Using TCP server and client in Qt

Using TCP server and client in Qt

TCP (Transmission Control Protocol) is a reliable, highly optimized Internet communication protocol that is widely used in various network applications. In this blog, we will introduce how to use TCP server and client in Qt.

Create a TCP server using Qt

To create a TCP server using Qt, you need to complete the following steps:

Step 1: Create QTcpServer object

QTcpServer *server = new QTcpServer(this);

Step 2: Listen for connection requests

Before you start listening, you need to use the listen() method to specify the service port number and listen for connection requests from a specific IP address.

if (!server->listen(QHostAddress::Any, 12345))
{
    
    
    qDebug() << "Failed to start server";
    return;
}

Step 3: Handle new connection requests

Whenever a new connection request arrives at the server, QTcpServer will notify you by emitting the newConnection() signal. You can use the accept() method to accept the connection and create a new QTcpSocket object to send and receive messages.

void MyTcpServer::newConnection()
{
    
    
    QTcpSocket *socket = server->nextPendingConnection();
    connect(socket, SIGNAL(readyRead()), this, SLOT(readData()));
    connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
}

void MyTcpServer::readData()
{
    
    
    QTcpSocket *socket = static_cast<QTcpSocket *>(sender());
    QByteArray data = socket->readAll();
    // 处理接收到的数据
}

Step 4: Send data

Use QTcpSocket's write() method to send your data to the connected client.

socket->write("Hello world");

Create TCP client using Qt

To create a TCP client using Qt, you need to complete the following steps:

Step 1: Create QTcpSocket object

QTcpSocket *m_socket = new QTcpSocket(this);

Step 2: Connect to the server

Use the connectToHost() method to connect the socket to the target host and port. After the connection is successful, QTcpSocket will send the connected() signal.

m_socket->connectToHost(QHostAddress("127.0.0.1"), 12345);

Step 3: Send and receive data

Use the write() method to send data to the server and process the received data through the readyRead() signal.

void MyTcpClient::sendData(QString data)
{
    
    
    m_socket->write(data.toUtf8().constData());
}

void MyTcpClient::readData()
{
    
    
    QString data = m_socket->readAll();
    // 处理接收到的数据
}

Summarize

Using TCP servers and clients in Qt is a reliable and efficient method for network communication. The QTcpServer and QTcpSocket classes provide an object-oriented solution that allows you to easily develop various types of network applications.

However, be aware of delays and exceptions that can occur for a variety of reasons (such as network outages, remote hosts closing connections, etc.) and be sure to handle these situations in your code to ensure application stability.