QT实现一个局域网聊天功能客户端和服务端代码

以下是一个基于QT的简单局域网聊天程序的客户端和服务端代码：

服务端代码：

#include <QTcpSocket>
#include <QTcpServer>
#include <QNetworkInterface>
#include <QHostAddress>

QTcpServer *server;
QTcpSocket *socket;

void sendMessage(QString message)
{
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);
    out << message.size();
    out << message;
    socket->write(block);
}

void newConnection()
{
    socket = server->nextPendingConnection();
    QObject::connect(socket, &QTcpSocket::readyRead, []() {
        QDataStream in(socket);
        if (socket->bytesAvailable() < (int)sizeof(quint16))
            return;
        quint16 blockSize;
        in >> blockSize;

        if (socket->bytesAvailable() < blockSize)
            return;

        QString message;
        in >> message;
        // handle message

    });
}

void startServer()
{
    server = new QTcpServer();
    QObject::connect(server, &QTcpServer::newConnection, newConnection);
    if (!server->listen(QHostAddress::Any, 12345)) {
        qDebug() << "failed to start server";
        return;
    }
    qDebug() << "server started";
}

void sendMessageToAll(QString message)
{
    for (auto socket : server->children()) {
        if (QTcpSocket *client = qobject_cast<QTcpSocket *>(socket)) {
            sendMessage(message);
        }
    }
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    startServer();

    return a.exec();
}

客户端代码：

#include <QTcpSocket>
#include <QDataStream>

QTcpSocket *socket;

void connectToServer()
{
    socket = new QTcpSocket();
    socket->connectToHost(QHostAddress("127.0.0.1"), 12345);
    QObject::connect(socket, &QTcpSocket::connected, []() {
        qDebug() << "connected to server";
    });
    QObject::connect(socket, &QTcpSocket::readyRead, []() {
        QDataStream in(socket);
        if (socket->bytesAvailable() < (int)sizeof(quint16))
            return;
        quint16 blockSize;
        in >> blockSize;

        if (socket->bytesAvailable() < blockSize)
            return;

        QString message;
        in >> message;
        // handle message

    });
}

void sendMessage(QString message)
{
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);
    out << message.size();
    out << message;
    socket->write(block);
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    connectToServer();

    sendMessage("hello world");

    return a.exec();
}

以上代码实现了一个简单的局域网聊天程序，服务端监听端口等待连接，客户端连接到服务端并发送消息，服务端接收消息并处理。客户端和服务端代码中都实现了发送消息的函数 `sendMessage`，使用 `QDataStream` 对消息进行序列化，并使用 `QTcpSocket` 发送和接收数据。