QT TCP服务器实现

港控/mmm° 2022-11-12 04:24 190阅读 0赞

# 1.TCP通信概述 #

tcp是一种用于数据传输的低级网络协议，它是可靠的、面向流、面向连接的传输协议，特别适合于连续数据传输。

服务器端使用QTcpServer用于端口监听，建立服务器；QTcpSocket用于建立连接后使用套接字进行通信。

[TCP详解][TCP]

# 2.常用API #

void close() 关闭服务器，停止网络监听

bool listen() 在给定IP地址和端口上进行监听

QTcpSocket \*nextPendingConnection() 返回下一个等待接入的连接

bool waitForNewConnection() 以阻塞方式等待新连接

# 3.示例 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3d6ejk1MzIwMDQ2Mw_size_16_color_FFFFFF_t_70][]

服务器端程序首先使用listen()开始服务器监听，可以指定IP和端口，一般一个服务器程序只监听某个端口的网络连接。

当有新的客户端接入时，QTcpServer内部的incomingConnection()函数会创建一个与客户端连接的QTcpSocket对象，然后发射信号newConnection()。

所以在客户端与服务器建立TCP连接后，具体的数据通信是通过QTcpSocket完成的。

#ifndef WIDGET_H
    #define WIDGET_H
    
    #include <QWidget>
    #include <QTcpServer>
    #include <QTcpSocket>
    
    namespace Ui {
    class Widget;
    }
    
    class Widget : public QWidget
    {
        Q_OBJECT
    
    public:
        explicit Widget(QWidget *parent = 0);
        ~Widget();
    
    private slots:
    
        void on_btnStart_clicked();
    
        void on_btnStop_clicked();
    
        void on_btnClear_clicked();
    
        void on_newConnection();
    
        void onConnected();
    
        void onDisConnected();
    
        void onStateChanged(QAbstractSocket::SocketState socketState);
    
        void onReadyRead();
    
        void on_btnSend_clicked();
    
    private:
        Ui::Widget *ui;
    
        QTcpServer *m_tcpServer = nullptr;
        QTcpSocket *m_tcpSocket = nullptr;
    };
    
    #endif // WIDGET_H

#include "widget.h"
    #include "ui_widget.h"
    #include <QHostInfo>
    
    Widget::Widget(QWidget *parent) :
        QWidget(parent),
        ui(new Ui::Widget)
    {
        ui->setupUi(this);
    
        //本地主机名
        QString hostName = QHostInfo::localHostName();
    
        //本机IP地址
        QHostInfo hostInfo = QHostInfo::fromName(hostName);
    
        //IP地址列表
        QList<QHostAddress> addrList = hostInfo.addresses();
        for(int i=0;i<addrList.count();i++)
        {
            QHostAddress host = addrList.at(i);
    
            if(QAbstractSocket::IPv4Protocol == host.protocol())
            {
                QString ip = host.toString();
                ui->comboBox->addItem(ip);
            }
        }
    
        m_tcpServer = new QTcpServer(this);
        connect(m_tcpServer,&QTcpServer::newConnection,this,&Widget::on_newConnection);
    }
    
    Widget::~Widget()
    {
        delete ui;
    }
    
    void Widget::on_btnStart_clicked()
    {
        //当前选择的ip
        QString ip = ui->comboBox->currentText();
    
        //端口
        int port = ui->lineEditPort->text().toInt();
    
        QHostAddress addr(ip);
    
