Qt判断网络连接

1. 判断网络连接，但不一定能上网

QNetworkConfigurationManager

bool NetCheck::checkNetworkConnect()
{
    QNetworkConfigurationManager netMgr;
    if (netMgr.isOnline())
    {
        qDebug() << "Connected!" << endl;
        return true;
    }
    else
    {
        qDebug() << "Not Connected!" << endl;
        return false;
    }
}

2. 判断能否上网

QHostInfo

void NetCheck::checkNetworkOnline()
{
    QHostInfo::lookupHost("www.baidu.com", this, SLOT(lookupHostSlot(QHostInfo)));
}
void NetCheck::lookupHostSlot(QHostInfo host)
{
    if (host.error() != QHostInfo::NoError)
    {
        qDebug() << "Not Online!  " + host.errorString() << endl;
    }
    else
    {
        qDebug() << "Online!" << endl;
    }
}

有网络连接但不能上网时，会等待几秒出结果

3. 网络状态变化

QNetworkConfigurationManager

QNetworkConfigurationManager mgr;
connect(&mgr, SIGNAL(onlineStateChanged(bool)), this, SLOT(onlineStateChangedSlot(bool)));
void NetCheck::onlineStateChangedSlot(bool state)
{
    if (state)
        qDebug() << "Changed to Online!" << endl;
    else
        qDebug() << "Changed to Offline!" << endl;
}