Qt：实现TCP同步与异步读写消息

一、异步读写

在 Qt 中实现 TCP 客户端和服务器的同步和异步读写消息涉及使用 QTcpSocket 和 QTcpServer 类。这两个类提供了用于建立 TCP 连接、发送和接收数据的功能。下面是一个简单的示例，演示了如何在 Qt 中实现 TCP 客户端和服务器的同步和异步读写消息：

TCP 服务器端示例（异步）

#include <QCoreApplication>
#include <QTcpServer>
#include <QTcpSocket>
#include <QDebug>int main(int argc, char *argv[])
{QCoreApplication a(argc, argv);QTcpServer server;server.listen(QHostAddress::Any, 1234); // 监听端口 1234QObject::connect(&server, &QTcpServer::newConnection, [&](){QTcpSocket* clientSocket = server.nextPendingConnection();QObject::connect(clientSocket, &QTcpSocket::readyRead, [&](){QByteArray requestData = clientSocket->readAll();qDebug() << "Received request from client:" << requestData;// Echo back the received dataclientSocket->write(requestData);});});qDebug() << "TCP server started. Listening on port 1234...";return a.exec();
}

TCP 客户端端示例（异步）

#include <QCoreApplication>
#include <QTcpSocket>
#include <QDebug>int main(int argc, char *argv[])
{QCoreApplication a(argc, argv);QTcpSocket client;client.connectToHost("127.0.0.1", 1234); // 连接到服务器的 IP 地址和端口QObject::connect(&client, &QTcpSocket::connected, [&](){qDebug() << "Connected to server.";// Send a message to the serverclient.write("Hello, Server!");});QObject::connect(&client, &QTcpSocket::readyRead, [&](){QByteArray responseData = client.readAll();qDebug() << "Received response from server:" << responseData;});return a.exec();
}

示例简单演示了如何在 Qt 中实现 TCP 客户端和服务器的异步读写消息。在异步通信中，使用信号和槽机制来处理数据的接收和发送。

二、同步读写

以下是一个简单的示例，演示了如何在 Qt 中实现 TCP 客户端和服务器的同步读写消息：

TCP 服务器端示例（同步）

#include <QCoreApplication>
#include <QTcpServer>
#include <QTcpSocket>
#include <QDebug>int main(int argc, char *argv[])
{QCoreApplication a(argc, argv);QTcpServer server;server.listen(QHostAddress::Any, 1234); // 监听端口 1234if (!server.isListening()) {qDebug() << "Failed to start TCP server.";return 1;}QTcpSocket* clientSocket = nullptr;while (true) {if (server.hasPendingConnections()) {clientSocket = server.nextPendingConnection();break;}}if (clientSocket) {qDebug() << "Client connected.";// Read data from clientQByteArray requestData = clientSocket->readAll();qDebug() << "Received request from client:" << requestData;// Echo back the received dataclientSocket->write(requestData);}return a.exec();
}

TCP 客户端端示例（同步）

#include <QCoreApplication>
#include <QTcpSocket>
#include <QDebug>int main(int argc, char *argv[])
{QCoreApplication a(argc, argv);QTcpSocket client;client.connectToHost("127.0.0.1", 1234); // 连接到服务器的 IP 地址和端口if (!client.waitForConnected()) {qDebug() << "Failed to connect to server.";return 1;}qDebug() << "Connected to server.";// Send a message to the serverclient.write("Hello, Server!");if (!client.waitForBytesWritten()) {qDebug() << "Failed to write data to server.";return 1;}if (!client.waitForReadyRead()) {qDebug() << "Failed to read response from server.";return 1;}// Read response from serverQByteArray responseData = client.readAll();qDebug() << "Received response from server:" << responseData;return a.exec();
}

示例简单演示了如何在 Qt 中实现 TCP 客户端和服务器的同步读写消息。在同步通信中，使用 waitForConnected、waitForBytesWritten 和 waitForReadyRead 等方法来等待连接建立、数据写入和数据读取完成。这种方式适用于需要确保数据传输完整性和顺序性的场景。