【关于QT5的问题】QTcpSocket 为什么一次只能读到8192个字节？

if (m_client->bytesAvailable() > 0)

{

	QByteArray buffer = m_client->read(MAX_BUFFER_SIZE));

        //这里的这个buffer总是8192，为什么？

}

int FileSender::sendFile(QString strFilePath, QString strFileName)

{

	//打开文件

	QFile file(strFilePath);

	if (file.open(QIODevice::ReadOnly) == false)

	{

		return -1;

	}



	//分配缓冲区

	struct file_head *head = (struct file_head*)malloc(MAX_BUFFER_SIZE);

	if (head == NULL)

	{

		return -1;

	}



	//获得缓冲区指针

	char *pdata = head->data;

	int datalen = MAX_BUFFER_SIZE - sizeof(struct file_head);



	//设置数据头中不变的部分

	memset(head, 0, sizeof(struct file_head));

	strcpy(head->filename, strFileName.toLatin1().data());

	head->totallen = file.size();



	//获取数据

	unsigned int len = 0, offset = 0;

	while ((len = file.read(pdata, datalen)) > 0)

	{

		head->offset  = offset;

		head->datalen = len;

		offset += len;

		write((char*)head, sizeof(struct file_head) + len);

		flush();

		waitForBytesWritten();

		//通知进度

		emit writeChanged(strFilePath, ((double)(head->offset + head->datalen) / head->totallen) * 100);

	}

	file.close();

	free(head);



	return 0;

}