QT学习_网络编程_TCP通信聊天

Posted 2021-11-10 Leslie X徐

网络编程

TCP通信

1.用到的类

• QTcpServer

公共函数：

void 				close ()
QString 		errorString () const
bool 				isListening () const
bool 				listen ( const QHostAddress & address = QHostAddress::Any, quint16 port = 0 )
QHostAddress 	serverAddress () const
quint16 		serverPort () const
bool 				waitForNewConnection ( int msec = 0, bool * timedOut = 0 )

virtual QTcpSocket * 	nextPendingConnection ()

信号：
void 		newConnection()

version5：
void 		acceptError(QAbstractSocket::SocketError socketError)



保护函数：

void 				addPendingConnection ( QTcpSocket * socket )
virtual void 	incomingConnection ( int socketDescriptor )

• QAbstractSocket

参数：

enum NetworkLayerProtocol { IPv4Protocol, IPv6Protocol, UnknownNetworkLayerProtocol }
enum SocketError { ConnectionRefusedError, RemoteHostClosedError, HostNotFoundError, SocketAccessError, ..., UnknownSocketError }
enum SocketOption { LowDelayOption, KeepAliveOption, MulticastTtlOption, MulticastLoopbackOption }
enum SocketState { UnconnectedState, HostLookupState, ConnectingState, ConnectedState, ..., ListeningState }
enum SocketType { TcpSocket, UdpSocket, UnknownSocketType }


公共函数：

QAbstractSocket ( SocketType socketType, QObject * parent )

void 		abort ()
void 		connectToHost ( const QString & hostName, quint16 port, OpenMode openMode = ReadWrite )
void 		connectToHost ( const QHostAddress & address, quint16 port, OpenMode openMode = ReadWrite )
void 		disconnectFromHost ()

bool 		waitForConnected ( int msecs = 30000 )
bool 		waitForDisconnected ( int msecs = 30000 )

QHostAddress 	localAddress () const
quint16 			localPort () const
QHostAddress 	peerAddress () const
QString 			peerName () const
quint16 			peerPort () const

虚函数：
virtual qint64 	bytesAvailable () const
virtual qint64 	bytesToWrite () const
virtual bool 		canReadLine () const


信号：

void 		connected ()
void 		disconnected ()
void 		error ( QAbstractSocket::SocketError socketError )
void 		hostFound ()
void 		stateChanged ( QAbstractSocket::SocketState socketState )

继承的QIODevice信号：
void readyRead()

界面

服务器端

1.主窗口定义和构造函数
MainWindow.h:
定义私有变量tcpServer建立TCP服务器，定义tcpSocket用于与客户端进行socket连接和通信。

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLabel>
#include <QTcpServer>
#include <QTcpSocket>
#include <QHostInfo>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
private:
    QLabel *LabListen;
    QLabel *LabSocketState;
    QTcpServer *tcpServer;
    QTcpSocket *tcpSocket;
    QString getLocalIP();

protected:
    void closeEvent(QCloseEvent *event);
public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
private slots:
    void onNewConnection();//对应QTcpServer的newConnect信号
    void onSocketStateChange(QAbstractSocket::SocketState socketState);
    void onClientConnected();
    void onClientDisconnected();
    void onSocketReadyRead();//读取socket传入的数据

    void on_actStart_triggered();
    void on_actStop_triggered();
    void on_actClear_triggered();
    void on_actExit_triggered();
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

构造函数：

QString MainWindow::getLocalIP()
{
    QString hostName = QHostInfo::localHostName();//得到本地主机名
    QHostInfo hostInfo = QHostInfo::fromName(hostName);//根据主机名获得信息
    QString localIP = "";
    QList<QHostAddress> addList = hostInfo.addresses();//获得信息中的IP地址序列

    if(!addList.isEmpty())
    for (int i=0;i<addList.count();++i) {
            QHostAddress aHost = addList.at(i);
            if(QAbstractSocket::IPv4Protocol == aHost.protocol())
            {
                localIP = aHost.toString();
                break;
            }
     }
    return localIP;
}

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

    //状态栏设置
    LabListen = new QLabel("listen state: ");
    LabListen->setMinimumWidth(150);
    ui->statusBar->addWidget(LabListen);

    LabSocketState = new QLabel("socket state: ");
    LabSocketState->setMinimumWidth(200);
    ui->statusBar->addWidget(LabSocketState);

