Qt TCP/IP网络通信

TCP服务器部分：

创建TCP服务器：
#include    
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socket

    connect(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    
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);
}