c#设计模式之单例

using System;namespace Program{    class SingleThread_Singleton    {        private static SingleThread_Singleton instance = null;        private SingleThread_Singleton() { }        public static SingleThread_Singleton Instance        {            get            {                if (null == instance)                {                    instance = new SingleThread_Singleton();                }                return instance;            }        }    }    class Program    {        public static void Main()        {            SingleThread_Singleton a = SingleThread_Singleton.Instance;            SingleThread_Singleton b = SingleThread_Singleton.Instance;            Console.ReadKey();        }    }}