A qt client connect with a java server

[parkir]

I have a problem when I am trying to send a msg from my qt client to java server.

this is the java code, the error that i take is " ID ERROR reading: null "
@ public void run() {
System.out.println("Server Thread " + ID + " running.");
while (true) {
try {
server.handle(ID, DataInputStream.readUTF());
}
catch (IOException ioe) {
System.out.println(ID + " ERROR reading: " + ioe.getMessage());
server.remove(ID);
stop();
}
}
}
@

my void in Qt client for send a msg is
@void MainWindow::sendTheMsg()
{
QByteArray buffer;
buffer.append(nickName);
buffer.append(": ");
buffer.append(ui->lineEdit->text());
socket->write("<i>"+buffer+"</i>");
qDebug() << buffer;

}
@

also I have tried to change the encode to UTF8 with this code
@ QString qtext = "Hello";
socket->write(qtext.toUtf8());
@

but nothing!

any idea plz!

[andreyc]

Since you have not provided the initialization part for server nor for client I assume that you checked all possible errors during initialization.

Have you tried to send anything to the Java server from another application, "netcat":http://netcat.sourceforge.net/ or "ncat":http://nmap.org/ncat/ for example?

Have you tried to use the same tools to receive anything from Qt client?

Try to run "wireshark":http://www.wireshark.org/ to see what happens between client and server.

[parkir]

thanks for the reply, I 'll try it I will tell you.

But when I use the Qt client with a server written in Qt, everything is ok and respectively for the java client and server.
I don't know what more changes to make to have a communication between them!

[andreyc]

Another option if you have source code of server.handle(), is to check where is throws an IOException and why its message is null.

[parkir]

my server is the following
chatServer.java
@import java.net.;
import java.io.;

public class ChatServer implements Runnable {
private ChatServerThread clients[] = new ChatServerThread[50];
private ServerSocket server = null;
private Thread thread = null;
private int clientCount = 0;

public ChatServer(int port) {
try {
System.out.println("Binding to port " + port + ", please wait ...");
server = new ServerSocket(port);
System.out.println("Server started: " + server);
start();
} catch (IOException ioe) {
System.out.println("Can not bind to port " + port + ": " + ioe.getMessage());
}
}

public void run() {
while (thread != null) {
try {
System.out.println("Waiting for a client ...");
addThread(server.accept());
} catch (IOException ioe) {
System.out.println("Server accept error: " + ioe);
stop();
}
}
}

public void start() {
if (thread == null) {
thread = new Thread(this);
thread.start();
}
}

public void stop() {
if (thread != null) {
thread.stop();
thread = null;
}
}

private int findClient(int ID) {
for (int i = 0; i < clientCount; i++)
if (clients[i].getID() == ID)
return i;
return -1;
}

public synchronized void handle(int ID, String input) {
if (input.equals(".bye")) {
clients[findClient(ID)].send(".bye");
remove(ID);
} else
for (int i = 0; i < clientCount; i++)
clients[i].send(ID + ": " + input);
}

public synchronized void remove(int ID) {
int pos = findClient(ID);
if (pos >= 0) {
ChatServerThread toTerminate = clients[pos];
System.out.println("Removing client thread " + ID + " at " + pos);
if (pos < clientCount - 1)
for (int i = pos + 1; i < clientCount; i++)
clients[i - 1] = clients[i];
clientCount--;
try {
toTerminate.close();
} catch (IOException ioe) {
System.out.println("Error closing thread: " + ioe);
}
toTerminate.stop();
}
}

private void addThread(Socket socket) {
if (clientCount < clients.length) {
System.out.println("Client accepted: " + socket);
clients[clientCount] = new ChatServerThread(this, socket);
try {
clients[clientCount].open();
clients[clientCount].start();
clientCount++;
} catch (IOException ioe) {
System.out.println("Error opening thread: " + ioe);
}
} else
System.out.println("Client refused: maximum " + clients.length + " reached.");
}

public static void main(String args[]) {
ChatServer server = null;
if (args.length != 1)
System.out.println("Usage: java ChatServer port");
else
server = new ChatServer(Integer.parseInt(args[0]));
}

