QUdpSocket 简单用法

UDP是无连接的不可靠的传输协议，可以用在可靠传输不是很重要的情况下使用。 QUdpSocket是QAbstractSocket 的子类，它们都继承了QIODevice。所以可以用QUdpSocket进行发送接收数据。它和QTcpSocket最大的区别也就是，发送数据之前不需要建立连接。以下简单例子，演示了用QUdpSocket如何实现客户端和服务端的通信。

服务端代码：

class UDPServer:public QObject
{
Q_OBJECT
public:
UDPServer(QObject *parent = NULL);
~UDPServer();
private slots:
void readPendingDatagrams();
private:
QUdpSocket           *udpSocket;

};

UDPServer::UDPServer(QObject *parent /* = NULL */):QObject(parent)
{
udpSocket = new QUdpSocket(this);
udpSocket->bind(QHostAddress::LocalHost, 7755);
cout<<"Server is Running......"<<endl;
connect(udpSocket, SIGNAL(readyRead()),this, SLOT(readPendingDatagrams()));
}

UDPServer::~UDPServer()
{

}

void UDPServer::readPendingDatagrams()
{
QHostAddress sender;
quint16 senderPort;
while (udpSocket->hasPendingDatagrams())
{
QByteArray datagram;
datagram.resize(udpSocket->pendingDatagramSize());
udpSocket->readDatagram(datagram.data(), datagram.size(),&sender, &senderPort);
string strMes(datagram);
std::cout<<strMes<<endl;
}
QString text = "hello ...";
QByteArray datagram = text.toLocal8Bit();
udpSocket->writeDatagram(datagram.data(),datagram.size(),sender, senderPort);
}

说明：

我都是在自己的机器上测试，所以服务器地址都是localHost。即

udpSocket->bind(QHostAddress::LocalHost, 7755);

给客户端回发信息

udpSocket->writeDatagram(datagram.data(),datagram.size(),sender, senderPort);

客户端代码：

class UdpClient : public QWidget
{
Q_OBJECT

public:
UdpClient(QWidget *parent = 0, Qt::WFlags flags = 0);
~UdpClient();

private slots:
void sendMessageSlot();
void readPendingDatagrams();
private:
QUdpSocket     *udpSocket;
QLineEdit      *m_pLEdit;
QPushButton    *m_pSendMesBtn;
QLabel         *m_pMessage;
//Ui::UdpClientClass ui;
};

UdpClient::UdpClient(QWidget *parent, Qt::WFlags flags)
: QWidget(parent, flags)
{
m_pLEdit = new QLineEdit(this);
m_pSendMesBtn = new QPushButton(tr("Sending"),this);
udpSocket = new QUdpSocket(this);
m_pMessage = new QLabel(this);
QHostAddress sender = udpSocket->localAddress();
quint16 senderPort = udpSocket->localPort();
udpSocket->bind(sender,senderPort);
m_pLEdit->setGeometry(5,5,100,20);
m_pSendMesBtn->setGeometry(110,5,50,20);
m_pMessage->setGeometry(5,30,150,20);
m_pLEdit->setStyleSheet("QLineEdit{color:red}");
connect(m_pSendMesBtn, SIGNAL(clicked()),this, SLOT(sendMessageSlot()));
connect(udpSocket, SIGNAL(readyRead()),this, SLOT(readPendingDatagrams()));

//ui.setupUi(this);

}

UdpClient::~UdpClient()
{

}

void UdpClient::sendMessageSlot()
{
QString text = m_pLEdit->text();
QByteArray datagram = text.toLocal8Bit();
udpSocket->writeDatagram(datagram.data(),datagram.size(),QHostAddress::LocalHost, 7755);
}

void UdpClient::readPendingDatagrams()
{
while (udpSocket->hasPendingDatagrams())
{
QByteArray datagram;
datagram.resize(udpSocket->pendingDatagramSize());
QHostAddress sender;
quint16 senderPort;
udpSocket->readDatagram(datagram.data(), datagram.size(),&sender, &senderPort);
QString text = QString(datagram);
m_pMessage->setText(text);
}
}

说明：

绑定本地地址和端口，以接收客户端发过来的信息

QHostAddress sender = udpSocket->localAddress();
quint16 senderPort = udpSocket->localPort();
udpSocket->bind(sender,senderPort);

演示结果图：