TCP通信（01）

服务器端向客户端发送数据

客户端

#include "tcpclientdialog.h"
#include "ui_tcpclientdialog.h"

TcpClientDialog::TcpClientDialog(QWidget *parent)
    : QDialog(parent)
    , ui(new Ui::TcpClientDialog)
{
    ui->setupUi(this);
    tcpSocket = new QTcpSocket(this);
    connect(tcpSocket, &QTcpSocket::readyRead,
            this, &TcpClientDialog::readMessage);
    connect(tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
            this, SLOT(displayError(QAbstractSocket::SocketError)));
}

TcpClientDialog::~TcpClientDialog()
{
    delete ui;
}

void TcpClientDialog::newConnect()
{
    blockSize = 0;
    tcpSocket->abort();
    tcpSocket->connectToHost(ui->hostLineEdit->text(), 
                             ui->portLineEdit_2->text().toInt());

}

void TcpClientDialog::readMessage()
{
    QDataStream in(tcpSocket);
    in.setVersion(QDataStream::Qt_5_9);
    if(blockSize == 0){
        if(tcpSocket->bytesAvailable() < (int)sizeof(quint16)){
            return;
        }
        in >> blockSize;
    }
    if(tcpSocket->bytesAvailable() < blockSize){
        return;
    }
    in >> message;
    ui->messageLabel->setText(message);

}

void TcpClientDialog::displayError(QAbstractSocket::SocketError)
{
    qDebug() << tcpSocket->errorString();

}


void TcpClientDialog::on_connectButton_clicked()
{
    newConnect();
}

#include "tcpclientdialog.h"
#include "ui_tcpclientdialog.h"

TcpClientDialog::TcpClientDialog(QWidget *parent)
    : QDialog(parent)
    , ui(new Ui::TcpClientDialog)
{
    ui->setupUi(this);
    tcpSocket = new QTcpSocket(this);
    connect(tcpSocket, &QTcpSocket::readyRead,
            this, &TcpClientDialog::readMessage);
    connect(tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
            this, SLOT(displayError(QAbstractSocket::SocketError)));
}

TcpClientDialog::~TcpClientDialog()
{
    delete ui;
}

void TcpClientDialog::newConnect()
{
    blockSize = 0;
    tcpSocket->abort();
    tcpSocket->connectToHost(ui->hostLineEdit->text(), 
                             ui->portLineEdit_2->text().toInt());

}

void TcpClientDialog::readMessage()
{
    QDataStream in(tcpSocket);
    in.setVersion(QDataStream::Qt_5_9);
    if(blockSize == 0){
        if(tcpSocket->bytesAvailable() < (int)sizeof(quint16)){
            return;
        }
        in >> blockSize;
    }
    if(tcpSocket->bytesAvailable() < blockSize){
        return;
    }
    in >> message;
    ui->messageLabel->setText(message);

}

void TcpClientDialog::displayError(QAbstractSocket::SocketError)
{
    qDebug() << tcpSocket->errorString();

}


void TcpClientDialog::on_connectButton_clicked()
{
    newConnect();
}

服务器端

#ifndef TCPSERVERDIALOG_H
#define TCPSERVERDIALOG_H

#include <QDialog>
#include <QtNetwork>
#include <QDebug>

class QTcpServer;

QT_BEGIN_NAMESPACE
namespace Ui { class TcpServerDialog; }
QT_END_NAMESPACE

class TcpServerDialog : public QDialog
{
    Q_OBJECT

public:
    TcpServerDialog(QWidget *parent = nullptr);
    ~TcpServerDialog();

private slots:
    void sendMessage();

private:
    Ui::TcpServerDialog *ui;
    QTcpServer *tcpServer;
};
#endif // TCPSERVERDIALOG_H

#include "tcpserverdialog.h"
#include "ui_tcpserverdialog.h"

TcpServerDialog::TcpServerDialog(QWidget *parent)
    : QDialog(parent)
    , ui(new Ui::TcpServerDialog)
{
    ui->setupUi(this);

    tcpServer = new QTcpServer(this);
    //QHostAddress::LocalHost 等价于QHostAddress("127.0.0.1")
    if(!tcpServer->listen(QHostAddress::LocalHost, 6666)){
        qDebug() << tcpServer->errorString();
        close();
    }
    connect(tcpServer, &QTcpServer::newConnection,
            this, &TcpServerDialog::sendMessage);

}

TcpServerDialog::~TcpServerDialog()
{
    delete ui;
}

void TcpServerDialog::sendMessage()
{
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);
    out.setVersion(QDataStream::Qt_5_9);
    out << (quint16)0;
    out << tr("hello tcp!");
    out.device()->seek(0);
    out << (quint16)(block.size() - sizeof(quint16));

    QTcpSocket *clientConnection = tcpServer->nextPendingConnection();
    connect(clientConnection, &QTcpSocket::disconnected,
            clientConnection, &QTcpSocket::deleteLater);
    clientConnection->write(block);
    clientConnection->disconnectFromHost();
    ui->label->setText(tr("发送数据成功了！"));

}