}
@

and ChatServerThread.java
@import java.net.;
import java.io.;

public class ChatServerThread extends Thread {
private ChatServer server = null;
private Socket socket = null;
private int ID = -1;
private DataInputStream streamIn = null;
private DataOutputStream streamOut = null;

public ChatServerThread(ChatServer _server, Socket _socket) {
super();
server = _server;
socket = _socket;
ID = socket.getPort();
}

public void send(String msg) {
try {
streamOut.writeUTF(msg);
streamOut.flush();
streamOut.writeUTF("writeUTF");
streamOut.writeInt(1234);

} catch (IOException ioe) {
System.out.println(ID + " ERROR sending: " + ioe.getMessage());
server.remove(ID);
stop();
}
}

public int getID() {
return ID;
}

public void run() {
System.out.println("Server Thread " + ID + " running.");
while (true) {
try {
server.handle(ID, streamIn.readUTF());
} catch (IOException ioe) {
System.out.println(ID + " ERROR reading: " + ioe.getMessage());
server.remove(ID);
stop();
}
}
}

public void open() throws IOException {
streamIn = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
streamOut = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
}

public void close() throws IOException {
if (socket != null)
socket.close();

if (streamIn != null)
streamIn.close();

if (streamOut != null)
streamOut.close();
}
}
@

but I cant change the code of server..only the client side which is written in Qt.

[andreyc]

What you will get if you try to read input without processing it.
@
public void run() {
System.out.println("Server Thread " + ID + " running.");
while (true) {
try {
System.out.println(streamIn.readUTF());
//server.handle(ID, streamIn.readUTF());
} catch (IOException ioe) {
System.out.println(ID + " ERROR reading: " + ioe.getMessage());
server.remove(ID);
stop();
}
}
}
@

[EDIT] Did you try to use wireshark and, or netcat?

[parkir]

sr but I dont understand how to use both of them.

[parkir]

I tried your changes but nothing!
It goes to catch.

The error display when I close the client!

[andreyc]

Have you tried another client like ncat or netcat ?
Have you tried wireshark to see what is sent ?

[quote author="parkir" date="1407169299"]But when I use the Qt client with a server written in Qt, everything is ok and respectively for the java client and server.[/quote]

You can compare what is sent between a Java client and Java Server with Qt client and Java server using wireshark.

[parkir]

With the wireshark i can't understand whta happen and how to run but I am running the Zenmap, tell me what parameters to insert to give you the results..

[andreyc]

IIRC(If I Memeber Correctly) Zenmap is for scanning the computer ports not for sniffing a traffic.

But anyway. I tested your java code and simple client. My client connects to server, sends text and disconnect.

I see that client connect to java server and sends text and disconnect.
The error message 55130 ERROR reading: null appears when a client is disconnected, which is ok.

The same happens if I use ncat.

I don't see that ChatServer::handle() is called. I guess something should be done in the server to process the input.

[andreyc]

Here is modified ChatServerThread.java that works.
At least as I think it should work.

• ChatServerThread.java
  @
  import java.net.;
  import java.io.;

public class ChatServerThread extends Thread
{
private ChatServer server = null;
private Socket socket = null;
private int ID = -1;
private BufferedReader streamIn = null;
private BufferedWriter streamOut = null;

public ChatServerThread(ChatServer _server, Socket _socket)
{
super();
server = _server;
socket = _socket;
ID = socket.getPort();
}

public void send(String msg)
{
try {
streamOut.write(msg + "\n");
streamOut.flush();
}
catch (IOException ioe) {
System.out.println(ID + " ERROR sending: " + ioe.getMessage());
server.remove(ID);
stop();
}
}

