【QT】TCPClient客户端实例 QT学习笔记

【【QT】TCPClient客户端实例】TCPClient客户端实现功能：
（1）通过IP地址和端口号连接到服务器；
（2）采用基于行的数据通信协议，与服务器端收发消息；
（3）处理QTcpSocket的StateChange()信号，在状态栏显示socket的状态。

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1 .pro文件添加

QT += network

2 .h文件

#ifndef MAINWINDOW_H #define MAINWINDOW_H#include #include #include #include namespace Ui { class MainWindow; }class MainWindow : public QMainWindow { Q_OBJECT private: QTcpSocket *tcpClient; //TCP通信socket QLabel *labSocketState; //socket状态标签 QString getLocalIP(); //获取本地IPprotected: void closeEvent(QCloseEvent *e); public: explicit MainWindow(QWidget *parent = nullptr); ~MainWindow(); private slots: void on_actConnected_triggered(); void on_actDisconnected_triggered(); void on_actClear_triggered(); void on_actExit_triggered(); void on_btnSend_clicked(); void onConnected(); //connected()信号槽函数 void onDisconnected(); //disconnected()信号槽函数 void onSocketStateChange(QAbstractSocket::SocketState socketState); //socketStateChange()信号槽函数，显示socket状态的变化 void onSocketReadyRead(); //readyRead()信号槽函数，读取数据private: Ui::MainWindow *ui; }; #endif // MAINWINDOW_H

3 .cpp文件

#include "mainwindow.h" #include "ui_mainwindow.h"#include MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); tcpClient = new QTcpSocket(this); labSocketState = new QLabel("Socket 状态："); //socket状态标签 labSocketState->setMinimumWidth(250); ui->statusBar->addWidget(labSocketState); QString localIP = getLocalIP(); //获取本地IP this->setWindowTitle(this->windowTitle() + "----本机IP：" + localIP); //设置窗口标题ui->cbbAddress->addItem(localIP); ui->actConnected->setEnabled(true); ui->actDisconnected->setEnabled(false); connect(tcpClient, &QTcpSocket::connected, this, &MainWindow::onConnected); connect(tcpClient, &QTcpSocket::disconnected,this, &MainWindow::onDisconnected); connect(tcpClient, &QTcpSocket::stateChanged, this, &MainWindow::onSocketStateChange); connect(tcpClient, &QTcpSocket::readyRead, this, &MainWindow::onSocketReadyRead); }MainWindow::~MainWindow() { delete ui; }void MainWindow::on_actConnected_triggered() { QString addr = ui->cbbAddress->currentText(); quint16 port = ui->spinPort->value(); tcpClient->connectToHost(addr, port); //连接到服务器 }void MainWindow::on_actDisconnected_triggered() { if(tcpClient->state() == QAbstractSocket::ConnectedState) tcpClient->disconnectFromHost(); //与服务器断开连接 }void MainWindow::on_actClear_triggered() { ui->plainTextEdit->clear(); }void MainWindow::on_actExit_triggered() { this->close(); }void MainWindow::on_btnSend_clicked() { QString msg = ui->editMessage->text(); //获取发送数据 ui->plainTextEdit->appendPlainText("[out] " + msg); ui->editMessage->clear(); ui->editMessage->setFocus(); QByteArray str = msg.toUtf8(); str.append('\n'); tcpClient->write(str); //数据发送 }void MainWindow::onConnected() { ui->plainTextEdit->appendPlainText("**已连接到服务器"); ui->plainTextEdit->appendPlainText("**peer address:" + tcpClient->peerAddress().toString()); ui->plainTextEdit->appendPlainText("**peer port:" + QString::number(tcpClient->peerPort())); ui->actConnected->setEnabled(false); ui->actDisconnected->setEnabled(true); }void MainWindow::onDisconnected() { ui->plainTextEdit->appendPlainText("**已断开与服务器的连接"); ui->actConnected->setEnabled(true); ui->actDisconnected->setEnabled(false); }void MainWindow::onSocketStateChange(QAbstractSocket::SocketState socketState) { switch(socketState)//显示socket状态变化 { case QAbstractSocket::UnconnectedState: labSocketState->setText("socket状态：UnconnectedState"); break; case QAbstractSocket::HostLookupState: labSocketState->setText("socket状态：HostLookupState"); break; case QAbstractSocket::ConnectingState: labSocketState->setText("socket状态：ConnectingState"); break; case QAbstractSocket::ConnectedState: labSocketState->setText("socket状态：ConnectedState"); break; case QAbstractSocket::BoundState: labSocketState->setText("socket状态：BoundState"); break; case QAbstractSocket::ClosingState: labSocketState->setText("socket状态：ClosingState"); break; case QAbstractSocket::ListeningState: labSocketState->setText("socket状态：ListeningState"); } }void MainWindow::onSocketReadyRead() { while(tcpClient->canReadLine())//读取数据，以一整行的方式读取 ui->plainTextEdit->appendPlainText("[in] " + tcpClient->readLine()); }QString MainWindow::getLocalIP() { QString hostName = QHostInfo::localHostName(); QHostInfo hostInfo = QHostInfo::fromName(hostName); QString localIP = ""; QList 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 *e) { if(tcpClient->state() == QAbstractSocket::ConnectedState)//关闭时，确保与服务器断开连接 tcpClient->disconnectFromHost(); e->accept(); }

学习书籍：《Qt5.9 C++开发指南》