UDP发广播给所有网卡（包含虚拟网卡）

//给所有网卡发广播

QList<QNetworkInterface> networkinterfaces = QNetworkInterface::allInterfaces();

foreach (QNetworkInterface interface, networkinterfaces)

{

    foreach (QNetworkAddressEntry entry, interface.addressEntries())

    {

        QHostAddress broadcastAddress = entry.broadcast();

        if (broadcastAddress != QHostAddress::Null

              && entry.ip() != QHostAddress::LocalHost

              && entry.ip().protocol() == QAbstractSocket::IPv4Protocol

            )

        {

            udpSocketServer.writeDatagram(datagram, broadcastAddress, 13999);  // UDP 发送数据

         }

     }

}

UDP简单的使用：http://blog.csdn.net/u014597198/article/details/53509011

可以把其中的onServerSendBroadcast（）函数用以下函数替换一下，就可以给机器内所有网卡发广播了

void UDPServerAndClient::onServerSendBroadcast()
{
    QByteArray datagram;
    QDataStream out(&datagram, QIODevice::WriteOnly);
    out.setVersion(QDataStream::Qt_5_6);
    out << QDateTime::currentDateTime() << QHostInfo::fromName(QHostInfo::localHostName()).addresses().last().toString();

  //给所有网卡发广播

    QList networkinterfaces = QNetworkInterface::allInterfaces();
    foreach (QNetworkInterface interface, networkinterfaces)
    {
    	foreach (QNetworkAddressEntry entry, interface.addressEntries())
    	{
        	QHostAddress broadcastAddress = entry.broadcast();
        	if (broadcastAddress != QHostAddress::Null
              	&& entry.ip() != QHostAddress::LocalHost
              	&& entry.ip().protocol() == QAbstractSocket::IPv4Protocol
            	)
        	{
            		udpSocketServer.writeDatagram(datagram, broadcastAddress, 13999);  // UDP 发送数据
         	}
     	}
     }

}