单例类助手（代码）

 /// <summary>
    /// 单例类助手
    /// </summary>   
    public sealed class SingletonHelper<T> where T : new()
    {
        private static T instance = new T();

        private static object locker = new object();

        private SingletonHelper() { }

        /// <summary>
        /// 获取单例
        /// </summary>
        /// <returns></returns>
        public static T GetInstance()
        {
            if (null == instance)
            {
                lock (locker)
                {
                    if (null == instance)
                    {
                        instance = new T();
                    }
                }
            }
            return instance;
        }

        /// <summary>
        /// 设置单例
        /// </summary>
        /// <param name="value"></param>
        public void SetInstance(T value)
        {
            instance = value;
        }
    }