简单的Qml程序，怎么跑不起来？

[xqhrs232]

   QCoreApplication  app(argc, argv);
    QQmlEngine engine;
    MessageBoard  msgBoard;

    engine.rootContext()->setContextProperty("msgBoard",&msgBoard);

   // QQmlComponent component (&engine,QUrl::fromLocalFile("Item.qml"));

     const QUrl url(QStringLiteral("qrc:/item.qml"));
     QQmlComponent component (&engine,url);
     component.create();

    return app.exec();

[xqhrs232]

原来是因为item.qml是个无界面的qml，程序跑起来了，好像没显示