Singleton 单例模式 泛型 窗体控制

MDI子窗体

控制单例

 /// <summary>
    /// 单例提供者
    /// </summary>
    /// <typeparam name="T">需要的类</typeparam>
    public class SingletonProvider<T> where T : System.Windows.Forms.Form, new()
    {
        private static T instance = default(T);
        private static readonly object obj = new object();

        /// <summary>
        /// 获取窗体的唯一实例
        /// </summary>
        public static T Instance
        {
            get
            {
                //双检锁（double-check locking）保证线程安全
                if (instance == null)
                {
                    lock (obj)
                    {
                        if (instance == null)
                        {
                            instance = new T();

                            //加上实例关闭事件，窗体就会自动回收，即instance=null；
                            instance.FormClosed += new System.Windows.Forms.FormClosedEventHandler(instance_FormClosed);
                        }
                    }
                }
                return instance;
            }
        }
        /// <summary>
        /// 当窗体关闭时将Instance置空
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        static void instance_FormClosed(object sender, System.Windows.Forms.FormClosedEventArgs e)
        {
            instance = default(T);
        }
    }