运行截图如下：

cmd远程登录端口号为7

登录后，输入数据，服务器进行回显

Qt服务器：

代码如下：

echoserver.h

#ifndef ECHOSERVER_H
#define ECHOSERVER_H

#include <QObject>
#include <QTcpServer>

class EchoServer : public QTcpServer
{
    Q_OBJECT
public:
    explicit EchoServer(QObject *parent = 0);
    ~EchoServer();

signals:

public slots:

protected slots:
    void onNewConnection();
    void onReadyRead();

private:
    void echo(QTcpSocket *sock);
};

#endif // ECHOSERVER_H

echoserver.cpp

#include "echoserver.h"

#include <QTcpSocket>

EchoServer::EchoServer(QObject *parent) : QTcpServer(parent)
{
    connect(this,SIGNAL(newConnection()),this,SLOT(onNewConnection()));
}

EchoServer::~EchoServer()
{

}

void EchoServer::onNewConnection()
{
    while(hasPendingConnections()){
        QTcpSocket *socket=nextPendingConnection();
        connect(socket,SIGNAL(readyRead()),this,SLOT(onReadyRead()));
        connect(socket,SIGNAL(disconnected()),socket,SLOT(deleteLater()));
        if(socket->bytesAvailable()>0){
            echo(socket);
        }
    }
}

void EchoServer::onReadyRead()
{
    QTcpSocket *sock=qobject_cast<QTcpSocket*>(sender());//取得当前获取数据的socket对象，这个sender就是获取发射信号的对象
    echo(sock);
}

void EchoServer::echo(QTcpSocket *sock)
{
    QByteArray inData=sock->readAll();
    qDebug()<<inData;
    sock->write(inData);
    sock->flush();
}

main.cpp

#include <QApplication>
#include "echoserver.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    EchoServer server;
    server.listen(QHostAddress::Any,7);

    return a.exec();
}