Qt官方示例-TCP客户端/服务器示例-蒲公英云

Qt官方示例-TCP客户端/服务器示例

清疚 2023-06-23 14:26 182阅读 0赞

该示例演示了在本地主机上的TCP客户端和服务器是如何通讯的。

客户端

绑定信号槽。

connect(&tcpClient, &QAbstractSocket::connected, this, &Dialog::startTransfer); /* 连接到服务器时回送消息给服务器 */
connect(&tcpClient, &QIODevice::bytesWritten,
        this, &Dialog::updateClientProgress); /* 绑定写数据到服务器的信号槽 */

连接到服务器。

tcpClient.connectToHost(QHostAddress::LocalHost, tcpServer.serverPort());

这里比较有意思的是，客户端连接到服务器->客户端(tcpClient)触发startTransfer槽函数->调用tcpClient.write->触发QIODevice::bytesWritten信号->触发updateClientProgress槽函数调用->就一直tcpClient.write，直到if条件不成立后后停止发送。

void Dialog::startTransfer()
{ 
    // called when the TCP client connected to the loopback server
    bytesToWrite = TotalBytes - int(tcpClient.write(QByteArray(PayloadSize, '@')));
    clientStatusLabel->setText(tr("Connected"));
}
void Dialog::updateClientProgress(qint64 numBytes)
{ 
    // called when the TCP client has written some bytes
    bytesWritten += int(numBytes);
    // only write more if not finished and when the Qt write buffer is below a certain size.
    if (bytesToWrite > 0 && tcpClient.bytesToWrite() <= 4 * PayloadSize) /* 直到if条件不成立后后停止发送 */
        bytesToWrite -= tcpClient.write(QByteArray(qMin(bytesToWrite, PayloadSize), '@'));
    clientProgressBar->setMaximum(TotalBytes);
    clientProgressBar->setValue(bytesWritten);
    clientStatusLabel->setText(tr("Sent %1MB").arg(bytesWritten / (1024 * 1024)));
}

服务端

绑定信号槽用于新连接：

connect(&tcpServer, &QTcpServer::newConnection,
        this, &Dialog::acceptConnection);

监听客户端连接。

!tcpServer.isListening() && !tcpServer.listen()

服务端新连接到来：

void Dialog::acceptConnection()
{ 
    tcpServerConnection = tcpServer.nextPendingConnection();
    if (!tcpServerConnection) { 
        serverStatusLabel->setText(tr("Error: got invalid pending connection!"));
        return;
    }
    connect(tcpServerConnection, 
            &QIODevice::readyRead,
            this, 
            &Dialog::updateServerProgress); /* 接受客户端数据的槽函数 */
    connect(tcpServerConnection,
            QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error),
            this, 
            &Dialog::displayError); /* 错误反馈 */
    connect(tcpServerConnection, 
            &QTcpSocket::disconnected,
            tcpServerConnection, 
            &QTcpSocket::deleteLater); /* 断开反馈 */
    serverStatusLabel->setText(tr("Accepted connection"));
    tcpServer.close(); 
}

接收来自客户端的数据：

void Dialog::updateServerProgress()
{ 
    bytesReceived += int(tcpServerConnection->bytesAvailable());
    tcpServerConnection->readAll(); /* 读数据 */
    serverProgressBar->setMaximum(TotalBytes);
    serverProgressBar->setValue(bytesReceived); /* 设置进度条 */
    serverStatusLabel->setText(tr("Received %1MB") /* 显示在界面上 */
                               .arg(bytesReceived / (1024 * 1024)));
    if (bytesReceived == TotalBytes) { 
        tcpServerConnection->close();
        startButton->setEnabled(true);
#ifndef QT_NO_CURSOR
        QApplication::restoreOverrideCursor();
#endif
    }
}