qt 获取窗口句柄

HWND appwnd;
appwnd = (HWND)w.winId();
QString ClassName("Qt5QWindowIcon");
QString AppName = QStringLiteral("GG");

LPCWSTR app = reinterpret_cast<LPCWSTR>(ClassName.data());
LPCWSTR appCaption = reinterpret_cast<LPCWSTR>(AppName.data());

appwnd = ::FindWindow(app, appCaption);
appwnd = ::FindWindow(app, appCaption);