//main.cpp
#include <QApplication>
#include "MyClient.h"

int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    MyClient     client("localhost", 2323);

    client.show();

    return app.exec();
}

// MyClient.cpp

#include <QTcpSocket>
#include "MyClient.h"

MyClient::MyClient(const QString& strHost,
                   int            nPort,
                   QWidget*       pwgt /*=0*/
                  ) : QWidget(pwgt)
                    , m_nNextBlockSize(0)
{
    m_pTcpSocket = new QTcpSocket(this);

    m_pTcpSocket->connectToHost(strHost, nPort);
    connect(m_pTcpSocket, SIGNAL(connected()), SLOT(slotConnected()));
    connect(m_pTcpSocket, SIGNAL(readyRead()), SLOT(slotReadyRead()));
    connect(m_pTcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
            this,         SLOT(slotError(QAbstractSocket::SocketError))
           );

    m_ptxtInfo  = new QTextEdit;
    m_ptxtInput = new QLineEdit;

    connect(m_ptxtInput, SIGNAL(returnPressed()),
            this,        SLOT(slotSendToServer())
           );
    m_ptxtInfo->setReadOnly(true);

    QPushButton* pcmd = new QPushButton("&Send");
    connect(pcmd, SIGNAL(clicked()), SLOT(slotSendToServer()));

    //Layout setup
    QVBoxLayout* pvbxLayout = new QVBoxLayout;
    pvbxLayout->addWidget(new QLabel("<H1>Client</H1>"));
    pvbxLayout->addWidget(m_ptxtInfo);
    pvbxLayout->addWidget(m_ptxtInput);
    pvbxLayout->addWidget(pcmd);
    setLayout(pvbxLayout);
}

void MyClient::slotReadyRead()
{
    QDataStream in(m_pTcpSocket);
    in.setVersion(QDataStream::Qt_4_2);
    for (;;) {
        if (!m_nNextBlockSize) {
            if (m_pTcpSocket->bytesAvailable() < sizeof(quint16)) {
                break;
            }
            in >> m_nNextBlockSize;
        }

        if (m_pTcpSocket->bytesAvailable() < m_nNextBlockSize) {
            break;
        }
        QTime   time;
        QString str;
        in >> time >> str;

        m_ptxtInfo->append(time.toString() + " " + str);
        m_nNextBlockSize = 0;
    }
}

void MyClient::slotError(QAbstractSocket::SocketError err)
{
    QString strError =
        "Error: " + (err == QAbstractSocket::HostNotFoundError ?
                     "The host was not found." :
                     err == QAbstractSocket::RemoteHostClosedError ?
                     "The remote host is closed." :
                     err == QAbstractSocket::ConnectionRefusedError ?
                     "The connection was refused." :
                     QString(m_pTcpSocket->errorString())
                    );
    m_ptxtInfo->append(strError);
}
void MyClient::slotSendToServer()
{
    QByteArray  arrBlock;
    QDataStream out(&arrBlock, QIODevice::WriteOnly);
    out.setVersion(QDataStream::Qt_4_2);
    out << quint16(0) << QTime::currentTime() << m_ptxtInput->text();

    out.device()->seek(0);
    out << quint16(arrBlock.size() - sizeof(quint16));

    m_pTcpSocket->write(arrBlock);
    m_ptxtInput->setText("");
}
void MyClient::slotConnected()
{
    m_ptxtInfo->append("Received the connected() signal");
}

//MyClient.h

#ifndef _MyClient_h_
#define _MyClient_h_

#include <QWidget>
#include <QTcpSocket>

class QTextEdit;
class QLineEdit;

class MyClient : public QWidget {
Q_OBJECT
private:
    QTcpSocket* m_pTcpSocket;
    QTextEdit*  m_ptxtInfo;
    QLineEdit*  m_ptxtInput;
    quint16     m_nNextBlockSize;

public:
    MyClient(const QString& strHost, int nPort, QWidget* pwgt = 0) ;

private slots:
    void slotReadyRead   (                            );
    void slotError       (QAbstractSocket::SocketError);
    void slotSendToServer(                            );
    void slotConnected   (                            );
};
#endif  //_MyClient_h_

//MyClient.pro
#-------------------------------------------------
#
# Project created by QtCreator 2015-09-10T09:50:56
#
#-------------------------------------------------

QT       += core gui
QT       += network widgets
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = MyClient
TEMPLATE = app


SOURCES += main.cpp\
        MyClient.cpp

HEADERS  += MyClient.h

FORMS    += MyClient.ui