QT的Tcp长连接代码

以下是QT的Tcp长连接示例代码：

#include <QTcpSocket>
#include <QTimer>

class TcpClient : public QObject
{
    Q_OBJECT
public:
    explicit TcpClient(QObject *parent = nullptr);

signals:
    void receivedData(const QString &data);

public slots:
    void connectToServer(const QString &host, quint16 port);
    void sendData(const QString &data);
    void disconnectFromServer();

private slots:
    void readData();
    void handleError(QAbstractSocket::SocketError error);
    void reconnect();

private:
    QTcpSocket *m_socket;
    QTimer *m_reconnectTimer;
    QString m_host;
    quint16 m_port;
};

TcpClient::TcpClient(QObject *parent)
    : QObject(parent)
    , m_socket(new QTcpSocket(this))
    , m_reconnectTimer(new QTimer(this))
{
    connect(m_socket, &QTcpSocket::readyRead, this, &TcpClient::readData);
    connect(m_socket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(handleError(QAbstractSocket::SocketError)));
    connect(m_reconnectTimer, &QTimer::timeout, this, &TcpClient::reconnect);
    m_reconnectTimer->setInterval(5000); // 5 seconds
}

void TcpClient::connectToServer(const QString &host, quint16 port)
{
    m_host = host;
    m_port = port;

    m_socket->connectToHost(m_host, m_port);
}

void TcpClient::sendData(const QString &data)
{
    if (m_socket->state() == QTcpSocket::ConnectedState) {
        m_socket->write(data.toUtf8());
    }
}

void TcpClient::disconnectFromServer()
{
    m_socket->disconnectFromHost();
}

void TcpClient::readData()
{
    QString data = QString::fromUtf8(m_socket->readAll());
    emit receivedData(data);
}

void TcpClient::handleError(QAbstractSocket::SocketError error)
{
    switch (error) {
    case QAbstractSocket::RemoteHostClosedError:
        // do nothing
        break;
    case QAbstractSocket::HostNotFoundError:
        qDebug() << "Error: Host not found";
        break;
    case QAbstractSocket::ConnectionRefusedError:
        qDebug() << "Error: Connection refused";
        m_reconnectTimer->start();
        break;
    default:
        qDebug() << "Error:" << m_socket->errorString();
        m_reconnectTimer->start();
        break;
    }
}

void TcpClient::reconnect()
{
    qDebug() << "Trying to reconnect...";
    m_socket->connectToHost(m_host, m_port);
}

这个类实现了一个TCP客户端，它可以连接到一个TCP服务器并发送和接收数据。如果连接中断，它将自动重新连接。要使用它，只需实例化TcpClient，然后连接到它的信号和槽，如下所示：

TcpClient *client = new TcpClient(this);
connect(client, &TcpClient::receivedData, this, &MyClass::handleReceivedData);
client->connectToServer("localhost", 1234);
client->sendData("Hello, server!");
client->disconnectFromServer();