Qt的网络编程能力非常强大，它提供了从底层socket API到高层HTTP、FTP等协议处理的完整解决方案。下面将简要介绍Qt中网络编程的核心类及其功能，并给出一些基本的使用示例。

核心网络类：

1. QTcpSocket 和 QTcpServer

   • QTcpSocket 是用于TCP通信的客户端类，可以用来创建TCP连接并发送/接收数据。
     示例：

     // 客户端连接到服务器
     QTcpSocket *client = new QTcpSocket(this);
     client->connectToHost("127.0.0.1", 12345);// 连接成功后发送数据
     if (client->waitForConnected())
     {client->write("Hello Server!");client->disconnectFromHost();
     }// 接收数据
     connect(client, &QTcpSocket::readyRead, [=](){QByteArray data = client->readAll();qDebug() << "Received data:" << data;
     });// 监听错误信号
     connect(client, static_cast<void(QTcpSocket::*)(QAbstractSocket::SocketError)>(&QTcpSocket::error),[](QAbstractSocket::SocketError error){qDebug() << "Error occurred:" << error;});
     

   • QTcpServer 用于监听入站TCP连接请求，并创建新的QTcpSocket实例以处理每个客户端连接。
     示例：

     QTcpServer server;
     if (!server.listen(QHostAddress::Any, 12345))
     {qDebug() << "Unable to start the server: " << server.errorString();return;
     }connect(&server, &QTcpServer::newConnection, [&](QTcpSocket *socket){qDebug() << "New connection accepted from " << socket->peerAddress();// 处理客户端数据connect(socket, &QTcpSocket::readyRead, [=](){QByteArray data = socket->readAll();qDebug() << "Received data from client: " << data;// 回应客户端socket->write("Hello Client!");});// 关闭连接时的处理connect(socket, &QTcpSocket::disconnected, socket, &QTcpSocket::deleteLater);
     });
     

2. QUdpSocket

   • QUdpSocket 类用于无连接的UDP通信，可以发送和接收数据报文。
     发送UDP数据：

     QUdpSocket udpSocket;
     udpSocket.bind(QHostAddress::AnyIPv4, 5555); // 绑定本地端口以便发送数据QByteArray message = "UDP Broadcast";
     udpSocket.writeDatagram(message.data(), message.length(),QHostAddress::Broadcast, 5555);
     

     接收UDP数据：

     QUdpSocket receiver;
     receiver.bind(5555); // 绑定端口接收数据while (true) {QByteArray datagram;QHostAddress sender;quint16 senderPort;if (receiver.hasPendingDatagrams()) {datagram.resize(static_cast<int>(receiver.pendingDatagramSize()));receiver.readDatagram(datagram.data(), datagram.size(), &sender, &senderPort);qDebug() << "Received UDP datagram from" << sender.toString() << ":" << senderPort << ", Data:" << datagram;}
     }
     

3. QNetworkAccessManager

   • QNetworkAccessManager 是用于执行高层网络操作的类，比如HTTP GET/POST请求、FTP上传下载等。
     示例：

     QNetworkAccessManager manager;
     QNetworkRequest request(QUrl("http://example.com/api/data"));// 发送GET请求
     QNetworkReply *reply = manager.get(request);connect(reply, &QNetworkReply::finished, [=](){if (reply->error() == QNetworkReply::NoError) {QByteArray response = reply->readAll();qDebug() << "GET Response: " << response;} else {qDebug() << "Error:" << reply->errorString();}reply->deleteLater();
     });
     

其他辅助类：

• QNetworkInterface 和 QHostInfo 可以用于获取本地主机和远程主机的网络信息，例如IP地址、主机名等。

通过以上核心类，可以构建复杂的网络应用，包括但不限于聊天软件、文件传输系统、Web服务客户端等。