Qt TCP网络上位机的设计（通过网络编程与下位机结合）

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TCP 协议基础

QTcpServer 和 QAbstractSocket 主要接口函数

TCP 应用程序

1.服务端

2.客户端

上位机通过网络编程与下位机实现通信

TCP 协议基础

传输控制协议（TCP，Transmission Control Protocol）是一种面向连接的、可靠的、基于字节流的传输层通信协议

TCP 的拥塞控制算法（也称 AIMD 算法）。该算法主要包括四个主要部分：慢启动、拥塞避免、快速重传和快速恢复

TCP 通信必须建立 TCP 连接（客户端和服务器端），Qt 提供 QTcpSocket 类和 QTcpServer 类专门用于建立 TCP 通信程序。服务器端用 QTcpServer 监听端口及建立服务器；QTcpSocket 用于建立连接后使用套接字(socket)进行通信

QTcpServer 和 QAbstractSocket 主要接口函数

QTcpServer 是从 QOjbect 继承的类用于服务器建立网络监听，创建网络 socket 连接。QTcpServer 主要接口函数如下：

QAbstractSocket主要接口函数如下：

TCP 应用程序

1.服务端

UI绘图：

代码示例：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>#include <QTcpServer> // 专门用于建立TCP连接并传输数据信息
#include <QtNetwork> // 此模块提供开发TCP/IP客户端和服务器的类QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:Ui::MainWindow *ui;// 自定义如下
private:QTcpServer *tcpserver; //TCP服务器QTcpSocket *tcpsocket;// TCP通讯socketQString GetLocalIpAddress(); // 获取本机的IP地址private slots:void clientconnect();void clientdisconnect();void socketreaddata();void newconnection();void on_pushButton_Start_clicked();void on_pushButton_Stop_clicked();void on_pushButton_Send_clicked();protected:void closeEvent(QCloseEvent *event);};
#endif // MAINWINDOW_H

main.cpp

#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);MainWindow w;w.show();return a.exec();
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"#include <QMessageBox>MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);QString strip=GetLocalIpAddress();// QMessageBox::information(this,"数据",strip,QMessageBox::Yes);ui->comboBoxIp->addItem(strip);tcpserver=new QTcpServer(this);connect(tcpserver,SIGNAL(newConnection()),this,SLOT(newconnection()));}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::on_pushButton_Start_clicked()
{QString ip=ui->comboBoxIp->currentText();quint16 port=ui->spinBoxPort->value();QHostAddress address(ip);tcpserver->listen(address,port);ui->plainTextEdit_DispMsg->appendPlainText("$$$$$$$$$$开始监听$$$$$$$$$$");ui->plainTextEdit_DispMsg->appendPlainText("$$$$$$$$$$服务器地址$$$$$$$$$$："+tcpserver->serverAddress().toString());ui->plainTextEdit_DispMsg->appendPlainText("$$$$$$$$$$服务器端口$$$$$$$$$$："+QString::number(tcpserver->serverPort()));ui->pushButton_Start->setEnabled(false);ui->pushButton_Stop->setEnabled(true);}void MainWindow::on_pushButton_Stop_clicked()
{if(tcpserver->isListening()){tcpserver->close();ui->pushButton_Start->setEnabled(true);ui->pushButton_Stop->setEnabled(false);}}void MainWindow::on_pushButton_Send_clicked()
{QString strmsg=ui->lineEdit_InputMsg->text();ui->plainTextEdit_DispMsg->appendPlainText("[out]:"+strmsg);ui->lineEdit_InputMsg->clear();QByteArray str=strmsg.toUtf8();str.append("\n");tcpsocket->write(str);
}QString MainWindow::GetLocalIpAddress() // 获取本机的IP地址
{QString hostname=QHostInfo::localHostName();QHostInfo hostinfo=QHostInfo::fromName(hostname);QString localip="";QList<QHostAddress> addresslist=hostinfo.addresses();if(!addresslist.isEmpty()){for (int i=0;i<addresslist.count();i++){QHostAddress addrhost=addresslist.at(i);if(QAbstractSocket::IPv4Protocol==addrhost.protocol()){localip=addrhost.toString();break;}}}return localip;
}void MainWindow::clientconnect()
{// 客户端连接ui->plainTextEdit_DispMsg->appendPlainText("**********客户端socket连接**********");ui->plainTextEdit_DispMsg->appendPlainText("**********peer address:"+tcpsocket->peerAddress().toString());ui->plainTextEdit_DispMsg->appendPlainText("**********peer port:"+QString::number(tcpsocket->peerPort()));}void MainWindow::clientdisconnect()
{// 客户端断开连接ui->plainTextEdit_DispMsg->appendPlainText("**********客户端socket断开连接**********");tcpsocket->deleteLater();}void MainWindow::socketreaddata()
{// 读取数据while(tcpsocket->canReadLine())ui->plainTextEdit_DispMsg->appendPlainText("[in]"+tcpsocket->readLine());}void MainWindow::newconnection()
{tcpsocket=tcpserver->nextPendingConnection();connect(tcpsocket,SIGNAL(connected()),this,SLOT(clientconnect()));clientconnect();connect(tcpsocket,SIGNAL(disconnected()),this,SLOT(clientdisconnect()));connect(tcpsocket,SIGNAL(readyRead()),this,SLOT(socketreaddata()));connect(tcpsocket,SIGNAL(stateChanged(QAbstractSocket::SocketState)),this,SLOT(OnSocketStateChanged(QAbstractSocket::SocketState)));}void MainWindow::closeEvent(QCloseEvent *event)
{if(tcpserver->isListening())tcpserver->close();event->accept();
}

