QT TCP/IP网络通信

TCP/IP通信（即SOCKET通信）是通过网线将服务器Server端和客户机Client端进行连接，在遵循ISO/OSI模型的四层层级构架的基础上通过TCP/IP协议建立的通讯。

以下代码为模拟客户端网络通信，所使用到服务端模拟器（TCP&UDP测试工具）

要实现网络通信，需要用到QTcpServer（监听套接字）和QTcpSocket（通讯套接字），首先在pro文件中添加network模块。

client.pro

#-------------------------------------------------
#
# Project created by QtCreator 2022-08-26T10:44:00
#
#-------------------------------------------------

QT       += core gui network

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = Client
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0


SOURCES += \
        main.cpp \
        widget.cpp

HEADERS += \
        widget.h

FORMS += \
        widget.ui

main.cpp

#include "widget.h"
#include 

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include 
#include        //qt中的tcp套接字头文件
#include 
#include 
#include 
namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private slots:
    void on_btnStart_clicked();

    void netConnected();
    void netDisConnected();
    void netError(QAbstractSocket::SocketError sError);
    void recvData();
    void on_btnSend_clicked();
    void on_btnClrSend_clicked();
    void on_btnClrRecv_clicked();
    void on_btnClrBytes_clicked();
private:
    Ui::Widget *ui;
    QTcpSocket *socket;
    int sendLen = 0;
    int recvLen= 0;
};

#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#pragma execution_character_set("utf-8")
Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->btnSend->setDisabled(true);
    setWindowTitle("客户端");
}

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

void Widget::on_btnStart_clicked()
{
    static bool flag = true;
    if(flag){
        ui->btnStart->setText("正在连接....");

        QString ip = ui->edtip->text();
        int port = ui->edtport->text().toInt();
        if(ip.isEmpty() || ui->edtport->text().isEmpty()){
            return;
        }
        //构造套接字
        socket =new QTcpSocket(this);
        //关联网络连接成功的信号
        connect(socket,&QTcpSocket::connected,this,&Widget::netConnected);
        //关联网络断开连接成功的信号
        connect(socket,&QTcpSocket::disconnected,this,&Widget::netDisConnected);
        //关联网络错误的信号
        connect(socket,QOverload::of(&QAbstractSocket::error),
                this,&Widget::netError);
        //关联读缓存有数据的信号，当读缓存区有一个字节的数据，
        //就立即触发该信号，此时，就调用该槽函数read读数据
        connect(socket,&QTcpSocket::readyRead,this,&Widget::recvData);
        //连接到服务器
        socket->connectToHost(ip,port);
        flag = false;
    }
    else{
        flag = true;
        socket->disconnectFromHost();
        socket->close();
    }
}
void Widget::netConnected()
{
    ui->btnStart->setText("断开连接");
    ui->btnSend->setDisabled(false);
    //断开信号与槽的连接
    disconnect(socket,&QTcpSocket::connected,this,&Widget::netConnected);
}
void Widget::netDisConnected()
{
    ui->btnStart->setText("连接");
    ui->btnSend->setDisabled(true);
    //断开信号与槽的连接，避免占用信号与槽的队列，提高程序的健壮性
    disconnect(socket,&QTcpSocket::disconnected,this,&Widget::netDisConnected);
    disconnect(socket, QOverload::of(&QAbstractSocket::error),
    this, &Widget::netError);
    disconnect(socket,&QTcpSocket::readyRead,this,&Widget::recvData);

}
void Widget::netError(QAbstractSocket::SocketError sError)
{
    QString error;
    qDebug() << sError;
    switch (sError) {
    case QAbstractSocket::ConnectionRefusedError:
        error = "ConnectionRefuseError";
        break;
    case QAbstractSocket::HostNotFoundError:
        error = "HostNotFoundError";

    default:
        break;
    }
    QMessageBox::critical(this,"错误",error);
}
void Widget::on_btnSend_clicked()
{
    QString buf = ui->tdtSend->toPlainText();
    sendLen += socket->write(buf.toLatin1());
    //number()：将int 转换为QString类型
    ui->edtSend->setText(QString::number(sendLen));
}

void Widget::on_btnClrSend_clicked()
{
    ui->tdtSend->clear();
}

void Widget::on_btnClrRecv_clicked()
{
    ui->tdtRecv->clear();
}

void Widget::on_btnClrBytes_clicked()
{
    sendLen = 0;
    ui->edtSend->setText( QString::number(sendLen) );
    recvLen = 0;
    ui->edtRecv->setText( QString::number(recvLen) );
}


void Widget::recvData()
{
    //bytesAvailable()：返回读缓存中的有效字节数
    qDebug() <<"bytes: "<< socket->bytesAvailable();
    //readAll()：读取缓冲区所有可用的数据，用于少量数据传输
//    QByteArray buf = socket->readAll();
    //read(int)：从读缓存区中读取32个字节的数据，常用与大量数据传输，结合bytesAvailable()使用
    QByteArray buf = socket->read(32);
    if(buf.isEmpty()){
        return ;
    }
    recvLen += buf.length();
    ui->edtRecv->setText(QString::number(recvLen));
    ui->tdtRecv->append(buf);
}

运行界面