用qt写一段代理层的代码实现两个上位机通过代理连接两个下位机，两个下位机收到命令后会发送的数据，发送的数据会在两台上位机上同时显示出来

好的，我可以给你提供一个简单的代理层的代码示例，用于连接两个上位机和两个下位机。这个示例使用Qt的网络模块实现网络通信。以下是示例代码：

#include <QTcpServer>
#include <QTcpSocket>

class Proxy : public QObject {
    Q_OBJECT
public:
    Proxy(quint16 up1_port, quint16 up2_port, quint16 down1_port, quint16 down2_port, QObject* parent = nullptr)
        : QObject(parent)
        , m_up1_port(up1_port)
        , m_up2_port(up2_port)
        , m_down1_port(down1_port)
        , m_down2_port(down2_port)
    {
        m_up1_server = new QTcpServer(this);
        connect(m_up1_server, &QTcpServer::newConnection, this, &Proxy::onUp1Connection);
        m_up1_server->listen(QHostAddress::Any, m_up1_port);

        m_up2_server = new QTcpServer(this);
        connect(m_up2_server, &QTcpServer::newConnection, this, &Proxy::onUp2Connection);
        m_up2_server->listen(QHostAddress::Any, m_up2_port);

        m_down1_socket = new QTcpSocket(this);
        connect(m_down1_socket, &QTcpSocket::readyRead, this, &Proxy::onDown1ReadyRead);
        m_down1_socket->connectToHost(QHostAddress::LocalHost, m_down1_port);

        m_down2_socket = new QTcpSocket(this);
        connect(m_down2_socket, &QTcpSocket::readyRead, this, &Proxy::onDown2ReadyRead);
        m_down2_socket->connectToHost(QHostAddress::LocalHost, m_down2_port);
    }

private slots:
    void onUp1Connection() {
        QTcpSocket* up1_socket = m_up1_server->nextPendingConnection();
        connect(up1_socket, &QTcpSocket::readyRead, this, [this, up1_socket]() {
            QByteArray data = up1_socket->readAll();
            m_down1_socket->write(data);
            m_down2_socket->write(data);
        });
    }

    void onUp2Connection() {
        QTcpSocket* up2_socket = m_up2_server->nextPendingConnection();
        connect(up2_socket, &QTcpSocket::readyRead, this, [this, up2_socket]() {
            QByteArray data = up2_socket->readAll();
            m_down1_socket->write(data);
            m_down2_socket->write(data);
        });
    }

    void onDown1ReadyRead() {
        QByteArray data = m_down1_socket->readAll();
        emit dataReceived(data);
    }

    void onDown2ReadyRead() {
        QByteArray data = m_down2_socket->readAll();
        emit dataReceived(data);
    }

signals:
    void dataReceived(const QByteArray& data);

private:
    QTcpServer* m_up1_server;
    QTcpServer* m_up2_server;
    QTcpSocket* m_down1_socket;
    QTcpSocket* m_down2_socket;
    quint16 m_up1_port;
    quint16 m_up2_port;
    quint16 m_down1_port;
    quint16 m_down2_port;
};

这个代理类有四个端口参数：`up1_port`和`up2_port`是两个上位机的监听端口，`down1_port`和`down2_port`是两个下位机的端口。当上位机连接到代理的监听端口时，代理会将上位机发送的数据转发到两个下位机。当两个下位机有数据发送时，代理会发出`dataReceived`信号，上位机可以监听这个信号并显示接收到的数据。

你需要在两个上位机程序中创建两个`QTcpSocket`对象，并分别连接到代理的`up1_port`和`up2_port`端口。当你想要向下位机发送数据时，你可以使用`QTcpSocket::write`函数将数据发送到代理的相应端口。当代理接收到下位机的数据时，它会发出`dataReceived`信号，你需要连接到这个信号并读取接收到的数据。

注意：这个示例代码可能不是完整的、可编译的程序，它只是提供了一个简单的代理层的实现思路。你需要根据自己的实际需求进行修改和完善。