2.客户端

UI绘图：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>#include <QTcpSocket>
#include <QHostAddress>
#include <QHostInfo>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private:Ui::MainWindow *ui;private:QTcpSocket *tcpclient; // 客户端tcpclientQString getlocalip(); // 获取本机IP地址protected:void closeEvent(QCloseEvent *event);private slots:void connectfunc();void disconnectfunc();void socketreaddata();void on_pushButton_Connect_clicked();void on_pushButton_Send_clicked();void on_pushButton_Disconnect_clicked();
};
#endif // MAINWINDOW_H

main.cpp

#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);MainWindow w;w.show();return a.exec();
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);tcpclient=new QTcpSocket(this);QString strip=getlocalip();ui->comboBoxIp->addItem(strip);connect(tcpclient,SIGNAL(connected()),this,SLOT(connectfunc()));connect(tcpclient,SIGNAL(disconnected()),this,SLOT(disconnectfunc()));connect(tcpclient,SIGNAL(readyRead()),this,SLOT(socketreaddata()));}MainWindow::~MainWindow()
{delete ui;
}void MainWindow::on_pushButton_Connect_clicked()
{QString addr=ui->comboBoxIp->currentText();quint16 port=ui->spinBoxPort->value();tcpclient->connectToHost(addr,port);
}void MainWindow::on_pushButton_Send_clicked()
{QString strmsg=ui->lineEdit_InputMsg->text();ui->plainTextEdit_DispMsg->appendPlainText("[out]:"+strmsg);ui->lineEdit_InputMsg->clear();QByteArray str=strmsg.toUtf8();str.append('\n');tcpclient->write(str);}void MainWindow::on_pushButton_Disconnect_clicked()
{if(tcpclient->state()==QAbstractSocket::ConnectedState)tcpclient->disconnectFromHost();
}QString MainWindow::getlocalip() // 获取本机IP地址
{QString hostname=QHostInfo::localHostName();QHostInfo hostinfo=QHostInfo::fromName(hostname);QString localip="";QList<QHostAddress> addlist=hostinfo.addresses();if(!addlist.isEmpty()){for (int i=0;i<addlist.count();i++){QHostAddress ahost=addlist.at(i);if(QAbstractSocket::IPv4Protocol==ahost.protocol()){localip=ahost.toString();break;}}}return localip;
}void MainWindow::closeEvent(QCloseEvent *event)
{if(tcpclient->state()==QAbstractSocket::ConnectedState){tcpclient->disconnectFromHost();}event->accept();}void MainWindow::connectfunc()
{ui->plainTextEdit_DispMsg->appendPlainText("**********已经连接到服务器端**********");ui->plainTextEdit_DispMsg->appendPlainText("**********peer address:"+tcpclient->peerAddress().toString());ui->plainTextEdit_DispMsg->appendPlainText("**********peer port:"+QString::number(tcpclient->peerPort()));ui->pushButton_Connect->setEnabled(false);ui->pushButton_Disconnect->setEnabled(true);}
void MainWindow::disconnectfunc()
{ui->plainTextEdit_DispMsg->appendPlainText("**********已断开与服务器端的连接**********");ui->pushButton_Connect->setEnabled(true);ui->pushButton_Disconnect->setEnabled(false);}
void MainWindow::socketreaddata()
{while(tcpclient->canReadLine())ui->plainTextEdit_DispMsg->appendPlainText("[in]:"+tcpclient->readLine());}