How to realize instant communication in C/S architecture under Qt network programming Tcp

Write a client interface first

Implement a simple interface that can join the chat and join the server.

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#ifndef TCPCLIENT_H
#define TCPCLIENT_H
 
#include <QDialog>
#include <QListWidget>
#include <QLineEdit>
#include <QPushButton>
#include <QLabel>
#include <QGridLayout>
#include <QtNetWork/QHostAddress>
#include <QtNetWork/QTcpSocket>
 
class TcpClient : public QDialog
{
 Q_OBJECT
 
public:
 TcpClient(QWidget *parent = 0,Qt::WindowFlags f=0);
 ~TcpClient();
private:
 QListWidget *contentListWidget;
 QLineEdit *sendLineEdit;
 QPushButton *sendBtn;
 QLabel *userNameLabel;
 QLineEdit *userNameLineEdit;
 QLabel *serverIPLabel;
 QLineEdit *serverIPLineEdit;
 QLabel *portLabel;
 QLineEdit *portLineEdit;
 QPushButton *enterBtn;
 QGridLayout *mainLayout;
 bool status;
 int port;
 QHostAddress *serverIP;
 QString userName;
 QTcpSocket *tcpSocket;
public slots:
 void slotEnter();
 void slotConnected();
 void slotDisconnected();
 void dataReceived();
 void slotSend();
};
 
#endif // TCPCLIENT_H

There is a button to join the server and a button to send a message. In the header file, first define two functions.

#include "tcpclient.h"
#include <QMessageBox>
#include <QHostInfo>
 
TcpClient::TcpClient(QWidget *parent,Qt::WindowFlags f)
 : QDialog(parent,f)
{
 setWindowTitle(tr("TCP Client"));
 
 contentListWidget = new QListWidget;
 
 sendLineEdit = new QLineEdit;
 sendBtn = new QPushButton(tr("send"));
 
 userNameLabel = new QLabel(tr("name"));
 userNameLineEdit = new QLineEdit;
 
 serverIPLabel = new QLabel(tr("server"));
 serverIPLineEdit = new QLineEdit;
 
 portLabel = new QLabel(tr("port"));
 portLineEdit = new QLineEdit;
 
 enterBtn= new QPushButton(tr("join chat"));
 
 mainLayout = new QGridLayout(this);
 mainLayout->addWidget(contentListWidget,0,0,1,2);
 mainLayout->addWidget(sendLineEdit,1,0);
 mainLayout->addWidget(sendBtn,1,1);
 mainLayout->addWidget(userNameLabel,2,0);
 mainLayout->addWidget(userNameLineEdit,2,1);
 mainLayout->addWidget(serverIPLabel,3,0);
 mainLayout->addWidget(serverIPLineEdit,3,1);
 mainLayout->addWidget(portLabel,4,0);
 mainLayout->addWidget(portLineEdit,4,1);
 mainLayout->addWidget(enterBtn,5,0,1,2);
 
 status = false;
 
 port = 8010;
 portLineEdit->setText(QString::number(port));
 
 serverIP =new QHostAddress();
 
 connect(enterBtn,SIGNAL(clicked()),this,SLOT(slotEnter()));
 connect(sendBtn,SIGNAL(clicked()),this,SLOT(slotSend()));
 
 sendBtn->setEnabled(false);
}
 
TcpClient::~TcpClient()
{
 
}
 
void TcpClient::slotEnter()
{
 if(!status)
 {
  QString ip = serverIPLineEdit->text();
  if(!serverIP->setAddress(ip))
  {
   QMessageBox::information(this,tr("error"),tr("server ip address error!"));
   return;
  }
 
  if(userNameLineEdit->text()=="")
  {
   QMessageBox::information(this,tr("error"),tr("User name error!"));
   return;
  }
 
  userName=userNameLineEdit->text();
 
  tcpSocket = new QTcpSocket(this);
  connect(tcpSocket,SIGNAL(connected()),this,SLOT(slotConnected()));
  connect(tcpSocket,SIGNAL(disconnected()),this,SLOT(slotDisconnected()));
  connect(tcpSocket,SIGNAL(readyRead()),this,SLOT(dataReceived()));
 
  tcpSocket->connectToHost(*serverIP,port);
 
  status=true;
 }
 else
 {
  int length=0;
  QString msg=userName+tr(":Leave Chat Room");
  if((length=tcpSocket->write(msg.toLatin1(),msg.length()))!=msg. length())
  {
   return;
  }
 
  tcpSocket->disconnectFromHost();
 
  status=false;
 }
}
 
void TcpClient::slotConnected()
{
 sendBtn->setEnabled(true);
 enterBtn->setText(tr("离开"));
 
 int length=0;
 QString msg=userName+tr(":Enter Chat Room");
 if((length=tcpSocket->write(msg.toLatin1(),msg.length()))!=msg.length())
 {
  return;
 }
}
 
void TcpClient::slotSend()
{
 if(sendLineEdit->text()=="")
 {
  return ;
 }
 
 QString msg=userName+":"+sendLineEdit->text();
 
 tcpSocket->write(msg.toLatin1(),msg.length());
 sendLineEdit->clear();
}
 
void TcpClient::slotDisconnected()
{
 sendBtn->setEnabled(false);
 enterBtn->setText(tr("join chat"));
}
 
void TcpClient::dataReceived()
{
 while(tcpSocket->bytesAvailable()>0)
 {
  QByteArray datagram;
  datagram.resize(tcpSocket->bytesAvailable());
 
  tcpSocket->read(datagram.data(),datagram.size());
 
  QString msg=datagram.data();
  contentListWidget->addItem(msg.left(datagram.size()));
 }
}

Realize interface layout. In the Enter slot function, the function of determining whether to join or leave the server. If it joins, write the message to tcpsocket and construct a message.

