Qt中TCP协议通信详解

素材狗 2022-09-21 07:45:01 文章分类：C/C++开发点击数：次

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TCP协议是经常使用的通信方式。在QT中做了非常友好的封装，使用非常方便。需要添加的模块：networkQt中的TCP类：QTcpSocket,QTcpServer常用函数介绍连接目标地址和端口v...

TCP协议是经常使用的通信方式。在QT中做了非常友好的封装，使用非常方便。

需要添加的模块：network

Qt中的TCP类：QTcpSocket , QTcpServer

常用函数介绍

连接目标地址和端口

virtual void QTcpSocket ::connectToHost(const QHostAddress &address, quint16 port, OpenMode mode = Readwrite);

发送数据

inline qint64 QTcpSocket ::write(const QByteArray &data)

监听某个地址和端口号

bool QTcpServer::listen(const QHostAddress &address = QHostAddress::Any, quint16 port = 0);

有新的连接信号

void QTcpServer::newConnection();

是否有新的连接

virtual bool QTcpServer::hASPendingConnections() const;

获取新的连接，必须处理完才能继续接收到连接

virtual QTcpSocket *QTcpServer::nextPendingConnection();

收到新的数据信号

void QTcpSocket::readyRead();

读取收到的数据，必须读取完才能继续接收

QByteArray readAll();

使用案例（example）

客户端

#include <QTcpSocket>
#include <QWidget>
#include <QLineEdit>
class Client : public QWidget
{
 Q_OBJECT
public:
 Client(QWidget *parent);

public slots:
 void slotSendButtonClick();
private:
 QTcpSocket *_socket;
 QLineEdit *_lineEdit;
 bool _isConnected;
};

#include "client.h"
#include <QPushButton>
#include <QHBoxLayout>
Client::Client(QWidget *parent)
 : QWidget(parent)
{
 _socket = new QTcpSocket(this);

 _lineEdit = new QLineEdit(this);
 QPushButton *sendButton = new QPushButton("send");
 connect(sendButton, SIGNAL(clicked()), this, SLOT(slotSendButtonClick()));
 connect(_lineEdit, SIGNAL(returnPressed()), this, SLOT(slotSendButtonClick()));
 
 QHBoxLayout *lay = new QHBoxLayout(this);
 lay->addWidget(_lineEdit);
 lay->addWidget(sendButton);

 _isConnected = false;
}

void Client::slotSendButtonClick()
{
 if (!_isConnected)
 {
  _socket->connectToHost("127.0.0.1", 9988);
  _isConnected = true;
 }
 QString text = _lineEdit->text();
 if (!text.isEmpty())
 {
  _socket->write(text.toUtf8());//发送数据
  _lineEdit->clear();
 }
}

服务端

#include <QWidget>
#include <QTcpServer>
#include <QTcpSocket>
class QTextBrowser;
class Server :public QWidget
{
 Q_OBJECT
public:
 Server(QWidget *parent);
public slots:
 void slotCurrentIndexChanged(const QString&);
 void slotNewConnection();
private:
 QTcpServer *_server;
 QTcpSocket *_socket;
 QTextBrowser *_textBrowser;
};

#include "server.h"
#include <QHostAddress>
#include <QTextBrowser>
#include <QByteArray>
#include <QGridLayout>
#include <QNetworkInterface>
#include <QComboBox>
Server::Server(QWidget *parent)
{
 _server = new QTcpServer(this);
 //_server->listen(QHostAddress::Any, 9988);//监听跟本主机相连的所有网口
 connect(_server, SIGNAL(newConnection()),this, SLOT(slotNewConnection()) );

 QList<QHostAddress> addrList = QNetworkInterface::allAddresses();
 QComboBox *comboBox = new QComboBox;
 for (const QHostAddress& addr : addrList)
 {
  quint32 ipAddr = addr.toIPv4Address();
  if (ipAddr != 0)
  {
   comboBox->addItem(QHostAddress(ipAddr).toString());
  }
 }
 connect(comboBox, SIGNAL(currentIndexChanged(const QString&)), this, SLOT(slotCurrentIndexChanged(const QString&)));


 _textBrowser = new QTextBrowser(this);
 QGridLayout *lay = new QGridLayout(this);
 lay->addWidget(comboBox, 0, 0);
 lay->addWidget(_textBrowser,1,0);
}

void Server::slotCurrentIndexChanged(const QString& item)
{
 if (!_server->isListening())
 {
  _server->listen(QHostAddress(item), 9988);
 }
 
 _textBrowser->append("listen...");
}

void Server::slotNewConnection()
{
 _textBrowser->append("connecting...");
 while (_server->hasPendingConnections())//必须处理完所有的连接，否则有新连接时就不会在发信号过来
 {
  _socket = _server->nextPendingConnection();
  connect(_socket, &QTcpSocket::readyRead, [&]() {
   _textBrowser->append("receive message...");
   QByteArray newMessage = _socket->readAll();
   _textBrowser->append(QString(newMessage));
  });
 }
}

使用效果