Question

我正在尝试从连接LAN的红外摄像机获取数据。我不知道如何处理来自外部网络的数据包。这是我的代码。

以下代码在Qt 5.9.7（msvc2017_64）上运行。我已从Qt UDP示例更改了代码。（https://www.bogotobogo.com/Qt/Qt5_QUdpSocket.php）

#include "myudp.h"
MyUDP::MyUDP(QObject *parent) :
QObject(parent)
{
// create a QUDP socket
socket = new QUdpSocket(this);
socket_cam = new QUdpSocket(this);
// The most common way to use QUdpSocket class is
// to bind to an address and port using bind()
// bool QAbstractSocket::bind(const QHostAddress & address,
//     quint16 port = 0, BindMode mode = DefaultForPlatform)
socket->bind(QHostAddress::LocalHost, 1234);

connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
}

void MyUDP::HelloUDP()
{
QByteArray Data;

QHostAddress camera_loc = QHostAddress("192.168.10.197");
quint16 cameraPort = 32197;

qint64 deg_num = socket->readDatagram(Data.data() ,964, &camera_loc, 
&cameraPort);
qDebug() << "Deg_num: " << deg_num; //this returns -1. Therefore, it 
seems it can't read any data from camera_loc.
// Sends the datagram datagram
// to the host address and at port.
// qint64 QUdpSocket::writeDatagram(const QByteArray & datagram,
//                      const QHostAddress & host, quint16 port)
socket->writeDatagram(Data, QHostAddress::LocalHost, 1234);
}

void MyUDP::readyRead()
{
// when data comes in
QByteArray buffer;
buffer.resize(socket->pendingDatagramSize());

QHostAddress sender = QHostAddress("192.168.10.197");
quint16 senderPort = 32197;

// qint64 QUdpSocket::readDatagram(char * data, qint64 maxSize,
//                 QHostAddress * address = 0, quint16 * port = 0)
// Receives a datagram no larger than maxSize bytes and stores it 
// The sender's host address and port is stored in *address and *port
// (unless the pointers are 0).

socket->readDatagram(buffer.data(), buffer.size(),
                     &sender, &senderPort);
qDebug() << "Message from: " << sender.toString();
qDebug() << "Message port: " << senderPort;
qDebug() << "Message: " << buffer;
}

正如我在Wireshark上看到的那样，数据包按预期正确到达。但是，我的代码无法正常工作。（camera_loc上的readDatagram返回（-1））根据其他线程，我们不需要连接它们，因为UDP通信不需要建立连接。我想用这段代码制作如下。

（0。使用readDatagram将来自摄像机（192.168.10.197）的数据保存在变量上）我不确定这是否是真正必要的过程... 1.按照此代码中的说明将数据写入缓冲区（使用writeDatagram函数）。

即使我挣扎，我也找不到解决方案。我以为这很容易，但事实并非如此。任何建议将不胜感激，因为我是qt和UDP网络的新手。

先谢谢了。

尝试使用Qt网络访问通过LAN连接的摄像机

0 个答案: