qt做客户端 linux服务器 利用TCP实现登陆注册

下面是一个简单的示例代码，演示如何利用Qt实现TCP通信，实现客户端登陆注册功能：

客户端代码：

#include <QtNetwork>
#include <QDataStream>
#include <QDebug>

class Client : public QObject
{
    Q_OBJECT

public:
    Client(QObject *parent = nullptr)
        : QObject(parent)
    {
        m_socket = new QTcpSocket(this);

        connect(m_socket, &QTcpSocket::connected, this, &Client::onConnected);
        connect(m_socket, &QTcpSocket::disconnected, this, &Client::onDisconnected);
        connect(m_socket, &QTcpSocket::readyRead, this, &Client::onReadyRead);
        connect(m_socket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error), this, &Client::onError);

        m_socket->connectToHost("127.0.0.1", 1234);
    }

    void login(const QString &username, const QString &password)
    {
        QByteArray data;
        QDataStream stream(&data, QIODevice::WriteOnly);
        stream << qint8(1) << username << password;
        m_socket->write(data);
    }

    void registerUser(const QString &username, const QString &password)
    {
        QByteArray data;
        QDataStream stream(&data, QIODevice::WriteOnly);
        stream << qint8(2) << username << password;
        m_socket->write(data);
    }

private slots:
    void onConnected()
    {
        qDebug() << "Connected to server.";
    }

    void onDisconnected()
    {
        qDebug() << "Disconnected from server.";
    }

    void onReadyRead()
    {
        QDataStream stream(m_socket);
        while (!stream.atEnd()) {
            qint8 cmd;
            stream >> cmd;

            switch (cmd) {
            case 1: { // login response
                bool success;
                stream >> success;
                if (success) {
                    qDebug() << "Login successful.";
                } else {
                    qDebug() << "Login failed.";
                }
                break;
            }
            case 2: { // register response
                bool success;
                stream >> success;
                if (success) {
                    qDebug() << "Registration successful.";
                } else {
                    qDebug() << "Registration failed.";
                }
                break;
            }
            default:
                qDebug() << "Unknown command:" << cmd;
                break;
            }
        }
    }

    void onError(QAbstractSocket::SocketError error)
    {
        qDebug() << "Socket error:" << error << m_socket->errorString();
    }

private:
    QTcpSocket *m_socket;
};

服务器端代码：

#include <QtNetwork>
#include <QDataStream>
#include <QDebug>

class Server : public QObject
{
    Q_OBJECT

public:
    Server(QObject *parent = nullptr)
        : QObject(parent)
    {
        m_server = new QTcpServer(this);

        connect(m_server, &QTcpServer::newConnection, this, &Server::onNewConnection);

        if (!m_server->listen(QHostAddress::Any, 1234)) {
            qDebug() << "Failed to start server:" << m_server->errorString();
            return;
        }

        qDebug() << "Listening on port 1234...";
    }

private slots:
    void onNewConnection()
    {
        QTcpSocket *socket = m_server->nextPendingConnection();
        qDebug() << "New connection from" << socket->peerAddress().toString() << socket->peerPort();

        connect(socket, &QTcpSocket::disconnected, socket, &QTcpSocket::deleteLater);
        connect(socket, &QTcpSocket::readyRead, this, &Server::onReadyRead);
        connect(socket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error), this, &Server::onError);

        m_clients.append(socket);
    }

    void onReadyRead()
    {
        QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
        Q_ASSERT(socket);

        QDataStream stream(socket);
        while (!stream.atEnd()) {
            qint8 cmd;
            stream >> cmd;

            switch (cmd) {
            case 1: { // login request
                QString username, password;
                stream >> username >> password;
                bool success = checkLogin(username, password);
                QByteArray data;
                QDataStream response(&data, QIODevice::WriteOnly);
                response << qint8(1) << success;
                socket->write(data);
                break;
            }
            case 2: { // register request
                QString username, password;
                stream >> username >> password;
                bool success = registerUser(username, password);
                QByteArray data;
                QDataStream response(&data, QIODevice::WriteOnly);
                response << qint8(2) << success;
                socket->write(data);
                break;
            }
            default:
                qDebug() << "Unknown command:" << cmd;
                break;
            }
        }
    }

    void onError(QAbstractSocket::SocketError error)
    {
        QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
        Q_ASSERT(socket);

        qDebug() << "Socket error:" << error << socket->errorString();

        m_clients.removeOne(socket);
        socket->deleteLater();
    }

private:
    bool checkLogin(const QString &username, const QString &password)
    {
        // TODO: check username and password against database
        return true;
    }

    bool registerUser(const QString &username, const QString &password)
    {
        // TODO: add username and password to database
        return true;
    }

    QTcpServer *m_server;
    QList<QTcpSocket *> m_clients;
};

在这个示例中，客户端与服务器端都是单线程的，因此接收到数据时会一直阻塞，直到数据全部接收完成。如果需要支持并发处理，可以将每个连接分配给一个新线程处理。另外，此示例中的用户名和密码是明文传输的，需要添加加密传输的支持来保护用户隐私。