用qt写一段socket代理的代码实现两个上位机同时连接两个下位机，并通过上位机下发命令

好的，我可以为您提供一个基本的socket代理代码，您可以在此基础上根据您的具体需求进行修改：

#include <QtNetwork>

// 代理类
class SocketProxy : public QObject
{
    Q_OBJECT
public:
    SocketProxy(QObject *parent = nullptr) : QObject(parent)
    {
        // 初始化上位机到下位机的socket
        m_clientSocket1 = new QTcpSocket(this);
        m_clientSocket2 = new QTcpSocket(this);

        // 连接到下位机
        m_clientSocket1->connectToHost("下位机1IP", "下位机1端口");
        m_clientSocket2->connectToHost("下位机2IP", "下位机2端口");

        // 监听上位机连接
        m_server = new QTcpServer(this);
        connect(m_server, &QTcpServer::newConnection, this, &SocketProxy::onNewConnection);
        m_server->listen(QHostAddress::Any, "代理端口");
    }

private slots:
    // 处理新的连接
    void onNewConnection()
    {
        QTcpSocket *clientSocket = m_server->nextPendingConnection();
        if (m_clientSocket1->state() == QAbstractSocket::ConnectedState && m_clientSocket2->state() == QAbstractSocket::ConnectedState)
        {
            // 如果两个下位机都已连接，则转发数据
            connect(clientSocket, &QTcpSocket::readyRead, this, &SocketProxy::onReadyRead);
            connect(clientSocket, &QTcpSocket::disconnected, clientSocket, &QTcpSocket::deleteLater);
        }
        else
        {
            // 如果有下位机未连接，则关闭该连接
            clientSocket->close();
            clientSocket->deleteLater();
        }
    }

    // 转发数据
    void onReadyRead()
    {
        QTcpSocket *clientSocket = qobject_cast<QTcpSocket *>(sender());
        QByteArray data = clientSocket->readAll();
        if (clientSocket == m_clientSocket1)
        {
            m_clientSocket2->write(data);
        }
        else if (clientSocket == m_clientSocket2)
        {
            m_clientSocket1->write(data);
        }
    }

private:
    QTcpServer *m_server;
    QTcpSocket *m_clientSocket1;
    QTcpSocket *m_clientSocket2;
};

// 上位机发送命令的示例代码
void sendCommand()
{
    QTcpSocket socket;
    socket.connectToHost("代理IP", "代理端口");
    if (socket.waitForConnected())
    {
        // 发送命令
        socket.write("command");
        socket.flush();
        socket.waitForBytesWritten();
        socket.disconnectFromHost();
    }
}

使用方法：

1. 将上述代码放入Qt项目中，并且在主函数中创建一个`SocketProxy`对象。

#include "SocketProxy.h"

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

    SocketProxy proxy;

    return a.exec();
}

2. 在需要发送命令的地方调用`sendCommand()`函数即可。

需要注意的是，该代码只是一个简单的示例，您需要根据您的具体需求进行修改，例如添加错误处理、添加多个下位机等。