qt代理实现一台下位机分别连接两个上位机‘’

我们可以通过Qt提供的`QTcpSocket`和`QTcpServer`类实现代理的功能，在下位机上运行一个代理程序，将来自两个上位机的请求分别转发到另一个上位机。下面是一个简单的示例代码：

#include <QtNetwork/QTcpServer>
#include <QtNetwork/QTcpSocket>
#include <QtCore/QDebug>

int main(int argc, char *argv[])
{
    int port1 = 1234;   // 上位机1的端口号
    int port2 = 5678;   // 上位机2的端口号
    QString host1 = "192.168.1.100";   // 上位机1的IP地址
    QString host2 = "192.168.1.101";   // 上位机2的IP地址

    QTcpServer server;
    if (!server.listen(QHostAddress::Any, 8888)) {   // 监听代理端口号8888
        qDebug() << "Unable to start the server";
        return 1;
    }
    qDebug() << "Server started, listening on port " << server.serverPort();

    while(true) {
        if(!server.waitForNewConnection(1000)) {
            qDebug() << "Timeout waiting for client connection";
            continue;
        }

        QTcpSocket *client = server.nextPendingConnection();

        qDebug() << "New client connected from " << client->peerAddress().toString() << ":" << client->peerPort();

        // 根据连接的端口号和IP地址判断是哪个上位机连接过来的
        if (client->peerAddress().toString() == host1 && client->peerPort() == port1) {
            // 连接上位机1
            QTcpSocket *socket1 = new QTcpSocket;
            socket1->connectToHost(host2, port2);
            QObject::connect(socket1, &QTcpSocket::readyRead, [=]() {
                // 上位机1有数据发送过来，转发到上位机2
                client->write(socket1->readAll());
            });
            QObject::connect(client, &QTcpSocket::readyRead, [=]() {
                // 上位机2有数据发送过来，转发到上位机1
                socket1->write(client->readAll());
            });
            QObject::connect(client, &QTcpSocket::disconnected, [=]() {
                // 上位机1断开连接，断开与上位机2的连接
                socket1->close();
                socket1->deleteLater();
            });
        } else if (client->peerAddress().toString() == host2 && client->peerPort() == port2) {
            // 连接上位机2
            QTcpSocket *socket2 = new QTcpSocket;
            socket2->connectToHost(host1, port1);
            QObject::connect(socket2, &QTcpSocket::readyRead, [=]() {
                // 上位机2有数据发送过来，转发到上位机1
                client->write(socket2->readAll());
            });
            QObject::connect(client, &QTcpSocket::readyRead, [=]() {
                // 上位机1有数据发送过来，转发到上位机2
                socket2->write(client->readAll());
            });
            QObject::connect(client, &QTcpSocket::disconnected, [=]() {
                // 上位机2断开连接，断开与上位机1的连接
                socket2->close();
                socket2->deleteLater();
            });
        }

    }

    return 0;
}

以上代码中，我们通过`QTcpServer`监听代理端口号8888，当有新的连接请求时，我们根据连接的IP地址和端口号判断是哪个上位机连接过来的，并分别创建一个`QTcpSocket`对象连接到另一个上位机。当有数据发送过来时，我们通过`write()`函数将数据转发到另一个上位机。当有一方断开连接时，我们关闭与另一个上位机的连接并释放`QTcpSocket`对象。