        //监听
        m_tcpServer->listen(addr,port);
    
        ui->plainTextEdit->appendPlainText("**开始监听...");
    
        ui->plainTextEdit->appendPlainText("**服务器地址: "+m_tcpServer->serverAddress().toString());
    
        ui->plainTextEdit->appendPlainText("**服务器端口: "+QString::number(m_tcpServer->serverPort()));
    
        ui->btnStart->setEnabled(false);
    
        ui->btnStop->setEnabled(true);
    
        ui->lbListen->setText("正在监听");
    }
    
    void Widget::on_btnStop_clicked()
    {
        if(m_tcpServer->isListening())
        {
            m_tcpServer->close();
            ui->btnStart->setEnabled(true);
            ui->btnStop->setEnabled(false);
            ui->lbListen->setText("停止监听");
            ui->plainTextEdit->appendPlainText("**停止监听**");
        }
    }
    
    void Widget::on_btnClear_clicked()
    {
        ui->plainTextEdit->clear();
    }
    
    void Widget::on_newConnection()
    {
        m_tcpSocket = m_tcpServer->nextPendingConnection();
        connect(m_tcpSocket,&QTcpSocket::connected,this,&Widget::onConnected);
        connect(m_tcpSocket,&QTcpSocket::disconnected,this,&Widget::onDisConnected);
        connect(m_tcpSocket,&QTcpSocket::stateChanged,this,&Widget::onStateChanged);
        connect(m_tcpSocket,&QTcpSocket::readyRead,this,&Widget::onReadyRead);
    
        ui->plainTextEdit->appendPlainText("** client socket connected");
        ui->plainTextEdit->appendPlainText("** peer address: "+m_tcpSocket->peerAddress().toString());
        ui->plainTextEdit->appendPlainText("** peer port: "+QString::number(m_tcpSocket->peerPort()));
    }
    
    void Widget::onConnected()
    {
        ui->plainTextEdit->appendPlainText("** client socket connected");
        ui->plainTextEdit->appendPlainText("** peer address: "+m_tcpSocket->peerAddress().toString());
        ui->plainTextEdit->appendPlainText("** peer port: "+QString::number(m_tcpSocket->peerPort()));
    }
    
    void Widget::onDisConnected()
    {
        ui->plainTextEdit->appendPlainText("** client socket disconnected");
        m_tcpSocket->deleteLater();
    }
    
    void Widget::onStateChanged(QAbstractSocket::SocketState socketState)
    {
        switch (socketState)
        {
        case QAbstractSocket::UnconnectedState:
            ui->lbListen->setText("UnconnectedState");break;
        case QAbstractSocket::HostLookupState:
            ui->lbListen->setText("HostLookupState");break;
        case QAbstractSocket::ConnectedState:
            ui->lbListen->setText("ConnectedState");break;
        case QAbstractSocket::ConnectingState:
            ui->lbListen->setText("ConnectingState");break;
        case QAbstractSocket::BoundState:
            ui->lbListen->setText("BoundState");break;
        case QAbstractSocket::ClosingState:
            ui->lbListen->setText("ClosingState");break;
        case QAbstractSocket::ListeningState:
            ui->lbListen->setText("ListeningState");break;
        }
    
    }
    
    void Widget::onReadyRead()
    {
        while(m_tcpSocket->canReadLine())
        {
            ui->plainTextEdit->appendPlainText("[in] "+m_tcpSocket->readLine());
        }
    }
    
    void Widget::on_btnSend_clicked()
    {
        QString msg =ui->lineEdit->text();
        ui->plainTextEdit->appendPlainText("[out]"+msg);
        QByteArray str = msg.toUtf8();
        str.append('\n');
        m_tcpSocket->write(str);
    }

**一般TCP服务器程序允许多个客户端接入，本例只演示了一个客户端接入，为了使每个socket连接通信互不影响，一般采用多线程，即为一个socket连接创建一个线程。**

# 4.与客户端通信 #

![20210322212905227.gif][]

# 5.客户端程序 #

[客户端程序][Link 1]

[TCP]: https://blog.csdn.net/wzz953200463/article/details/103355661
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3d6ejk1MzIwMDQ2Mw_size_16_color_FFFFFF_t_70]: /images/20221022/74a35ca0d98a4eb286e7fab4cbebb9a9.png
[20210322212905227.gif]: /images/20221022/a71fd4e3de0346cb9b7ba4f8566f4a81.png
[Link 1]: https://blog.csdn.net/wzz953200463/article/details/115100295