23种设计模式学习一（单列模式）singleton

单列模式的类
    class Singleton
    {
        private static Singleton instance;
        private Singleton() { }
        public static Singleton Instance
        {
            get
            {
                if (instance == null)
                {
                    instance = new Singleton();
                }
                return instance;
            }
        }
    }

  Singleton demo = Singleton.Instance;
            Singleton demo2 = Singleton.Instance;
            Console.Write(object.ReferenceEquals(demo,demo2));
            Console.Read();