TCP服务器部分：

创建TCP服务器：
#include    <QTcpServer>
QTcpServer *tcpServer; //TCP服务器
tcpServer=new QTcpServer(this);TCP服务器来连接的信号与槽：
connect(tcpServer,SIGNAL(newConnection()),this,SLOT(onNewConnection()));创建TCP套接字：
QTcpSocket *tcpSocket;//TCP通讯的Socket
在槽函数中：
void MainWindow::onNewConnection()
{
//    ui->plainTextEdit->appendPlainText("有新连接");tcpSocket = tcpServer->nextPendingConnection(); //创建socketconnect(tcpSocket, SIGNAL(connected()),this, SLOT(onClientConnected()));onClientConnected();//connect(tcpSocket, SIGNAL(disconnected()),this, SLOT(onClientDisconnected()));connect(tcpSocket,SIGNAL(stateChanged(QAbstractSocket::SocketState)),this,SLOT(onSocketStateChange(QAbstractSocket::SocketState)));onSocketStateChange(tcpSocket->state());connect(tcpSocket,SIGNAL(readyRead()),this,SLOT(onSocketReadyRead()));
}相关槽函数：
void MainWindow::onClientConnected()
{//客户端接入时ui->plainTextEdit->appendPlainText("**client socket connected");ui->plainTextEdit->appendPlainText("**peer address:"+tcpSocket->peerAddress().toString());ui->plainTextEdit->appendPlainText("**peer port:"+QString::number(tcpSocket->peerPort()));
}void MainWindow::onClientDisconnected()
{//客户端断开连接时ui->plainTextEdit->appendPlainText("**client socket disconnected");tcpSocket->deleteLater();//    deleteLater();//QObject::deleteLater();
}void MainWindow::onSocketStateChange(QAbstractSocket::SocketState socketState)
{//socket状态变化时switch(socketState){case QAbstractSocket::UnconnectedState:LabSocketState->setText("scoket状态：UnconnectedState");break;case QAbstractSocket::HostLookupState:LabSocketState->setText("scoket状态：HostLookupState");break;case QAbstractSocket::ConnectingState:LabSocketState->setText("scoket状态：ConnectingState");break;case QAbstractSocket::ConnectedState:LabSocketState->setText("scoket状态：ConnectedState");break;case QAbstractSocket::BoundState:LabSocketState->setText("scoket状态：BoundState");break;case QAbstractSocket::ClosingState:LabSocketState->setText("scoket状态：ClosingState");break;case QAbstractSocket::ListeningState:LabSocketState->setText("scoket状态：ListeningState");}
}void MainWindow::onSocketReadyRead()
{//读取缓冲区行文本
//    QStringList   lines;while(tcpSocket->canReadLine())ui->plainTextEdit->appendPlainText("[in] "+tcpSocket->readLine());
//        lines.append(clientConnection->readLine());
}服务器开始监听：
tcpServer->listen(addr,port);//
停止监听：
if (tcpServer->isListening()) //tcpServer正在监听{tcpServer->close();//停止监听
}发送数据：
void MainWindow::on_btnSend_clicked()
{//发送一行字符串，以换行符结束QString  msg=ui->editMsg->text();ui->plainTextEdit->appendPlainText("[out] "+msg);ui->editMsg->clear();ui->editMsg->setFocus();QByteArray  str=msg.toUtf8();str.append('\n');//添加一个换行符tcpSocket->write(str);
}

TCP客户端部分：

#include    <QTcpSocket>
创建TCP套接字：
QTcpSocket  *tcpClient;  
tcpClient=new QTcpSocket(this); //创建socket变量
连接相关信号与槽：
connect(tcpClient,SIGNAL(connected()),this,SLOT(onConnected()));connect(tcpClient,SIGNAL(disconnected()),this,SLOT(onDisconnected()));connect(tcpClient,SIGNAL(stateChanged(QAbstractSocket::SocketState)),this,SLOT(onSocketStateChange(QAbstractSocket::SocketState)));connect(tcpClient,SIGNAL(readyRead()),this,SLOT(onSocketReadyRead()));void MainWindow::onSocketReadyRead()
{//readyRead()信号槽函数while(tcpClient->canReadLine())ui->plainTextEdit->appendPlainText("[in] "+tcpClient->readLine());
}
连接到服务器：
tcpClient->connectToHost(addr,port);
断开连接：
if (tcpClient->state()==QAbstractSocket::ConnectedState)tcpClient->disconnectFromHost();
发送数据：
void MainWindow::on_btnSend_clicked()
{//发送数据QString  msg=ui->editMsg->text();ui->plainTextEdit->appendPlainText("[out] "+msg);ui->editMsg->clear();ui->editMsg->setFocus();QByteArray  str=msg.toUtf8();str.append('\n');tcpClient->write(str);
}