我建了一个Winform程序,现在想在整个屏幕的任意位置按下键盘的的a键,弹出消息框(不只是在这个Form上),可是只能定义Form的KeyPress事件,鼠标出了Form
就没用了...不知道该怎么办,麻烦各位了帮帮忙...

系统钩子

键盘记录器就是这原理，C#应该怎么做还不是很清楚，有待高人解决…

好几个人都说用钩子函数 可惜我还是个新手 还是慢慢来吧!!!

 public Form1()
        {
            InitializeComponent();
            RegisterHotKey(Handle, 100, 2, Keys.Up); // 热键一:Control +光标上箭头
            RegisterHotKey(Handle, 200, 2, Keys.Down); // 热键一:Control +光标下箭头
        }
        [StructLayout(LayoutKind.Sequential)]
        public struct SHFILEINFO
        {
            public IntPtr hIcon;
            public int iIcon;
            public int dwAttributes;
            public string szDisplayName;
            public string szTypeName;
        }
        public enum KeyModifiers
        {
            None = 0,
            Alt = 1,
            Control = 2,
            Shift = 4,
            Windows = 8
        }
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, Keys vk);
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern bool UnregisterHotKey(IntPtr hWnd, int id);
        private void ProcessHotkey(Message m)//触发热键
        {
            try
            {
                IntPtr id = m.WParam;
                string sid = id.ToString();
                switch (sid)
                {
                    case "100":
                        playup();
                        break;
                    case "200":
                        playnext();
                        break;
                }
            }
            catch (Exception W)
            {
                this.label_Error.Text = "错误47:  " + W.Message;
            }
        }
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)//卸载热键
        {
            try
            {
                UnregisterHotKey(Handle, 100); //卸载第1个快捷键
                UnregisterHotKey(Handle, 200); //缷载第2个快捷键
}