Qt多线程TCP服务器实现指南

在Qt中实现多线程TCP服务器可以通过为每个客户端连接分配独立的线程来处理，以提高并发性能。以下是一个分步实现的示例：

1. 自定义工作线程类（处理客户端通信）

// workerthread.h
#include <QObject>
#include <QTcpSocket>
#include <QThread>

class WorkerThread : public QObject
{
Q_OBJECT
public:
explicit WorkerThread(qintptr socketDescriptor, QObject *parent = nullptr);

public slots:
void processConnection();

signals:
void dataReceived(const QByteArray &data);
void finished();

private:
qintptr m_socketDescriptor;
QTcpSocket *m_socket;
};

// workerthread.cpp
WorkerThread::WorkerThread(qintptr socketDescriptor, QObject *parent)
: QObject(parent), m_socketDescriptor(socketDescriptor)
{
}

void WorkerThread::processConnection()
{
m_socket = new QTcpSocket();
if (!m_socket->setSocketDescriptor(m_socketDescriptor)) {
emit error(m_socket->error());
delete m_socket;
return;
}

connect(m_socket, &QTcpSocket::readyRead, [this]() {
QByteArray data = m_socket->readAll();
emit dataReceived(data);
// 回显数据示例
m_socket->write("Server received: " + data);
});

connect(m_socket, &QTcpSocket::disconnected, [this]() {
m_socket->deleteLater();
emit finished();
});
}

2. TCP服务器实现（主线程）

// tcpserver.h
#include <QTcpServer>
#include <QList>

class TcpServer : public QTcpServer
{
Q_OBJECT
public:
explicit TcpServer(QObject *parent = nullptr);
void startServer(quint16 port);

protected:
void incomingConnection(qintptr socketDescriptor) override;

private:
QList<QThread*> m_threads;
};

// tcpserver.cpp
TcpServer::TcpServer(QObject *parent) : QTcpServer(parent) {}

void TcpServer::startServer(quint16 port)
{
if (!listen(QHostAddress::Any, port)) {
qDebug() << "Server could not start!";
} else {
qDebug() << "Server started on port" << port;
}
}

void TcpServer::incomingConnection(qintptr socketDescriptor)
{
QThread *thread = new QThread();
WorkerThread *worker = new WorkerThread(socketDescriptor);
worker->moveToThread(thread);

connect(thread, &QThread::started, worker, &WorkerThread::processConnection);
connect(worker, &WorkerThread::finished, thread, &QThread::quit);
connect(worker, &WorkerThread::finished, worker, &WorkerThread::deleteLater);
connect(thread, &QThread::finished, thread, &QThread::deleteLater);

thread->start();
m_threads.append(thread);
}

3. 使用服务器（主函数）

#include "tcpserver.h"

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);

TcpServer server;
server.startServer(1234);

return a.exec();
}

关键点说明：

高级优化建议：

class ConnectionTask : public QRunnable {
public:
ConnectionTask(qintptr descriptor) : m_descriptor(descriptor) {}

void run() override {
QTcpSocket socket;
socket.setSocketDescriptor(m_descriptor);
// 处理通信逻辑
}
private:
qintptr m_descriptor;
};

// 在incomingConnection中：
QThreadPool::globalInstance()->start(new ConnectionTask(socketDescriptor));

这种实现方式能够有效处理中等规模的并发连接（约数千连接），对于更高性能需求可以考虑：

• 使用epoll/kqueue等IO多路复用技术
• 结合异步IO（QAbstractSocket::waitFor…系列函数要谨慎使用）
• 采用Reactor模式或Proactor模式