捕获没有焦点的击键

例如，使用winamp（至少在Windows上），您可以在后台使用winamp全屏播放游戏，并使用媒体按钮*来控制声音。 Winamp不需要关注，让游戏继续全屏。

我更喜欢用Java编写这个，但这可能不会起作用（在Java afaik中捕获没有焦点的击键已经很困难了），所以任何C＃解决方案都没问题。

所以基本的问题是：如何在没有焦点的情况下捕获击键？

*）我相信’后退/前进/停止/邮件/搜索/collections夹/网络/主页’按钮被称为媒体按钮，但欢迎更好的名称:)。

Answer 1

低级别的窗户挂钩是一种方法。 这是一篇文章 ，这里有来自MSDN的更多信息。

这是该代码的部分视图：

private IntPtr LowLevelKeyboardHook(int nCode, WindowsMessages wParam, [In] KBDLLHOOKSTRUCT lParam) { bool callNext = true; bool isKeyDown = (wParam == WindowsMessages.KEYDOWN || wParam == WindowsMessages.SYSKEYDOWN); bool isKeyUp = (wParam == WindowsMessages.KEYUP || wParam == WindowsMessages.SYSKEYUP); if ((nCode >= 0) && (isKeyDown || isKeyUp)) { // the virtual key codes and the winforms Keys have the same enumeration // so we can freely cast back and forth between them Keys key = (Keys)lParam.vkCode; // Do your other processing here... } // if any handler returned false, trap the message return (callNext) ? User32.CallNextHookEx(_mainHook, nCode, wParam, lParam) : _nullNext; } /// 
 /// Registers the user's LowLevelKeyboardProc with the system in order to /// intercept any keyboard events before processed in the regular fashion. /// This can be used to log all keyboard events or ignore them. /// 
 /// Callback function to call whenever a keyboard event occurs. /// The IntPtr assigned by the Windows's sytem that defines the callback. private IntPtr RegisterLowLevelHook(LowLevelKeyboardProc hook) { IntPtr handle = IntPtr.Zero; using (Process currentProcess = Process.GetCurrentProcess()) using (ProcessModule currentModule = currentProcess.MainModule) { IntPtr module = Kernel32.GetModuleHandle(currentModule.ModuleName); handle = User32.SetWindowsHookEx(HookType.KEYBOARD_LL, hook, module, 0); } return handle; } /// 
 /// Unregisters a previously registered callback from the low-level chain. /// 
 /// IntPtr previously assigned to the low-level chain. /// Users should have stored the value given by /// , /// and use that value as the parameter into this function. /// True if the hook was removed, false otherwise. private bool UnregisterLowLevelHook(IntPtr hook) { return User32.UnhookWindowsHookEx(hook); } 

只需实现所需的所有P / Invoke声明，它应该可以工作。 我在我的应用程序中使用此方法，它工作正常。

Answer 2

在Java中，有两个库可以执行此操作：

• JIntellitype （Windows）
• JXGrabKey （X11）