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_NAMESPACE class MainWindow : public QMainWindow { Q_OBJECT public: 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socket QString 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_NAMESPACE class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = nullptr); ~MainWindow(); private: Ui::MainWindow *ui; private: QTcpSocket *tcpclient; // 客户端tcpclient QString 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()); }
上位机通过网络编程与下位机实现通信
Qt作为上位机
51、32单片机或ARM开发板开作为下位机
通过网络编程实现通信
上位机可作为服务端或客户端，下位机也可作为服务端或客户端，具体按各自的项目需求实现
