I'm trying to establish bluetooth connection between laptop and Samsung Smart Touch Remote. My issue is that I can't connect socket to device(socket is always in "Host lookup state"):
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
// Create a discovery agent and connect to its signals
QBluetoothDeviceDiscoveryAgent *discoveryAgent = new QBluetoothDeviceDiscoveryAgent(this);
connect(discoveryAgent, SIGNAL(deviceDiscovered(const QBluetoothDeviceInfo&)),
this, SLOT(deviceDiscovered(const QBluetoothDeviceInfo&)));
// Start a discovery
discoveryAgent->start();
}
void MainWindow::deviceDiscovered(const QBluetoothDeviceInfo &device)
{
socket = new QBluetoothSocket(QBluetoothServiceInfo::RfcommProtocol, this);
socket->connectToService(QBluetoothAddress(device.address()),
QBluetoothUuid(QBluetoothUuid::SerialPort));
connect(socket, SIGNAL(error(QBluetoothSocket::SocketError)),
this, SLOT(socketError(QBluetoothSocket::SocketError)));
connect(socket, SIGNAL(connected()), this, SLOT(socketConnected()));
connect(socket, SIGNAL(disconnected()), this, SLOT(socketDisconnected()));
connect(socket, SIGNAL(readyRead()), this, SLOT(socketRead()));
connect(socket, SIGNAL(stateChanged(QBluetoothSocket::SocketState)), this, SLOT(socketStateChanged()));
}
void MainWindow::socketRead()
{
QByteArray receivedData = socket->readAll();
QMessageBox msg;
msg.setText(QString(receivedData));
msg.exec();
}
void MainWindow::socketConnected()
{
qDebug() << "Socket connected";
qDebug() << "Local: "
<< socket->localName()
<< socket->localAddress().toString()
<< socket->localPort();
qDebug() << "Peer: "
<< socket->peerName()
<< socket->peerAddress().toString()
<< socket->peerPort();
}
void MainWindow::socketDisconnected()
{
qDebug() << "Socket disconnected";
socket->deleteLater();
}
void MainWindow::socketError(QBluetoothSocket::SocketError error)
{
qDebug() << "Socket error: " << error;
}
void MainWindow::socketStateChanged()
{
int socketState = socket->state();
QMessageBox msg;
if(socketState == QAbstractSocket::UnconnectedState)
{
msg.setText("unconnected");
}
else if(socketState == QAbstractSocket::HostLookupState)
{
msg.setText("host lookup");
}
else if(socketState == QAbstractSocket::ConnectingState )
{
msg.setText("connecting");
}
else if(socketState == QAbstractSocket::ConnectedState)
{
msg.setText("connected");
}
else if(socketState == QAbstractSocket::BoundState)
{
msg.setText("bound");
}
else if(socketState == QAbstractSocket::ClosingState)
{
msg.setText("closing");
}
else if(socketState == QAbstractSocket::ListeningState)
{
msg.setText("listening");
}
msg.exec();
}
Can someone please tell me what I'm doing wrong?
Have you tried to open a COM port on your Laptop which is connected to the Laptop's bluetooth module?
You can go to Bluetooth settings -> Com Ports -> Add a new com port. Then open this Port using hypertermical or Teraterm. Now try to connect from your Android phone...
Hope this works!
I had the samme issue. The fix was to use a port 1 in argument to socket->connectToService(addr, 1).
This tells SDP to use connection as channel via SDP.
