QT study notes: Implementation of TCP client

QT is generally used as a client. Here I will briefly talk about how to develop a QT-based TCP client.

1. Create a project with QtCreator

2. Interface

3. Add network to .pro file

QT       += core gui network

4、mainwindow.h


#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTcpSocket>


QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private slots:
    // 构造函数中用connect绑定
    void StartConnect();
    void connectSucc();
    void ReadData();
    void disConnect();
    
    // 自动绑定
    void on_send_message_clicked();

private:
    Ui::MainWindow *ui;
    QTcpSocket *tcpsocket;
};

#endif // MAINWINDOW_H

5、mainwindow.cpp


#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    setWindowTitle("客户端");
    resize(800, 700);

    //设置默认的IP地址和端口
    ui->ip->setText("127.0.0.1");
    ui->port->setText("8899");

    tcpsocket = new QTcpSocket(this);

    //开始连接
    connect(ui->connect_bt, SIGNAL(clicked(bool)), this, SLOT(StartConnect()));

    //绑定客户端的连接信号与槽，便于在槽函数中书写逻辑
    connect(tcpsocket, SIGNAL(connected()), this, SLOT(connectSucc()));

    //当服务器端发送消息过来时，客户端接收并出来消息
    connect(tcpsocket, SIGNAL(readyRead()), this, SLOT(ReadData()));

    //断开连接时处理业务
    connect(ui->disconnect_bt, SIGNAL(clicked(bool)), this, SLOT(disConnect()));

    ui->send_message->setEnabled(false);
    ui->disconnect_bt->setEnabled(false);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::StartConnect()
{
    ui->display_message->append("开始连接服务器");

    //主动连接服务器
    tcpsocket->connectToHost(ui->ip->text().trimmed(),ui->port->text().toInt());

    if (ui->display_message->document()->blockCount() > 100){
        ui->display_message->clear();
    }
}

void MainWindow::connectSucc()
{
    if (ui->display_message->document()->blockCount() > 100){
        ui->display_message->clear();
    }
    ui->display_message->append("服务器连接成功！");
    ui->display_message->append("现在可以开始互相发送消息啦！");
    ui->connect_bt->setEnabled(false);

    ui->send_message->setEnabled(true);
    ui->disconnect_bt->setEnabled(true);
}

void MainWindow::ReadData()
{
    //获取服务器端发送过来的内容
    auto data = tcpsocket->readAll();

    if (ui->display_message->document()->blockCount() > 100){
        ui->display_message->clear();
    }
    ui->display_message->append("服务器端说："+data);
}

void MainWindow::disConnect()
{
    tcpsocket->disconnectFromHost();
    tcpsocket->close();
    tcpsocket=NULL;

    if (ui->display_message->document()->blockCount() > 100){
        ui->display_message->clear();
    }
    ui->display_message->append("客户端与服务器端断开成功！");

    ui->connect_bt->setEnabled(true);
}

void MainWindow::on_send_message_clicked()
{
    //获取文本框的输入，开始发送消息
    QString str=ui->text_input->text().trimmed();

    if(str.isEmpty()){
        ui->statusbar->showMessage("不能发送空消息哦！");
    }else {
        tcpsocket->write(str.toUtf8().data());
        ui->display_message->append("我跟服务器端说："+str);
    }
}

6、main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

7. Execution results

(1) The interface is as follows

(2) Connect to the tcp server

reference:

(1) Qt6 Tutorial III (13) TCP/IP Communication and Socket Programming

QT study notes: Implementation of TCP client

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