public int getID()
{
return ID;
}

public void run()
{
System.out.println("Server Thread " + ID + " running.");
while (true) {
try {
String input = streamIn.readLine();
if (input != null) {
server.handle(ID, input);
} else {
System.out.println(ID + " we lost the client :-(.\n");
server.remove(ID);
stop();
}
}
catch (IOException ioe) {
System.out.println(ID + " ERROR reading: " + ioe.getMessage());
server.remove(ID);
stop();
}
}
}

public void open() throws IOException
{
streamIn =
new BufferedReader(new InputStreamReader(socket.getInputStream()));
streamOut =
new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
}

public void close() throws IOException
{
if (socket != null)
socket.close();

if (streamIn != null)
  streamIn.close();

if (streamOut != null)
  streamOut.close();

}
}
@

[parkir]

I think so the problem is the client..

I post you the mainwindow.cpp

@#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QStackedWidget>
#include "about.h"
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);

//set background color
setStyleSheet("background-color: rgb(87,87,87)");

//the login group
ui->loginGroup->setStyleSheet("background-color: rgb(112,128,144); color:white");

//button
ui->btn_login->setStyleSheet("QPushButton { background-color: rgb(176,196,222); color:black }");
ui->btnSend->setStyleSheet("QPushButton { background-color: rgb(176,196,222); color:black }");

//label
ui->label_welcome->setStyleSheet("QLabel {font-family:Pristina; font-size: 30px; color:white;}");

//QlineEdit
ui->txt_nickname->setStyleSheet("QLineEdit {background-color: white; color:black}");
ui->txt_serverIP->setStyleSheet("QLineEdit {background-color: white; color:black}");
ui->msgArea->setStyleSheet("QLineEdit {background-color: white; color:black}");

//the place who display everything from the chat room
ui->roomTextMsg->setStyleSheet("background-color: rgb(112,128,144); color:white");

//set the IP of my server
ui->txt_serverIP->setText("localhost");

//menu bar
ui->menuAbout->setStyleSheet("background-color: rgb(112,128,144); color:white");

socket = new QTcpSocket(this);

ui->stackedWidget->setCurrentWidget(ui->loginPage);

//socket->write(QString("\n"+nickName ).toUtf8());

connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
connect(socket, SIGNAL(connected()), this, SLOT(connected()));

}

MainWindow::~MainWindow()
{
delete ui;
thread->deleteLater();
}

void MainWindow::displayMsg(QByteArray sentMsg)
{
QString msg = QString(sentMsg.data());
ui->roomTextMsg->append(msg);
}

void MainWindow::sendTheMsg()
{
QByteArray buffer;
buffer.append(nickName);
buffer.append(": ");
buffer.append(ui->msgArea->text());
socket->write("<i>"+ buffer +"</i>");
qDebug() << buffer;

ui->msgArea->clear();

}

void MainWindow::on_btnSend_clicked()
{
if( !(ui->msgArea->text() == ""))
{
sendTheMsg();
}
}

void MainWindow::readyRead()
{
thread = new QThread();
ui->roomTextMsg->append(socket->readAll());
socket->flush();
socket->waitForBytesWritten(3000);

socket->moveToThread(thread);
thread->start();

}

void MainWindow::on_btn_login_clicked()
{
nickName = ui->txt_nickname->text().trimmed();

socket->connectToHost(ui->txt_serverIP->text(), 1234);
socket->waitForConnected(3000);

}

void MainWindow::connected()
{
// Flip over to the chat page:
ui->stackedWidget->setCurrentWidget(ui->chatRoom);

// And send our username to the chat server.
socket->write(QString("\n"+nickName + " ..connected\n").toUtf8());

--}

void MainWindow::on_msgArea_returnPressed()
{
if( !(ui->msgArea->text() == ""))
{
sendTheMsg();
}
}
@
this is the client code..this code I have to change and me it to communicate with the server..but I cant find why cannot send and recieve a msg

[parkir]

Did you find a solution andreyc?

[andreyc]

No, unfortunately nothing.