Related
I am making a simple program that will 'connect' to itself and then send data. It starts a QTcpServer then waits for any incoming connections. I have a separate function that will in turn attempt to connect to this server at the localhost and port I decided on. This works when I open Telnet in the command prompt, but now in my actual program. Here is the code that I used (Some are snippets from other sources)
MainWindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
server = new QTcpServer(this);
//Initialize and start the server
connect(server, SIGNAL(newConnection()), this, SLOT(newConnection()));
if (!server->listen(QHostAddress::Any, 3665))
{
qDebug() << "Server failed to start!";
}
else
{
qDebug() << "Server started";
}
//Try to connect to the server
connectToServer("127.0.0.1", qint16(3665));
}
MainWindow::~MainWindow()
{
delete server;
delete ui;
}
void MainWindow::connectToServer(QString host, qint16 port)
{
qDebug() << "Connecting to " + host + " at port " + QString::number(port);
QTcpSocket socket;
socket.connectToHost(host, port);
if (!socket.waitForConnected(5000))
{
qDebug() << socket.errorString();
}
while (socket.bytesAvailable() < (int)sizeof(quint16))
{
if (!socket.waitForReadyRead(5000))
{
qDebug() << socket.errorString();
}
}
quint16 blockSize;
QDataStream in(&socket);
in.setVersion(QDataStream::Qt_5_5);
in >> blockSize;
while (socket.bytesAvailable() < blockSize)
{
if (!socket.waitForReadyRead(5000))
{
qDebug() << socket.errorString();
}
}
QString fortune;
in >> fortune;
qDebug() << fortune;
}
void MainWindow::newConnection()
{
qDebug() << "A connection has been found.";
QTcpSocket *socket = server->nextPendingConnection();
socket->write("hello client\r\n");
socket->flush();
socket->waitForBytesWritten(5000);
socket->close();
}
The source of your problem is, most likely, the pseudo-synchronous mess caused by waitFor methods. Get rid of them. Furthermore, you're not guaranteed anything about how many bytes you receive upon readyRead: it's perfectly normal to receive one byte at a time, in some circumstances, or really any number of bytes, including more bytes than you might expect. Your code must cope with that.
This is one example of such approach - it does what you want, asynchronously.
That is another example that shows how to leverage state machines to write asynchronous communications code using an easy to read, declarative syntax.
I am writing simple client server program in Qt that server is multi thread.
For one server it work correctly and it can send message from client to server but in multi thread form it doesn't work, it connect to thread and also show the message "client connected" but it can't show message sent from client!
I searched a lot bud I couldn't find what is the problem and any solution for it.. Here is my code:
Could you please help me. Thanks in advance.
myserver.cpp
#include "myserver.h"
#include "mythread.h"
myserver::myserver(QObject * parent): QTcpServer(parent)
{
}
void myserver::startserver()
{
int port = 6666;
if (!this - > listen(QHostAddress::Any, port)) {
qDebug() << "Could not start server ";
} else {
qDebug() << "Listening to port ";
}
}
void myserver::incomingConnection(qintptr socketDescriptor)
{
qDebug() << socketDescriptor << " Connecting...";
mythread * thread = new mythread(socketDescriptor, this);
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
thread - > start();
}
mythread.cpp
#include "mythread.h"
#include "myserver.h"
mythread::mythread(qintptr ID, QObject *parent) : QThread(parent)
{
this->socketDescriptor = ID;
}
void mythread::run()
{
qDebug() << " Thread started";
socket = new QTcpSocket();
if(!socket->setSocketDescriptor(this->socketDescriptor)) {
emit error(socket->error());
return;
}
connect(socket, SIGNAL(readyRead()), this, SLOT(readSocket()));
qDebug() << socketDescriptor << " Client connected";
}
void mythread::readSocket()
{
QByteArray Data = socket->readAll();
qDebug()<< socketDescriptor <<" Data in: " << Data;
socket->write(Data);
}
If you read the documentation for the QThread::run function you will see
Returning from this method will end the execution of the thread.
You need to call the QThread::exec function to enter the thread event loop.
