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 serverbytesToWrite = TotalBytes - int(tcpClient.write(QByteArray(PayloadSize, '@')));clientStatusLabel->setText(tr("Connected"));
}
void Dialog::updateClientProgress(qint64 numBytes)
{// called when the TCP client has written some bytesbytesWritten += 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_CURSORQApplication::restoreOverrideCursor();
#endif}
}
关于更多
- 在QtCreator软件可以找到：
- 或在以下Qt安装目录找到：
C:Qt{你的Qt版本}Examples{你的Qt版本}networkloopback- 相关链接
https://doc.qt.io/qt-5/qtnetwork-loopback-example.html- Qt君公众号回复『Qt示例』获取更多内容。
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