Qt实现TCP客户端和服务器通讯程序

复习的心态过一遍之前基础的一些东西，Qt封装了QTcpServer和QTcpSocket两个类，其中QTcpServer继承自QObject，通过listen()函数监听传入的客户端连接，当Clien...

复习的心态过一遍之前基础的一些东西，Qt封装了QTcpServer和QTcpSocket两个类，其中QTcpServer继承自QObject，通过listen()函数监听传入的客户端连接，当Client连接上时，QTcpServer会发出newConnection的信号，在对应的槽函数中使用nextPendingConnection()拿到连接的客户端的句柄和信息。

而QTcpSocket则是读写数据的时候使用，过程很简单。

服务器流程：listen->newConnection->nextPendingConnection->readAll/write

客户端流程：connectToHost->waitForConnected->write/readAll

需要注意的是在使用网络相关的类前，需要在pro文件加上QT += network

通信时：

客户端掉线时：

QTcpServer服务器代码（包含.h和.cpp）:

.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTcpServer>
#include <QTcpSocket>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
  Q_OBJECT

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

protected slots:
  void onSendBtnClicked();
  void onNewClientConnected();
  void onRecvData();
  void onClientDisconnected();

private:
  void Init();

private:
  Ui::Widget *ui;

private:
  QTcpServer *_tcpServer;
  QTcpSocket *_tcpSocket;
};
#endif // WIDGET_H

.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QHostAddress>
#include <QDebug>

#define MyTcpPort 8886

Widget::Widget(QWidget *parent)
  : QWidget(parent)
  , ui(new Ui::Widget)
  ,_tcpServer(nullptr)
  ,_tcpSocket(nullptr)
{
  ui->setupUi(this);

  connect(this->ui->btn_send,&QPushButton::clicked,this,&Widget::onSendBtnClicked);

  Init();

  setWindowTitle("服务端");
}

Widget::~Widget()
{
  delete ui;

  if(_tcpSocket)
  {
    _tcpSocket->disconnect();
    _tcpSocket编程->abort();
    _tcpSocket->close();
    _tcpSocket->deleteLater();
  }
  if(_tcpServer)
  {
    _tcpServer->close();
    delete _tcpServer;
  }
}

void Widget::Init()
{
  _tcpSocket = new QTcpSocket;
  _tcpServer = new QTcpServer;

  int ret = _tcpServer->listen(QHostAddress::AnyIPv4,MyTcpPort);
  if(ret==0)
  {
    qDebug()<<"_tcpServer->listen is failied";
    return;
  }
  connect(_tcpServer,&QTcpServer::newConnection,this,&Widget::onNewClientConnected);
}

void Widget::onSendBtnClicked()
{
  if(!_tcpSocket) return;

  QString inputText = ui->inputEdit->text();
  if(inputText.isEmpty())
    return;
  //发送数据
  int ret = _tcpSocket->write(inputText.toStdString().c_str());
  if(ret<0)
  {
    qDebug()<<"write to client http://www.cppcns.comis failed!";
  }
}

void Widget::onNewClientConnected()
{
  if(_tcpServer->hASPendingConnections())
  {
    _tcpSocket = _tcpServer->nextPendingConnection();
    if(!_tcpSocket->isValid()) return;
    connect(_tcpSocket,&QTcpSocket::readyRead,this,
        &Widget::onRecvData);
    connect(_tcpSocket,&QTcpSocket::disconnected,this,
        &Widget::onClientDisconnected);
  }
}

void Widget::onRecvData()
{
  if(!_tcpSocket) return;
  QString recvData=_tcpSocket->readAll();
  qDebug()<<"recvData:"<<recvData;

  this->ui->recvEdit->append(recvData);
}

void Widget::onClientDisconnected()
{
  QString clientIp = _tcpSocket->peerAddress().toString();
  this->ui->recvEdit->append(clientIp+" is Drop line!");
}

QTcpClient客户端代码（包含.h和.cpp）:

/.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTcpSocket>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
  Q_OBJECT

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

private:
  void Init();

protected slots:
  void onSendBtnClicked();
  void onRecvData();

private:
  Ui::Widget *ui;

private:
  QTcpSocket *_tcpClient;
};
#endif // WIDGET_H

/.cpp
#include "widget.h"
#include "ui_widget.h"

#define MyTcpPort 8886

Widget::Widget(QWidget *parent)
  : QWidget(parent)
  , ui(new Ui::Widget),_tcpClient(nullptr)
{
  ui->setupUi(this);

  connect(this->ui->btn_send,&QPushButton::clicked,this,&Widget::onSendBtnClicked);

  Init();

  setWindowTitle("客户端");
}

Widget::~Widget()
{
  delete ui;

  if(_tcpClient)
  {
    _tcpClient->close();
    _tcpClient->deleteLater();
  }
}

void Widget::Init()
{
  _tcpClient=new QTcpSocket;
  _tcpClient->abort();
  _tcpClient->connectToHost("127.0.0.1",MyTcpPort);
  iAqarAuHqlcf(!_tcpClient->waitForConnected(2000))
  {
    qDebug()<<"connect is failed!";
    return;
  }
  qDebug()<<"connect is successful";
  connect(_tcpClient,&QTcpSocket::readyRead,this,&Widget::onRecvData);
}

void Widget::onSendBtnClicked()
{
  if(!_tcpClient) return;

  QString wStr=ui->inputEdit->text();

  int ret = _tcpClient->write(wStr.toStdString().c_str());
  if(ret<0)
  {
    qDebug()<<"send data is failed";
  }
  qDebug()<<"send data is successful!";
}

void Widget::onRecvData()
{
  if(!_tcpClient) return;

  QString recvData= _tcpClient->readAll();
  ui->recvEdit->append(recvData);
  qDebug()<<"recvData:"<<recvData;
}

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