聊天室代码：

#include "cli.h"
#include "ui_cli.h"

Cli::Cli(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Cli)
{
    ui->setupUi(this);
    socket = new QTcpSocket(this);
    connect(socket,&QTcpSocket::connected,this,&Cli::connect_slot);
    //客户端与服务器连接成功后，如果服务器向客户端发来数据，客户端就会自动发送一个readyRead信号
    connect(socket,&QTcpSocket::readyRead,this,&Cli::readyRead_slot);
    connect(socket,&QTcpSocket::disconnected,this,&Cli::disconnect_slot);
}

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

//连接服务器按钮对应的槽
void Cli::on_ConnectBtn_clicked()
{
    //获取UI界面的信息
    userName=ui->UserEdit->text();
    QString hostName = ui->IPEdit->text();
    quint16 port = ui->PortEdit->text().toUInt();
    qDebug() << "Connecting to host: " << hostName << " Port: " << port;
    //调用连接函数到主机
    //参数1：要连接的服务器主机地址
    //参数2：端口号
    //返回值：无
    socket->connectToHost(hostName,port);
    //如果连接服务器成功，该客户端回发送一个connected的信号
    //可以将信号连接到自定义的槽函数中处理相关逻辑
    //只连接一次 所有可以写在构造函数中
}

void Cli::connect_slot()
{
    QMessageBox::information(this,"成功","连接服务器成功");
    QString msg = userName + ":进入聊天室";
    socket->write(msg.toLocal8Bit());
}

void Cli::readyRead_slot()
{
    QByteArray msg = socket->readAll();
    //将数据展示在UI界面
    ui->MsgList->addItem(QString::fromLocal8Bit(msg));
}

void Cli::on_SendBtn_clicked()
{
    QString m =ui->MsgEdit->text();
    QString msg = userName+":"+m;
    socket->write(msg.toLocal8Bit());
    ui->MsgEdit->clear();
}

void Cli::on_DisBtn_clicked()
{
    QString msg=userName+":离开聊天室";
    socket->disconnectFromHost();
    //断开连接后 会向服务器发送disconnected信号
}

void Cli::disconnect_slot()
{
    QMessageBox::information(this,"断开成功","断开成功");
}