            else
            {
                return new HelpCommand();
            }
        }


    }
}

Dictionary与IDictionary的区别。IDictionary例子：public IDictionary IMan<IShawn,IChris>, IShawn:IMan   IChris:IMan,他们有同样的Iman方法