class Device: public QObject

{

    Q_OBJECT

    Q_PROPERTY(QString update READ getUpdate WRITE setUpdate NOTIFY updateChanged)

public:

    Device();

    ~Device();   

    QString getUpdate();

Q_SIGNALS:

    void updateChanged();

private:

    void setUpdate(const QString &message);

     QString m_message;

实现部分：

QString Device::getUpdate()

{

    return m_message;

}

void Device::setUpdate(const QString &message)

{

    m_message = message;

    emit updateChanged();

}