I am writing multi thread server but i have problem in accept connection and start read function. i don't know where i should write them..
here is my code:
"mythread.cpp"
#include "mythread.h"
#include "myserver.h"
mythread::mythread(qintptr ID, QObject *parent) :
QThread(parent)
{
this->socketDescriptor = ID;
}
void mythread::run()
{
qDebug() << " Thread started";
}
void mythread::acceptConnection()
{
c_client = s_server.nextPendingConnection();
connect(c_client,SIGNAL(readyRead()),
this, SLOT(startRead()));
}
void mythread::startRead()
{
char buffer[1024] = {0};
c_client->read(buffer, c_client->bytesAvailable());
qDebug() << buffer;
}
void mythread::readyRead()
{
QByteArray Data = socket->readAll();
qDebug() << socketDescriptor << " Data in: " << Data;
socket->write(Data);
}
void mythread::disconnected()
{
qDebug() << socketDescriptor << " Disconnected";
socket->deleteLater();
exit(0);
}
"myserver.cpp"
#include "myserver.h"
#include "mythread.h"
myserver::myserver(QObject *parent) :
QObject(parent)
{
}
void myserver::startserver()
{
int port = 1234;
if(s_server.listen(QHostAddress::Any, port))
{
qDebug() << "Could not start server";
}
else
{
qDebug() << "Listening to port " << port ;
}
}
void myserver::incomingconnection(int socketDescriptor)
{
connect(&s_server, SIGNAL(newConnection()),
this, SLOT(acceptConnection()));
s_server.listen(QHostAddress::Any, 1234);
qDebug() << socketDescriptor << " Connecting...";
mythread *thread = new mythread(socketDescriptor,this);
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
thread->start();
}
i would be grateful if you help me.
You are not using QThread very well. you can use SIGNAL and SLOTS ,and MoveToThread() function. google it.
when you use QThread, the code in Run() function will be run in another thread. acceptConnection will run in main thread.
also search for nextPendingConnection();
void myserver::incomingconnection(int socketDescriptor)
{
connect(&s_server, SIGNAL(newConnection()),this, SLOT(acceptConnection()));
...
is not OK. this connect should be called once (maybe constructor). not for any incomming connection.
I have a server that can handle multiple threads. The server starts and listens, but it is having trouble echoing when an incoming connection is pending.
I am using telnet to open the socket and send data to the server. However, the server only displays that it's listening, but doesn't echo any of the data I type through telnet or signify that there is an incoming connection. I shut off Windows firewall for private networks and still...nothing.
Also tried seeing if the server error string had anything useful to say, but all it is just an empty string.
This is a complete mystery to me and if anyone had anything constructive to note, it'd be much appreciated. Code for the thread and server is below.
server.cpp
#include "myserver.h"
MyServer::MyServer(QObject *parent) :
QTcpServer(parent)
{
}
void MyServer::StartServer()
{
if(!this->listen(QHostAddress::Any,1234))
{
qDebug() << "Could not start server";
}
else
{
qDebug() << "Listening...";
}
}
void MyServer::incomingConnection(int socketDescriptor)
{
qDebug() << socketDescriptor << " Connecting...";
MyThread *thread = new MyThread(socketDescriptor,this);
connect(thread, SIGNAL(finished()),thread, SLOT(deleteLater()));
thread->start();
}
thread.cpp
#include "mythread.h"
MyThread::MyThread(int ID, QObject *parent) :
QThread(parent)
{ this->socketDescriptor = ID;
}
void MyThread::run()
{
qDebug() << socket->errorString();
//thread starts here
qDebug() << socketDescriptor << " Starting thread";
socket = new QTcpSocket();
if(!socket->setSocketDescriptor(this->socketDescriptor))
{
emit error(socket->error());
return;
}
connect(socket,SIGNAL(readyRead()),this,SLOT(readyRead()),Qt::DirectConnection);
connect(socket,SIGNAL(disconnected()),this,SLOT(disconnected()),Qt::DirectConnection);
qDebug() << socketDescriptor << " Client Connected";
exec();
}
void MyThread::readyRead()
{
QByteArray Data = socket->readAll();
qDebug() << socketDescriptor << " Data in: " << Data;
socket->write(Data);
}
void MyThread::disconnected()
{
qDebug() << socketDescriptor << " Disconnected";
socket->deleteLater();
exit(0);
}
Which version of Qt are you using? In Qt 5, the parameter for the function incomingConnection is of type qintptr and not int. Have a look at the following links:
incomingConnection - Qt 5
Qt 5 - Multithreaded server tutorial
Programm works, but client can't connect to the server. (i run 2 examples of programm: client and server). I can't find where is my mistake.