    //标题栏设置
    QString localIP = getLocalIP();
    this->setWindowTitle(this->windowTitle() + "----localIP: " + localIP);
    ui->comboBox->addItem(localIP);
    tcpServer = new QTcpServer(this);
    connect(tcpServer,SIGNAL(newConnection()),
            this,SLOT(onNewConnection()));
}

2.网络监听与socket建立
监听开始和停止：

void MainWindow::on_actStart_triggered()
{
    //start listening
    QString IP = ui->comboBox->currentText();
    qint16 port = ui->spinBox->value();
    QHostAddress addr(IP);

    tcpServer->listen(addr,port);//监听指定地址和端口
    //tcpServer->listen(QHostAddress::Any,port);

    ui->plainTextEdit->appendPlainText("**start listening...");
    ui->plainTextEdit->appendPlainText("**server Addr: " +
                                 tcpServer->serverAddress().toString());
    ui->plainTextEdit->appendPlainText("**server port: " +
                                 QString::number(tcpServer->serverPort()));
    ui->actStart->setEnabled(false);
    ui->actStop->setEnabled(true);
    LabListen->setText("listen state: listening");
}

void MainWindow::on_actStop_triggered()
{//停止监听
    if(tcpServer->isListening())
    {
        tcpServer->close();//停止监听
        ui->actStart->setEnabled(true);
        ui->actStop->setEnabled(false);
        LabListen->setText("Listing state: stop");
    }
}

socket建立与连接

void MainWindow::onNewConnection()
{
    tcpSocket = tcpServer->nextPendingConnection();

    connect(tcpSocket, SIGNAL(connected()),
            this, SLOT(onClientConnected()));
    
    connect(tcpSocket,SIGNAL(disconnected()),
            this, SLOT(onClientDisconnected()));
            
    connect(tcpSocket,SIGNAL(stateChanged(QAbstractSocket::SocketState)),
            this, SLOT(onSocketStateChange(QAbstractSocket::SocketState)));
    
    connect(tcpSocket,SIGNAL(readyRead()),
            this, SLOT(onSocketReadyRead()));
}

void MainWindow::onSocketStateChange(QAbstractSocket::SocketState socketState)
{//socket状态变化时
    switch (socketState) {
    case QAbstractSocket::UnconnectedState:
        LabSocketState->setText("socket state: UnconnectedState");
        break;
    case QAbstractSocket::HostLookupState:
        LabSocketState->setText("socket state: HostLookupState");
        break;
    case QAbstractSocket::ConnectingState:
        LabSocketState->setText("socket state: ConnectingState");
        break;
    case QAbstractSocket::BoundState:
        LabSocketState->setText("socket state: BoundState");
        break;
    case QAbstractSocket::ClosingState:
        LabSocketState->setText("socket state: ClosingState");
        break;
    case QAbstractSocket::ListeningState:
        LabSocketState->setText("socket state: ListeningState");
        break;
    case QAbstractSocket::ConnectedState:
        LabSocketState->setText("socket state: ConnectedState");
        break;
    }
}

void MainWindow::onClientConnected()
{//客户接入时
    ui->plainTextEdit->appendPlainText("**client socket connected");
    ui->plainTextEdit->appendPlainText("**peer address: " +
                                       tcpSocket->peerAddress().toString());
    ui->plainTextEdit->appendPlainText("**peer port: " +
                                       QString::number(tcpSocket->peerPort()));
}

void MainWindow::onClientDisconnected()
{//客户断开连接时
    ui->plainTextEdit->appendPlainText("**client socket disconnected");
    tcpSocket->deleteLater();
}

3.与客户端通信

//读取
void MainWindow::onSocketReadyRead()
{//数据通信
    //读取缓冲区行文本
    //canReadLine判断是否有新的一行数据需要读取
    //再用readLine函数读取一行数据
    while(tcpSocket->canReadLine())
        ui->plainTextEdit->appendPlainText("[receive] " +
                                           tcpSocket->readLine());
}

//发送
void MainWindow::on_pushButton_clicked()
{//发送一行字符串，以换行符结束
    QString msg = ui->lineEdit->text();
    ui->plainTextEdit->appendPlainText("[send] "+msg);
    ui->lineEdit->clear();
    ui->lineEdit->setFocus();//让键盘继续在lineedit框内

    QByteArray str = msg.toUtf8();
    str.append('\\n');
    tcpSocket->write(str);
}

