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Qt UDP 通信的详细实现步骤和示例代码

news 来源：原创 2025/4/20 5:58:36

在 Qt 中实现 UDP 通信主要使用 QUdpSocket 类。以下是 UDP 通信的详细实现步骤和示例代码：

一、UDP 通信基础

无连接协议：不需要建立持久连接
数据报模式：以独立数据包（datagram）形式发送
适用场景：实时性要求高、允许少量丢包（如视频流、游戏、传感器数据）

二、核心类 `QUdpSocket`

1. 发送数据流程

// 创建 socket 对象
QUdpSocket *udpSocket = new QUdpSocket(this);// 准备数据
QByteArray datagram = "Hello UDP!";
QHostAddress targetAddress = QHostAddress("192.168.1.100");
quint16 targetPort = 1234;// 发送数据报（单播）
qint64 bytesSent = udpSocket->writeDatagram(datagram, targetAddress, targetPort);// 广播示例（发送到所有子网设备）
// udpSocket->writeDatagram(datagram, QHostAddress::Broadcast, 1234);

2. 接收数据流程

// 创建 socket 并绑定端口
QUdpSocket *udpSocket = new QUdpSocket(this);
bool bindResult = udpSocket->bind(1234);  // 绑定接收端口// 连接信号槽
connect(udpSocket, &QUdpSocket::readyRead, [=]() {while (udpSocket->hasPendingDatagrams()) {QByteArray datagram;datagram.resize(udpSocket->pendingDatagramSize());QHostAddress senderAddress;quint16 senderPort;udpSocket->readDatagram(datagram.data(), datagram.size(),&senderAddress, &senderPort);qDebug() << "Received from" << senderAddress.toString() << ":" << senderPort<< "Data:" << datagram;}
});// 错误处理
connect(udpSocket, &QUdpSocket::errorOccurred, [=](QAbstractSocket::SocketError error){qDebug() << "UDP Error:" << udpSocket->errorString();
});

三、多播（组播）实现

// 加入多播组
QHostAddress multicastGroup("239.255.43.21");
udpSocket->joinMulticastGroup(multicastGroup);// 设置TTL（生存时间）
udpSocket->setSocketOption(QAbstractSocket::MulticastTtlOption, 1);// 发送多播数据
udpSocket->writeDatagram(datagram, multicastGroup, 1234);// 离开多播组
udpSocket->leaveMulticastGroup(multicastGroup);

四、完整示例

发送端类

class UdpSender : public QObject {
public:UdpSender(QObject *parent = nullptr) : QObject(parent) {socket = new QUdpSocket(this);}void sendMessage(const QString &message, const QHostAddress &target, quint16 port) {QByteArray data = message.toUtf8();socket->writeDatagram(data, target, port);}private:QUdpSocket *socket;
};

接收端类

class UdpReceiver : public QObject {Q_OBJECT
public:UdpReceiver(quint16 port, QObject *parent = nullptr) : QObject(parent) {socket = new QUdpSocket(this);connect(socket, &QUdpSocket::readyRead, this, &UdpReceiver::processPendingDatagrams);socket->bind(port);}private slots:void processPendingDatagrams() {while (socket->hasPendingDatagrams()) {QByteArray datagram;datagram.resize(socket->pendingDatagramSize());QHostAddress sender;quint16 senderPort;socket->readDatagram(datagram.data(), datagram.size(), &sender, &senderPort);emit messageReceived(QString::fromUtf8(datagram), sender.toString(), senderPort);}}signals:void messageReceived(const QString &message, const QString &senderIp, quint16 senderPort);private:QUdpSocket *socket;
};