I wrote the codes below.You will see what i want to do if you look at main function.
//main.cpp
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
//выбор клиента или сервера
cout << "1.Client\n2.Server\n";
switch (_getch())
{
case 49:
{
cout<<"client init\n";
Client* cli = new Client("localhost",1922);
string line;
while(line!="exit") {
cout << "Message : ";
cin >> line;
cli->SendData(QString(line.c_str()));
}
break;
}
case 50:
{
cout<<"server init\n";
Server* srv = new Server(0, 1922);
break;
}
}
return a.exec();
}
//server.h
class Server : public QTcpServer {
Q_OBJECT public : Server(QObject *parent = 0, quint16 port = 1922);
virtual ~Server();
private
slots:
void acceptConnection();
void startRead();
void disconnected();
private:
QTcpServer *tcpServer;
QTcpSocket *client;
};
//server.cpp
Server::Server(QObject *parent, quint16 port) : QTcpServer(parent) {
//tcpServer = new QTcpServer(this);
connect(this, SIGNAL(newConnection()), this, SLOT(acceptConnection()));
if (!this->listen(QHostAddress::Any, port))
std::cout << "unable to start server\n"
<< this->errorString().toUtf8().constData() << endl;
else
std::cout << "server started\n";
}
Server::~Server() {
//delete client;
close();
}
void Server::acceptConnection() {
std::cout << "new connection!\n";
client = nextPendingConnection();
connect(client, SIGNAL(readyRead()), this, SLOT(startRead()));
connect(client, SIGNAL(disconnected()), this, SLOT(disconnected()));
qDebug() << "New client from:" << client->peerAddress().toString();
}
void Server::startRead() {
client = (QTcpSocket *)sender();
while (client->canReadLine()) {
QString line = QString::fromUtf8(client->readLine()).trimmed();
qDebug() << "Client :" << line;
client->write(QString("Server : I've taken your message (:\n").toUtf8());
}
}
void Server::disconnected() {
qDebug() << "Client disconnected:" << client->peerAddress().toString();
client->write(QString("Server : I wish you didn't leave ):\n").toUtf8());
}
//} <-- EDIT: THIS IS PROBABLY AN EXTRA
//***************************************************************
//client.h
class Client : public QObject {
Q_OBJECT public : Client(const QString &add, int port, QObject *obj = 0);
void SendData(QString data);
virtual ~Client();
int status();
QString err;
private
slots:
void ReadData();
void slotConnected();
void slotError(QAbstractSocket::SocketError);
private:
QTcpSocket *socket;
};
//client.cpp
Client::Client(const QString &add, int port, QObject *obj) : QObject(obj) {
//create socket
socket = new QTcpSocket(this);
//connect
socket ->connectToHost(add, port);
connect(socket, SIGNAL(readyRead()), SLOT(ReadData()));
connect(socket, SIGNAL(connected()), SLOT(slotConnected()));
connect(socket, SIGNAL(error(QAbstractSocket::SocketError)), this,
SLOT(slotError(QAbstractSocket::SocketError)));
}
Client::~Client() {
socket->close();
delete socket;
}
void Client::SendData(QString data) {
if (!data.isEmpty()) {
QByteArray arrBlock;
QDataStream out(&arrBlock, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_5_1);
out << quint16(0) << QTime::currentTime() << data;
out.device()->seek(0);
out << quint16(arrBlock.size() - sizeof(quint16));
socket->write(arrBlock);
socket->flush();
}
}
void Client::ReadData() {
QDataStream in(socket);
in.setVersion(QDataStream::Qt_5_1);
while (socket->canReadLine()) {
QString line = QString::fromUtf8(socket->readLine()).trimmed();
qDebug() << line;
}
}
void Client::slotConnected() {
socket->write(QString("Client : Server connection has been made (: \n")
.toUtf8());
}
void Client::slotError(QAbstractSocket::SocketError err) {
QString strError =
"Error: " + (err == QAbstractSocket::HostNotFoundError
? "The host was not found."
