C++/Qt/QTcpSocket

QTcpSocket based client

<source lang="cpp">

1. ifndef CLIENT_H
2. define CLIENT_H
3. include <QDialog>
4. include <QTcpSocket>

QT_BEGIN_NAMESPACE class QDialogButtonBox; class QLabel; class QLineEdit; class QPushButton; class QTcpSocket; QT_END_NAMESPACE class Client : public QDialog {

   Q_OBJECT

public:

   Client(QWidget *parent = 0);

private slots:

   void requestNewFortune();
   void readFortune();
   void displayError(QAbstractSocket::SocketError socketError);
   void enableGetFortuneButton();

private:

   QLabel *hostLabel;
   QLabel *portLabel;
   QLineEdit *hostLineEdit;
   QLineEdit *portLineEdit;
   QLabel *statusLabel;
   QPushButton *getFortuneButton;
   QPushButton *quitButton;
   QDialogButtonBox *buttonBox;
   QTcpSocket *tcpSocket;
   QString currentFortune;
   quint16 blockSize;

};

1. endif

1. include <QtGui>
2. include <QtNetwork>
3. include "client.h"

Client::Client(QWidget *parent): QDialog(parent) {

   hostLabel = new QLabel(tr("&Server name:"));
   portLabel = new QLabel(tr("S&erver port:"));
   hostLineEdit = new QLineEdit("Localhost");
   portLineEdit = new QLineEdit;
   portLineEdit->setValidator(new QIntValidator(1, 65535, this));
   hostLabel->setBuddy(hostLineEdit);
   portLabel->setBuddy(portLineEdit);
   statusLabel = new QLabel(tr("This examples requires that you run the "
                               "Fortune Server example as well."));
   getFortuneButton = new QPushButton(tr("Get Fortune"));
   getFortuneButton->setDefault(true);
   getFortuneButton->setEnabled(false);
   quitButton = new QPushButton(tr("Quit"));
   buttonBox = new QDialogButtonBox;
   buttonBox->addButton(getFortuneButton, QDialogButtonBox::ActionRole);
   buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

   tcpSocket = new QTcpSocket(this);
   connect(hostLineEdit, SIGNAL(textChanged(const QString &)),this, SLOT(enableGetFortuneButton()));
   connect(portLineEdit, SIGNAL(textChanged(const QString &)),this, SLOT(enableGetFortuneButton()));
   connect(getFortuneButton, SIGNAL(clicked()),this, SLOT(requestNewFortune()));
   connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
   connect(tcpSocket, SIGNAL(readyRead()), this, SLOT(readFortune()));
   connect(tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),this, SLOT(displayError(QAbstractSocket::SocketError)));
   QGridLayout *mainLayout = new QGridLayout;
   mainLayout->addWidget(hostLabel, 0, 0);
   mainLayout->addWidget(hostLineEdit, 0, 1);
   mainLayout->addWidget(portLabel, 1, 0);
   mainLayout->addWidget(portLineEdit, 1, 1);
   mainLayout->addWidget(statusLabel, 2, 0, 1, 2);
   mainLayout->addWidget(buttonBox, 3, 0, 1, 2);
   setLayout(mainLayout);
   setWindowTitle(tr("Fortune Client"));
   portLineEdit->setFocus();

} void Client::requestNewFortune() {

   getFortuneButton->setEnabled(false);
   blockSize = 0;
   tcpSocket->abort();
   tcpSocket->connectToHost(hostLineEdit->text(),
                            portLineEdit->text().toInt());

} void Client::readFortune() {

   QDataStream in(tcpSocket);
   in.setVersion(QDataStream::Qt_4_0);
   if (blockSize == 0) {
       if (tcpSocket->bytesAvailable() < (int)sizeof(quint16))
           return;
       in >> blockSize;
   }
   if (tcpSocket->bytesAvailable() < blockSize)
       return;
   QString nextFortune;
   in >> nextFortune;
   if (nextFortune == currentFortune) {
       QTimer::singleShot(0, this, SLOT(requestNewFortune()));
       return;
   }
   currentFortune = nextFortune;
   statusLabel->setText(currentFortune);
   getFortuneButton->setEnabled(true);

} void Client::displayError(QAbstractSocket::SocketError socketError) {

   switch (socketError) {
   case QAbstractSocket::RemoteHostClosedError:
       break;
   case QAbstractSocket::HostNotFoundError:
       QMessageBox::information(this, tr("Fortune Client"),
                                tr("The host was not found. Please check the "
                                   "host name and port settings."));
       break;
   case QAbstractSocket::ConnectionRefusedError:
       QMessageBox::information(this, tr("Fortune Client"),
                                tr("The connection was refused by the peer. "
                                   "Make sure the fortune server is running, "
                                   "and check that the host name and port "
                                   "settings are correct."));
       break;
   default:
       QMessageBox::information(this, tr("Fortune Client"),
                                tr("The following error occurred: %1.")
                                .arg(tcpSocket->errorString()));
   }
   getFortuneButton->setEnabled(true);

} void Client::enableGetFortuneButton(){

   getFortuneButton->setEnabled(!hostLineEdit->text().isEmpty()
                                && !portLineEdit->text().isEmpty());

}

1. include <QApplication>
2. include "client.h"

int main(int argc, char *argv[]) {

   QApplication app(argc, argv);
   Client client;
   client.show();
   return client.exec();

}

 </source>