客户端

1.主窗口定义和构造函数
主窗口定义：
客户端只使用一个QTcpSocket对象

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QTcpSocket>
#include <QLabel>
#include <QHostInfo>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT
private:
    QTcpSocket *tcpClient;
    QLabel *LabSocketState;
    QString getLocalIP();
protected:
    void closeEvent(QCloseEvent *event);
public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
private slots:
    void onConnected();
    void onDisconnected();
    void onSocketStateChange(QAbstractSocket::SocketState socketState);
    void onSocketReadyRead();
    
    void on_actLink_triggered();
    void on_actunLink_triggered();
    void on_pushButton_clicked();
    void on_actQuit_triggered();
    void on_actClear_triggered();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

构造函数：
主要功能：创建tcpClient，并建立信号与槽函数的关联

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

    //设置套接字
    tcpClient = new QTcpSocket(this);

    //设置状态栏
    LabSocketState = new QLabel("socket state:");
    LabSocketState->setMinimumWidth(250);
    ui->statusBar->addWidget(LabSocketState);
    //获得本机地址，设置标题栏
    QString localIP = getLocalIP();
    this->setWindowTitle(this->windowTitle()+
                         "localIP: "+localIP);
    ui->comboBox->addItem(localIP);

    //链接信号
    connect(tcpClient, SIGNAL(connected()),
            this, SLOT(onConnected()));
    connect(tcpClient, SIGNAL(disconnected()),
            this, SLOT(onDisconnected()));
    connect(tcpClient, SIGNAL(stateChanged(QAbstractSocket::SocketState)),
            this, SLOT(onSocketStateChange(QAbstractSocket::SocketState)));
    connect(tcpClient, SIGNAL(readyRead()),
            this, SLOT(onSocketReadyRead()));
}

2.建立连接
建立连接按钮：

void MainWindow::on_actLink_triggered()
{//连接到服务器
    QString addr = ui->comboBox->currentText();
    quint16 port = ui->spinBox->value();
    tcpClient->connectToHost(addr,port);
}

void MainWindow::on_actunLink_triggered()
{//断开连接
    if(tcpClient->state()==QAbstractSocket::ConnectedState)
        tcpClient->disconnectFromHost();
}

接受连接信号的槽函数：

void MainWindow::onConnected()
{
    ui->plainTextEdit->appendPlainText("**server connected...");
    ui->plainTextEdit->appendPlainText("**peer Addr: " +
                                 tcpClient->peerAddress().toString());
    ui->plainTextEdit->appendPlainText("**peer port: " +
                                 QString::number(tcpClient->peerPort()));
    ui->actLink->setEnabled(false);
    ui->actunLink->setEnabled(true);
}

void MainWindow::onDisconnected()
{
    ui->plainTextEdit->appendPlainText("**server disconnected");
    ui->actLink->setEnabled(true);
    ui->actunLink->setEnabled(false);
}

3.与服务器数据收发
采用基于行的数据通信协议

void MainWindow::on_pushButton_clicked()
{
    QString msg = ui->lineEdit->text();
    ui->plainTextEdit->appendPlainText("[send] "+msg);
    ui->lineEdit->clear();
    ui->lineEdit->setFocus();//让键盘继续在lineedit框内

    QByteArray str = msg.toUtf8();
    str.append('\\n');
    tcpClient->write(str);
}

void MainWindow::onSocketReadyRead()
{
    while(tcpClient->canReadLine())
            ui->plainTextEdit->appendPlainText("[receive] " +
                                               tcpClient->readLine());
}

代码总结

服务器和客户端的MainWindow.cpp代码
1.TCP_Server代码

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

QString MainWindow::getLocalIP()
{
    QString hostName = QHostInfo::localHostName();//得到本地主机名
    QHostInfo hostInfo = QHostInfo::fromName(hostName);//根据主机名获得信息
    QString localIP = "";
    QList<QHostAddress> addList = hostInfo.addresses();//获得信息中的IP地址序列

    if(!addList.isEmptyQT创建TCP Socket通信

 Linux网络编程——TCP和UDP通信
 Linux网络学习_网络的基本概念
 QT网络编程Tcp下C/S架构的即时通信
 阶段1 语言基础+高级_1-3-Java语言高级_07-网络编程_第2节 TCP协议_3_TCP通信的客户端代码实现
 开源应用QT—TCP网络上位机的设计