: err == QAbstractSocket::RemoteHostClosedError
? "The remote host is closed."
: err == QAbstractSocket::ConnectionRefusedError
? "The connection was refused."
: QString(socket->errorString()));
std::cout << strError.toUtf8().constData() << endl;
}
int Client::status() { return socket->state(); }
help me pls!
It's probably becouse of the while loop in main.cpp, it blocks client's event loop, and will return to event loop right after 'exit' will be typed. I mean this lines:
while (line != "exit") {
cout << "Message : ";
cin >> line;
cli.SendData(QString(line.c_str()));
}
How this can be avoided: main.cpp MUST reach return a.exec(); line to start event loop (i am excluding some ugly processEvent solutions right away ).
To send commands to cmd and NOT block event loop i used class i saw somewhere here on stackoverflow:
example of main.cpp:
QCoreApplication a(argc, argv);
qDebug()<<"Press 'q' to quit";
QTcpServer server;
qDebug()<<"Server is started -"<<server.isListening();
// Console reader to filter console input
ConsoleReader reader;
QObject::connect(&reader,SIGNAL(shutdown()),&a,SLOT(quit()));
return a.exec();
aaand behold, ConsoleReader class, header:
#ifndef CONSOLEREADER_H
#define CONSOLEREADER_H
#pragma once
#include <QObject>
#include <QSocketNotifier>
class ConsoleReader : public QObject
{
Q_OBJECT
public:
explicit ConsoleReader(QObject *parent = 0);
~ConsoleReader();
signals:
void shutdown();
public slots:
void text();
private:
QSocketNotifier* notifier;
};
#endif // CONSOLEREADER_H
source:
#include "consolereader.h"
#include <QTextStream>
#include <QDebug>
#include <unistd.h> //Provides STDIN_FILENO
ConsoleReader::ConsoleReader(QObject *parent) :
QObject(parent)
{
notifier = new QSocketNotifier(STDIN_FILENO, QSocketNotifier::Read);
connect(notifier, SIGNAL(activated(int)), this, SLOT(text()));
}
void ConsoleReader::text()
{
QTextStream qin(stdin);
QString line = qin.readLine();
if (line==QString("q")){
qDebug()<<"Shutting down the server..";
emit shutdown();
}
else qDebug()<<"Unknown command: "<<line;
}
ConsoleReader::~ConsoleReader(){
delete notifier;
}
In your main function, you create both the client and the server on the stack, which will then be deleted when they go out of scope of the switch statement.
You need to dynamically allocate the objects on the heap: -
Server* pServer = new Server(0, 1922);
Client* pClient = new Client("localhost" 1922);
Although the client will remain, due to the while loop after its creation, the server will be created, start listening, then be deleted, along with the QTcpSocket, as it is has the server as its parent.
As I mentioned in my comment there is no need to create a separate QTCpServer as the server isa QTcpServer. So where you have:
Server::Server(QObject *parent, quint16 port) : QTcpServer(parent) {
tcpServer = new QTcpServer(this);
connect(this, SIGNAL(newConnection()), this, SLOT(acceptConnection()));
if (!tcpServer->listen(QHostAddress::Any, port))
std::cout << "unable to start server\n"
<< tcpServer->errorString().toUtf8().constData() << endl;
else
std::cout << "server started\n";
}
Change to:
Server::Server(QObject *parent, quint16 port) : QTcpServer(parent) {
connect(this, SIGNAL(newConnection()), this, SLOT(acceptConnection()));
if (!this->listen(QHostAddress::Any, port))
std::cout << "unable to start server\n"
<< this->errorString().toUtf8().constData() << endl;
else
std::cout << "server started\n";
}
I think the problem could be that its trying to do stuff with a different object rather than the 'this' object.