调出键盘：

  void callKeyboard() {SystemChannels.textInput.invokeMethod<void>('TextInput.show');}

监听按键：

RawKeyboardListener(autofocus: true,onKey: (event) {if (event.runtimeType == RawKeyDownEvent) {if(event.data is RawKeyEventDataAndroid){RawKeyEventDataAndroid datga = event.data as RawKeyEventDataAndroid;///获取按键键值 keycode// _value = datga.keyCode.toString();print('flutter down: '+datga.keyCode.toString());}}