使用QDBusInterface，调用DBus接口

// 创建QDBusInterface
        QDBusInterface iface("org.onboard.Onboard",
                             "/org/onboard/Onboard/Keyboard",
                             "org.onboard.Onboard.Keyboard");
        if (!iface.isValid()) {
            qInfo() << qPrintable(QDBusConnection::sessionBus().lastError().message());
        }
        QDBusReply<void> reply = iface.call("Show");
        if (reply.isValid()) {
            qInfo() << "call org.onboard.Onboard.Keyboard success";
            return;
        }
        qInfo() << "call corg.onboard.Onboard.Keyboard failed" << reply.error();
    });