WPF中监听剪贴板存在的Bug：OpenClipboard HRESULT:0x800401D0 (CLIPBRD_E_CANT_OPEN))错误

1.WPF监听剪贴板的方法

WPF的方法和WinForm略有不同，具体步骤如下：

（1）首先定义消息钩子

        #region 消息钩子预定义参数
        private const int WM_DRAWCLIPBOARD = 0x308;
        private const int WM_CHANGECBCHAIN = 0x30D;

        private IntPtr mNextClipBoardViewerHWnd;

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static public extern IntPtr SetClipboardViewer(IntPtr hWndNewViewer);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static public extern bool ChangeClipboardChain(IntPtr HWnd, IntPtr HWndNext);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static public extern int SendMessage(IntPtr hWnd, int msg, int wParam, int lParam);
        #endregion

（2）重写OnSourceInitialized

        protected override void OnSourceInitialized(EventArgs e)
        {
            base.OnSourceInitialized(e);
            HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
            //挂消息钩子
            mNextClipBoardViewerHWnd = SetClipboardViewer(source.Handle);
            source.AddHook(WndProc);
        }

（3）处理消息WM_DRAWCLIPBOARD 和WM_CHANGECBCHAIN

        /// <summary>
        ///  参考：https://blog.csdn.net/xlm289348/article/details/8050957
        ///  MSG=0x308无法收到消息，原因是0x308是在剪贴板发生变化时将消息发送到监听列表中的第一个窗口
        ///  所有这里要收到0x308必须将窗口放到监听列表里
        ///  即在OnSourceInitialized(EventArgs e) 中调用SetClipboardView
        /// </summary>
        /// <param name="hwnd"></param>
        /// <param name="msg"></param>
        /// <param name="wParam"></param>
        /// <param name="lParam"></param>
        /// <param name="handled"></param>
        /// <returns></returns>
        IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            switch (msg)
            {
                case WM_DRAWCLIPBOARD:
                    {
                        SendMessage(mNextClipBoardViewerHWnd, msg, wParam.ToInt32(), lParam.ToInt32());
                        //文本内容检测
                        if (System.Windows.Clipboard.ContainsText())
                        {
                        	//System.Windows.Clipboard.GetText()此处有Bug
                            //String ct = System.Windows.Clipboard.GetText();
                            String ct = getClipboardText();                   
                          	//做进一步操作
                        }
                    }
                    break;
                case WM_CHANGECBCHAIN:
                    {
                        if (wParam == (IntPtr)mNextClipBoardViewerHWnd)
                        {
                            mNextClipBoardViewerHWnd = lParam;
                        }
                        else
                        {
                            SendMessage(mNextClipBoardViewerHWnd, msg, wParam.ToInt32(), lParam.ToInt32());
                        }
                    }
                    break;
                default:
                    break;
            }
            return IntPtr.Zero;
        }

（4）退出程序时注意移除钓子

        private void ModernWindow_Closing(object sender, EventArgs e)
        {
            HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
            //移除消息钩子
            ChangeClipboardChain(source.Handle, mNextClipBoardViewerHWnd);
            source.RemoveHook(WndProc);
        }

2.WPF在读取剪贴板内容时报OpenClipboard HRESULT:0x800401D0 (CLIPBRD_E_CANT_OPEN))错误

如果直接通过Clipboard.GetText()获取剪贴板上的文本时，如果剪贴板被占用（每次只能一个程序读取），则会报OpenClipboard HRESULT:0x800401D0 (CLIPBRD_E_CANT_OPEN))错误，这是个随机错误，所以比较隐蔽，而且在WinForm中没有这个问题。

网上搜到有三种方法，这里我就只把我的解决方法贴在这里，因为剪贴板被其它程序占用是个小概率事件且占用时间通常很短，每次读取时多试几次就可以了。

        private String getClipboardText()
        {
            for (int i = 0; i < 200; i++)
            {
                try
                {
                    return System.Windows.Clipboard.GetText();
                }
                catch
                {
                    System.Threading.Thread.Sleep(10);//这句加不加都没关系
                }
            }
            return String.Empty;
        }