Qt，从客户端发送多个数据类型到服务器+数据流 [英] Qt, Sending multiple data types from client to server + data Streaming
问题描述
我有一个使用QTcpServer和QTcpSocket的基于客户端/服务器的 Qt 应用程序，我设法进行连接，并在客户端和服务器。
客户端向服务器发送多种类型的数据（string，int，文件和实时音频流），并且由于我的服务器使用单个数据输入SLOT（readyRead（））：
I have a Client/Server based Qt application, using QTcpServer and QTcpSocket, I managed to do the connection and send some data back and forth between the client and the server. The client sends many types of data to the server (string, int, files and a real time audio stream) and since my server impliment a single data input SLOT (readyRead()):
connect(socket, SIGNAL(readyRead()),this, SLOT(readyRead()));
我不知道如何区分所有这些接收到的数据并分别调用正确的函数
I don't know how could I distinguish between all this received data and call respectively the right function in the server.
Example (in the server):
- if I receive string => call function showData(QString data);
- if I receive file => call function saveFile(QFile file);
- if I receive audio stream => play audio stream
- ...
SERVER： / p>
SERVER:
void Server::newClientConnection()
{
QTcpSocket *socket = server->nextPendingConnection();
connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
//...
}
void Server::readyRead()
{
QTcpSocket *clientSocket = qobject_cast<QTcpSocket *>(sender());
if (clientSocket == 0) {
return;
}
QDataStream in(clientSocket);
if (sizeMessageClient == 0)
{
if (clientSocket->bytesAvailable() < (int)sizeof(quint16)){
return;
}
in >> sizeMessageClient;
}
if (clientSocket->bytesAvailable() < sizeMessageClient) {
return;
}
sizeMessageClient = 0;
in >> data;
/*
I don't know the type of the received data !!
- if I receive string => call function showData(QString data);
- if I receive file => call function saveFile(QFile file);
- if I receive audio stream => play audio stream
- ...
*/
}
客户：
Client::Client()
{
socket = new QTcpSocket(this);
connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
sizeMessageServer = 0;
}
void Client::readyRead()
{
QDataStream in(socket);
if (sizeMessageServer == 0)
{
if (socket->bytesAvailable() < (int)sizeof(quint16)) {
return;
}
in >> sizeMessageServer;
}
if (socket->bytesAvailable() < sizeMessageServer) {
return;
}
int messageReceived;
in >> messageReceived;
messageReceived = static_cast<int>(messageReceived);
sizeMessageServer = 0;
switch(messageReceived)
{
case 1:
qDebug() << "send a File";
sendFile();
break;
case 2:
qDebug() << "send a string data";
sendStringData();
break;
case 3:
qDebug() << "stream audio to the server";
streamAudioToServer();
break;
case n:
// ...
}
}
我不是在寻找一个完整的解决方案，我所寻找的是一个正确的方向的指导。
I am not looking for a complete solution, all I am looking for is some guidance in the right direction.
推荐答案
p>您的协议的实现没有充分利用Qt 5.7中的 QDataStream 。
The implementation of your protocol doesn't fully leverage QDataStream in Qt 5.7. Here's how it might look now - it can be quite simple.
首先，我们定义我们所知道的请求：
First, let's define the requests we know of:
enum class Req : quint32 {
Unknown, String, File
};
Q_DECLARE_METATYPE(Req)
QDataStream & operator<<(QDataStream & ds, Req req) {
return ds << (quint32)req;
}
QDataStream & operator>>(QDataStream & ds, Req & req) {
quint32 val;
ds >> val;
if (ds.status() == QDataStream::Ok)
req = Req(val);
return ds;
}
这将有助于拥有一个事务RAII助手。
It'd also be handy to have a transaction RAII helper.
struct Transaction {
QDataStream & stream;
Transaction(QDataStream & stream) : stream{stream} {
stream.startTransaction();
}
~Transaction() {
stream.commitTransaction();
}
bool ok() {
return stream.status() == QDataStream::Ok;
}
};
客户端接收来自服务器的请求并发出需要用数据回复的消息。使用客户端的代码将对这些信号做出反应，并通过调用匹配的插槽来回复。例如
The client receives requests from the server and signals the need to reply with data. The code that uses the client would react to these signals and reply back by invoking a matching slot. E.g.
void clientUser(Client & client) {
QObject::connect(&client, &Client::needString, &client, [&]{
client.sendString(QStringLiteral{"You got string!"});
});
和：
class Client : public QObject {
Q_OBJECT
QIODevice & m_dev;
QDataStream m_str{&m_dev};
void onReadyRead() {
Transaction tr{m_str};
Req req;
m_str >> req;
if (!tr.ok()) return;
if (req == Req::String)
emit needString();
else if (req == Req::File) {
QString fileName;
m_str >> fileName;
if (!tr.ok()) return;
emit needFile(fileName);
}
else emit unknownRequest(req);
}
public:
Client(QIODevice & dev) : m_dev{dev} {
connect(&m_dev, &QIODevice::readyRead, this, &Client::onReadyRead);
}
Q_SIGNAL void unknownRequest(Req);
Q_SIGNAL void needString();
Q_SIGNAL void needFile(const QString & fileName);
Q_SLOT void sendString(const QString & str) {
m_str << Req::String << str;
}
Q_SLOT void sendFile(const QString & fileName, const QByteArray & data) {
m_str << Req::File << fileName << data;
}
};
服务器非常相似。其用户通过请求插槽将请求发送到客户端。一旦服务器从客户端听到，它通过有信号指示它：
The server is very similar. Its user sends the request to a client via request slots. Once the server hears back from the client, it indicates it through the has signals:
class Server : public QObject {
Q_OBJECT
QIODevice & m_dev;
QDataStream m_str{&m_dev};
void onReadyRead() {
Transaction tr{m_str};
Req req;
m_str >> req;
if (!tr.ok()) return;
if (req == Req::String) {
QString str;
m_str >> str;
if (!tr.ok()) return;
emit hasString(str);
}
else if (req == Req::File) {
QString fileName;
QByteArray data;
m_str >> fileName >> data;
if (!tr.ok()) return;
emit hasFile(fileName, data);
}
else emit hasUnknownRequest(req);
}
public:
Server(QIODevice & dev) : m_dev{dev} {
connect(&m_dev, &QIODevice::readyRead, this, &Server::onReadyRead);
}
Q_SIGNAL void hasUnknownRequest(Req);
Q_SIGNAL void hasString(const QString &);
Q_SIGNAL void hasFile(const QString & name, const QByteArray &);
Q_SLOT void requestString() {
m_str << Req::String;
}
Q_SLOT void requestFile(const QString & name) {
m_str << Req::File << name;
}
};
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