C#单例模式

　　1.单例模式     

    public class Car
    {
        private static Car instance = null;
        private static object obj = new object();//锁
        private Car() { }//通过一个private禁止对Car进行实例化
        public static Car Instance//只能通过此进行实例化
        {
            get
            {
                if (instance == null)
                {
                    lock (obj)
                    {
                        if (instance == null)
                        {
                            instance = new Car();
                        }                  
                    }                   
                }
                return instance;
            }
        }
    }