c++ - QTcpSocket 为什么接收到错误的数据？

Question

我正在编写一个简单的网络应用程序。客户端发送到服务器消息服务器在 QTextEdit 中打印它并响应客户端。我正在使用 QTcpServer 和 QTcpSocket。有一个问题我无法解决。接收数据是 quint16 + QTime + QString，它作为 QByteArrey 发送。我使用 quint16 来接收数据 block 的大小。由于某种原因，当客户端发送到服务器时

next block size: 16 (quint16 value)
block size: 18 

服务器获取:

next block size: 30073  (quint16 value)
block size: 18 

如您所见，出于某种原因，服务器从 QDataStrem 获取了错误的变量值，它始终为 30073。我不明白为什么？

void Widget::slotSendToServer()
{
    logTextEdit->append("slotSendToServer()");
    QByteArray arrBlock;
    QDataStream serverSendStream(&arrBlock, QIODevice::ReadWrite);
    QString messageStr = messageLineEdit->text();

    serverSendStream << quint16(0) << QTime::currentTime()
                     << messageStr;

    serverSendStream.device()->seek(0);
    serverSendStream << (quint16)(arrBlock.size() - sizeof(quint16));

    qDebug() << "next_block_size:"
             <<(quint16)(arrBlock.size() - sizeof(quint16)) 
             << endl
             << "full size of Byte arrey:" << arrBlock.size();

    tcpSocket->write(arrBlock);
    messageLineEdit->clear();
}



void Widget::slotReadClient()
{
    logTextEdit->append("slotReadClient()");
    QTcpSocket *tcpSocket = (QTcpSocket*)sender();
    QDataStream clientReadStream(tcpSocket);

    while(true)
    {
        if (!next_block_size)
        {
            if (tcpSocket->bytesAvailable() < sizeof(quint16))
            {
                break;
            }
            clientReadStream >> next_block_size;
        }

        if (tcpSocket->bytesAvailable() < next_block_size)
        {
            break;
        }
        QTime   time;
        QString messageTextStr;
        clientReadStream >> time >> messageTextStr;

        QString messageCompleteStr =
                time.toString() + " " + "Client has sent - " 
                                + messageTextStr;
        logTextEdit->append("Message received: ");
        logTextEdit->append(messageCompleteStr);

        next_block_size = 0;

        sendToClient(tcpSocket,
                     "Server Response: Received \"" 
                      + messageTextStr + "\"");
    }
}

Answer 1

您应该确保每次套接字连接时变量 next_block_size 都被初始化为 0。

如果您不重用相同的QTcpSocket 对象，这可以在您的Widget 类构造函数中完成，或者如果您这样做，在连接到信号的插槽中完成连接()。