qt tcp服务端保证单个连接

在Qt中，如果你想要创建一个TCP服务端并确保每个客户端连接只处理一次，你可以利用Qt的`QAbstractSocket`类，特别是`QTcpServer`类。下面是一个基本的示例：

#include <QObject>
#include <QTcpServer>

class MyServer : public QObject {
    Q_OBJECT
public slots:
    void startListening() {
        TcpServer = new QTcpServer(this);
        if (!TcpServer->listen(QHostAddress::Any, 8000)) {
            qCritical("Failed to listen on port %d", 8000);
            return;
        }
        connect(TcpServer, &QTcpServer::newConnection, this, &MyServer::handleNewConnection);
    }

private slots:
    void handleNewConnection() {
        QTcpSocket *socket = TcpServer->nextPendingConnection();
        if (socket) {
            // 这里创建一个新的线程来处理新连接，避免阻塞主线程
            QThread *thread = new QThread(this);
            ClientHandler *handler = new ClientHandler(socket, thread);
            handler->moveToThread(thread);
            connect(handler, &ClientHandler::connectionClosed, thread, &QThread::quit);
            connect(thread, &QThread::started, handler, &ClientHandler::processData);
            connect(handler, &ClientHandler::finished, thread, &QThread::deleteLater);
            connect(thread, &QThread::finished, socket, &QTcpSocket::deleteLater);
            thread->start(); // 启动新线程处理连接
        } else {
            qDebug("No pending connections");
        }
    }

signals:
    void connectionClosed();

private:
    QTcpServer *TcpServer;
};

// 客户端处理类
class ClientHandler : public QObject {
    Q_OBJECT
public:
    explicit ClientHandler(QTcpSocket *socket, QThread *thread) : socket(socket), thread(thread) {}
    ~ClientHandler() { emit finished(); }

private slots:
    void processData() {
        // 在这里处理客户端的数据请求...
        emit connectionClosed(); // 当处理完毕后，关闭连接
    }

private:
    QTcpSocket *socket;
    QThread *thread;
};

在这个例子中，当有新的连接到来时，`handleNewConnection`会被调用，然后创建一个新的`ClientHandler`实例并放入单独的线程中处理。这样做可以防止服务器因为并发连接而阻塞。一旦处理完成，客户端会接收到`connectionClosed`信号，并自动关闭连接。