10.4QT实现TCP服务器客户端搭建的代码，现象

服务器：

.pro:

QT       += core gui network

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked 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 it uses 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

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

widget.h:

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTcpServer>       //服务器头文件
#include <QTcpSocket>       //客户端头文件
#include <QList>            //链表容器
#include <QMessageBox>      //消息对话框
#include <QDebug>           //测试

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

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

private slots:
    void on_startBtn_clicked();

    void newConnection_slot();
    void readyRead_slot();

private:
    Ui::Widget *ui;

    //定义服务器指针
    QTcpServer *server;
    //定义客户端容器
    QList<QTcpSocket *> clientList;
};
#endif // WIDGET_H

widget.cpp:

#include "widget.h"
#include "ui_widget.h"

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

    //实例化一个服务器
    server = new QTcpServer;

    connect(server, &QTcpServer::newConnection, this, &Widget::newConnection_slot);

}

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

//启动服务器按钮对应的槽函数
void Widget::on_startBtn_clicked()
{
    quint16 port = ui->portEdit->text().toUInt();       //获取ui界面上的端口号

    //监听客户端的连接请求
    if(!server->listen(QHostAddress::Any, port)){
        QMessageBox::critical(this, "失败", "监听失败");
        return;
    }else{
        QMessageBox::information(this, "成功", "服务器启动成功");
    }

    //此时，服务器已经成功进入监听状态，如果有客户端向服务器发来请求
    //那么该服务器，就会自动发射一个newconnection信号，我们可以将该信号连接到对应槽函数中执行相关逻辑
    //由于只需要进行一次连接即可，所以可以将该连接放在构造函数中完成
}

//自定义处理newConnection信号的槽函数的定义
void Widget::newConnection_slot()
{
    qDebug()<<"您有新的客户端发来请求";

    //获取最新连接的客户端套接字
    QTcpSocket* s = server->nextPendingConnection();
    //将该套接字放入客户端链表中
    clientList.push_back(s);

    //至此，多个客户端已经和服务器建立连接，并放入客户端容器中了
    //此时，如果有客户端向服务器发来数据，那么对应的客户端套接字就会自动发射一个readyRead信号
    //我们可以将该信号连接到自定义的槽函数中，处理相关逻辑
    connect(s, &QTcpSocket::readyRead, this, &Widget::readyRead_slot);
}

//自定义处理readyRead信号的槽函数的声明
void Widget::readyRead_slot()
{
    qDebug()<<"您有新的客户端消息发来";

    //遍历客户端链表，将无效的客户端移除
    for(int i=0; i<clientList.size(); i++){
        //判断当前套接字是否是有效连接
        if(0 == clientList[i]->state()){
            //如果是0，表示该套接字为无效连接，将该套接字移除出客户端容器
            clientList.removeAt(i);
            i--;
        }
    }

    //遍历客户端链表，判断是哪个客户端发来的数据
    for(int i=0; i<clientList.size(); i++){
        //获取当前套接字中待读数据的字节数，0说明无数据待读
        if(clientList[i]->bytesAvailable()){
            //将该套接字中的数据读取出来
            QByteArray msg = clientList[i]->readAll();

            //将数据展示到ui界面
            ui->msgWidget->addItem(QString::fromLocal8Bit(msg));

            //将接收到的数据转发给所有客户端
            for (int j=0; j<clientList.size(); j++) {
                clientList[j]->write(msg);
            }
        }
    }
}

widget.ui:

客户端：

.pro:

QT       += core gui network

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked 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 it uses 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

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

widget.h:

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTcpSocket>   //客户端类
#include <QMessageBox>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

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

private slots:
    void on_connectBtn_clicked();

    void connected_slot();
    void readyRead_slot();

    void on_sendBtn_clicked();

    void on_disconnectBtn_clicked();

    void disconnected_slot();

private:
    Ui::Widget *ui;

    //定义客户端指针
    QTcpSocket *socket;

    //定义字符串接收用户名
    QString usrname;
};
#endif // WIDGET_H

widget.cpp:

#include "widget.h"
#include "ui_widget.h"

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

    //给客户端指针实例化对象
    socket = new QTcpSocket(this);

    connect(socket, &QTcpSocket::connected, this, &Widget::connected_slot);

    //如果服务器向客户端发来消息，那么该客户端会自动发射一个readyRead信号，我们可以将信号连接到自定义槽函数中处理
    connect(socket, &QTcpSocket::readyRead, this, &Widget::readyRead_slot);

    connect(socket, &QTcpSocket::disconnected, this, &Widget::disconnected_slot);
}

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

//连接服务器按钮对应的槽函数
void Widget::on_connectBtn_clicked()
{
    //获取ui界面上的相关信息
    usrname = ui->usrnameEdit->text();  //获取用户名
    QString ip = ui->IPEdit->text();    //获取ip地址
    quint16 port = ui->portEdit->text().toUInt();    //获取端口号
    //将客户端连接到给定的服务器
    socket->connectToHost(ip, port);

    //此时，已经向服务器发送连接请求了，如果成功连接服务器，那么客户端会自动发送一个connected的信号
}

//自定义处理connected的信号的槽函数的定义
void Widget::connected_slot()
{
    QMessageBox::information(this, "成功", "您已经成功进入聊天室");
    //向服务器发送一条数据：xxx进入聊天室
    QString msg = usrname+": 进入聊天室";

    socket->write(msg.toLocal8Bit());       //将数据发送给服务器
}

//自定义处理readyRead信号的槽函数的定义
void Widget::readyRead_slot(){
    //读取套接字中的信息
    QByteArray msg = socket->readAll();

    //将数据展示到ui界面
    ui->msgWidget->addItem(QString::fromLocal8Bit(msg));
}

//发送按钮对应的槽函数
void Widget::on_sendBtn_clicked()
{
    //获取ui界面输入的内容
    QString msg = usrname + ":" + ui->msgEdit->text();

    //发送给服务器
    socket->write(msg.toLocal8Bit());

    //清空编辑框内容
    ui->msgEdit->clear();
}

//断开服务器按钮对应的槽函数
void Widget::on_disconnectBtn_clicked()
{
    //告诉大家我走了
    QString msg = usrname + ": 离开聊天室";
    socket->write(msg.toLocal8Bit());

    //断开连接
    socket->disconnectFromHost();

    //当成功与服务器断开连接后，该客户端会自动发送一个disconnected的信号
    //可以连接到自定义槽函数处理
}

//自定义的处理disconnected信号的槽函数的定义
void Widget::disconnected_slot()
{
    QMessageBox::information(this, "提示", "退出成功");
}

widget.ui:

实现效果：