JAVA高级面试进阶训练营视频教程

admin

        DateTime lastClick = DateTime.Now;
        object obj = new object();
        int i = 0;
        private  void Button_Click(object sender, RoutedEventArgs e)
        {
            this.IsEnabled = false;      
            var t = (DateTime.Now - lastClick).TotalMilliseconds;
            i++;
            lastClick = DateTime.Now;
            System.Diagnostics.Debug.Print(t + "," + i + ";" + DateTime.Now);
            Thread.Sleep(2000);         
            this.IsEnabled = true;
        }

以上代码并没法解决用户点击两次按钮触发两次的问题,因为ui线程是单线程的,所以这个这样会导致用户连续点击两次,会两秒后又调用Button_Click一次,输出如下:

1207.069,1;2017年4月19日 13:58:22
2055.1176,2;2017年4月19日 13:58:24

所以要在this.IsEnabled = false;后面强制界面刷新,代码如下:

   private  void Button_Click(object sender, RoutedEventArgs e)
        {
            this.IsEnabled = false;
            DispatcherHelper.DoEvents();
            var t = (DateTime.Now - lastClick).TotalMilliseconds;
            i++;
            lastClick = DateTime.Now;
            System.Diagnostics.Debug.Print(t + "," + i + ";" + DateTime.Now);
            Thread.Sleep(2000);         
            this.IsEnabled = true;
        }
        public static class DispatcherHelper
        {
            [SecurityPermissionAttribute(SecurityAction.Demand, Flags = SecurityPermissionFlag.UnmanagedCode)]
            public static void DoEvents()
            {
                DispatcherFrame frame = new DispatcherFrame();
                Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.Background, new DispatcherOperationCallback(ExitFrames), frame);
                try { Dispatcher.PushFrame(frame); }
                catch (InvalidOperationException) { }
            }
            private static object ExitFrames(object frame)
            {
                ((DispatcherFrame)frame).Continue = false;
                return null;
            }
        }

 DispatcherHelper.DoEvents();这个方法会强制界面刷新,问题就解决了