Server header file:

#ifndef TCPSERVER_H
#define TCPSERVER_H
 
#include <QDialog>
#include <QListWidget>
#include <QLabel>
#include <QLineEdit>
#include <QPushButton>
#include <QGridLayout>
#include "server.h"
 
class TcpServer : public QDialog
{
 Q_OBJECT
 
public:
 TcpServer(QWidget *parent = 0,Qt::WindowFlags f=0);
 ~TcpServer();
private:
 QListWidget *ContentListWidget;
 QLabel *PortLabel;
 QLineEdit *PortLineEdit;
 QPushButton *CreateBtn;
 QGridLayout *mainLayout;
 int port;
 Server *server;
public slots:
 void slotCreateServer();
 void updateServer(QString,int);
};
 
#endif // TCPSERVER_H

This is the interface of the server, just to display the message. implement this layout.

#include "tcpserver.h"
 
TcpServer::TcpServer(QWidget *parent,Qt::WindowFlags f)
 : QDialog(parent,f)
{
 setWindowTitle(tr("TCP Server"));
 
 ContentListWidget = new QListWidget;
 
 PortLabel = new QLabel(tr(" port"));
 PortLineEdit = new QLineEdit;
 
 CreateBtn = new QPushButton(tr("create chat"));
 mainLayout = new QGridLayout(this);
 mainLayout->addWidget(ContentListWidget,0,0,1,2);
 mainLayout->addWidget(PortLabel,1,0);
 mainLayout->addWidget(PortLineEdit,1,1);
 mainLayout->addWidget(CreateBtn,2,0,1,2);
 
 port=8010;
 PortLineEdit->setText(QString::number(port));
 
 connect(CreateBtn,SIGNAL(clicked()),this,SLOT(slotCreateServer()));
}
 
TcpServer::~TcpServer()
{
 
}
 
void TcpServer::slotCreateServer()
{
 server = new Server(this,port);
 connect(server,SIGNAL(updateServer(QString,int)),this,SLOT(updateServer(QString,int)));
 
 CreateBtn->setEnabled(false);
}
 
void TcpServer::updateServer(QString msg,int length)
{
 ContentListWidget->addItem(msg.left(length));
}

Create a TCP socket for communication between the server and the client.

#ifndef TCPCLIENTSOCKET_H
#define TCPCLIENTSOCKET_H
 
#include <QtNetWork/QTcpSocket>
#include <QObject>
 
class TcpClientSocket : public QTcpSocket
{
 Q_OBJECT
public:
 TcpClientSocket();
signals:
 void updateClients(QString,int);
 void disconnected(int);
protected slots:
 void dataReceived();
 void slotDisconnected();
};
 
#endif // TCPCLIENTSOCKET_H

The above is the header file, specifically:

#include "tcpclientsocket.h"
 
TcpClientSocket::TcpClientSocket()
{
 connect(this,SIGNAL(readyRead()),this,SLOT(dataReceived()));
 connect(this,SIGNAL(disconnected()),this,SLOT(slotDisconnected()));
}
 
void TcpClientSocket::dataReceived()
{
 while(bytesAvailable()>0)
 {
  int length = bytesAvailable();
  char buf[1024];
  read(buf,length);
 
  QString msg=buf;
  emit updateClients(msg,length);
 }
}
 
void TcpClientSocket::slotDisconnected()
{
 emit disconnected(this->socketDescriptor());
}

Implement the server, the header file:

#ifndef SERVER_H
#define SERVER_H
 
#include <QtNetWork/QTcpServer>
#include <QObject>
#include "tcpclientsocket.h"
 
class Server : public QTcpServer
{
 Q_OBJECT
public:
 Server(QObject *parent=0,int port=0);
 QList<TcpClientSocket*> tcpClientSocketList;
signals:
 void updateServer(QString,int);
public slots:
 void updateClients(QString,int);
 void slotDisconnected(int);
protected:
 void incomingConnection(int socketDescriptor);
};
 
#endif // SERVER_H

#include "server.h"
 
Server::Server(QObject *parent,int port)
 :QTcpServer(parent)
{
 listen(QHostAddress::Any,port);
}
 
void Server::incomingConnection(int socketDescriptor)
{
 TcpClientSocket *tcpClientSocket = new TcpClientSocket;
 connect(tcpClientSocket,SIGNAL(updateClients(QString,int)),this,SLOT(updateClients(QString,int)));
 connect(tcpClientSocket,SIGNAL(disconnected(int)),this,SLOT(slotDisconnected(int)));
 
 tcpClientSocket->setSocketDescriptor(socketDescriptor);
 
 tcpClientSocketList.append(tcpClientSocket);
}
 
void Server::updateClients(QString msg,int length)
{
 emit updateServer(msg,length);
 for(int i=0;i<tcpClientSocketList.count();i++)
 {
  QTcpSocket *item = tcpClientSocketList.at(i);
  if(item->write(msg.toLatin1(),length)!=length)
  {
   continue;
  }
 }
}
 
void Server::slotDisconnected(int descriptor)
{
 for(int i=0;i<tcpClientSocketList.count();i++)
 {
  QTcpSocket *item = tcpClientSocketList.at(i);
  if(item->socketDescriptor()==descriptor)
  {
   tcpClientSocketList.removeAt(i);
   return;
  }
 }
 return;
}

Implemented interface:

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