private void FrmMain_KeyDown(object sender, KeyEventArgs e) {     if (e.Alt && e.Shift && e.Control && e.KeyCode == Keys.S)     {  MessageBox.Show("我按了Control +Shift +Alt +S");     } }

public class AppHotKey {         [DllImport("kernel32.dll")]         public static extern uint GetLastError();         //如果函数执行成功，返回值不为0。         //如果函数执行失败，返回值为0。要得到扩展错误信息，调用GetLastError。         [DllImport("user32.dll", SetLastError = true)]         public static extern bool RegisterHotKey(             IntPtr hWnd,                //要定义热键的窗口的句柄             int id,                     //定义热键ID（不能与其它ID重复）                       KeyModifiers fsModifiers,   //标识热键是否在按Alt、Ctrl、Shift、Windows等键时才会生效             Keys vk                     //定义热键的内容             );         [DllImport("user32.dll", SetLastError = true)]         public static extern bool UnregisterHotKey(             IntPtr hWnd,                //要取消热键的窗口的句柄             int id                      //要取消热键的ID             );         //定义了辅助键的名称（将数字转变为字符以便于记忆，也可去除此枚举而直接使用数值）         [Flags()]         public enum KeyModifiers         {             None = 0,             Alt = 1,             Ctrl = 2,             Shift = 4,             WindowsKey = 8         }         /// <summary>         /// 注册热键         /// </summary>         /// <param name="hwnd">窗口句柄</param>         /// <param name="hotKey_id">热键ID</param>         /// <param name="keyModifiers">组合键</param>         /// <param name="key">热键</param>         public static void RegKey(IntPtr hwnd, int hotKey_id, KeyModifiers keyModifiers, Keys key)         {             try             {                 if (!RegisterHotKey(hwnd, hotKey_id, keyModifiers, key))                 {                     if (Marshal.GetLastWin32Error() == 1409) { MessageBox.Show("热键被占用 ！"); }                     else                     {                         MessageBox.Show("注册热键失败！");                     }                 }             }             catch (Exception) { }         }         /// <summary>         /// 注销热键         /// </summary>         /// <param name="hwnd">窗口句柄</param>         /// <param name="hotKey_id">热键ID</param>         public static void UnRegKey(IntPtr hwnd, int hotKey_id)         {             //注销Id号为hotKey_id的热键设定             UnregisterHotKey(hwnd, hotKey_id);         } }

private const int WM_HOTKEY = 0x312; //窗口消息-热键 private const int WM_CREATE = 0x1; //窗口消息-创建 private const int WM_DESTROY = 0x2; //窗口消息-销毁 private const int Space = 0x3572; //热键ID protected override void WndProc(ref Message m) {     base.WndProc(ref m);     switch (m.Msg)     {  case WM_HOTKEY: //窗口消息-热键ID      switch (m.WParam.ToInt32())      {   case Space: //热键ID       MessageBox.Show("我按了Control +Shift +Alt +S");       break;   default:       break;      }      break;  case WM_CREATE: //窗口消息-创建      AppHotKey.RegKey(Handle, Space, AppHotKey.KeyModifiers.Ctrl | AppHotKey.KeyModifiers.Shift | AppHotKey.KeyModifiers.Alt, Keys.S);      break;  case WM_DESTROY: //窗口消息-销毁      AppHotKey.UnRegKey(Handle, Space); //销毁热键      break;  default:      break;     } }