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Java Socket Server with PHP client

the question is totally rewritten since I have understood that previously it was really unclear.
I have created a Java Socket server with threads to accept multiple connection in order to handle php tcp requests.
The java server just for the testing purposes it reverse the string supplied from php.
Java server is hosted on a ubuntu server and the php is located on another machine.
The java server shows that php client is connected, but the php is not loading and the string is not sent.
From the codes given below what could be the mistake?
UPDATE
the problem is the received string from the Java server. I have checked with debugger and the BufferedReader is full of '\u0000' and server stops responding. The rest code and communication is working perfect.
How I can avoid those null characters or decode the string correct?
ReverseServer
import java.io.*;
import java.net.*;
public class ReverseServer {
public static void main(String[] args) {
int port = 10007;
try (ServerSocket serverSocket = new ServerSocket(port)) {
System.out.println("Server is listening on port " + port);
while (true) {
Socket socket = serverSocket.accept();
System.out.println("New client connected");
new ServerThread(socket).start();
}
} catch (IOException ex) {
System.out.println("Server exception: " + ex.getMessage());
ex.printStackTrace();
}
}
}
ServerThread
import java.io.*;
import java.net.*;
public class ServerThread extends Thread {
private Socket socket;
public ServerThread(Socket socket) {
this.socket = socket;
}
public void run() {
try {
InputStream input = socket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
OutputStream output = socket.getOutputStream();
PrintWriter writer = new PrintWriter(output, true);
String text;
do {
text = reader.readLine();
String reverseText = new StringBuilder(text).reverse().toString();
writer.println("Server: " + reverseText);
} while (!text.equals("bye"));
socket.close();
} catch (IOException ex) {
System.out.println("Server exception: " + ex.getMessage());
ex.printStackTrace();
}
}
}
PHP client
<?php
// websocket connection test
$host = "ip_of_server";
$port = 10007;
$message = "Hello";
echo "Message To server :".$message;
$socket = socket_create(AF_INET, SOCK_STREAM, getprotobyname('TCP'));
$result = socket_connect($socket, $host, $port);
if ($result) {
// send string to server
socket_write($socket, $message, strlen($message)) or die("Could not send data to server\n");
// get server response
$result = socket_read($socket, 1024) or die("Could not read server response\n");
echo "Reply From Server :" . $result;
}
socket_close($socket);

I am trying to read a line, but on the string given on the php client didn't had the carriage return symbol "\r".
Once I have put this on the string it works as expected.

Java socket client doesn't detect server messages

I am attempting to run a Java server socket on a remote host which will regularly broadcast messages (determined by external processes) to all connected clients.
The server socket is defined as:
ServerSocket serverSocket = (ServerSocket) ((ServerSocketFactory)ServerSocketFactory.getDefault()).createServerSocket(3050);
while (true) {
Socket socket = serverSocket.accept();
remoteService.addSocket(socket);
}
Which will keep track of the socket connections in an array list. The method below will then be called whenever a broadcast needs to be sent:
public void broadcastMessage(String message){
for (Socket socket : remoteService.getSockets()) {
System.out.println("Sending message: " + message);
PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true);
printWriter.write(message);
}
}
On the client side, the setup is as below:
Socket socket = (Socket) ((SocketFactory) SocketFactory.getDefault()).createSocket(serverHost,portNum);
BufferedReader socketBufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
while (true) {
String message = socketBufferedReader.readLine();
if (message != null && message != "") {
System.out.println("Message received: " + message);
};
}
The server is correctly printing the "Sending message" string as many times as there are clients connected, but none of the client processes print anything. Any idea how to get the clients to properly listen to the socket inputstream?

PrintWrite.println() method will print the String it's given and terminate the line. Using the below on the server side worked:
public void broadcastMessage(String message){
for (Socket socket : remoteService.getSockets()) {
System.out.println("Sending message: " + message);
PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true);
printWriter.println(message);
}
}

Java-Client PHP-Server UDP Hole Punching example code

I'm working on a project that will require ea p2p server, but I haven't found any java-client php-server example code. I understand the concept of how udp hole punching works but I can't get anything to work in code.
What I've tried:
TheSocket.java
public class TheSocket {
public static String response = "hello";
public static String request;
public static String webServerAddress;
public static ServerSocket s;
protected static ServerSocket getServerSocket(int port)throws Exception{
return new ServerSocket(port);
}
public static void handleRequest(Socket s){
BufferedReader is;
PrintWriter os;
try{
webServerAddress = s.getInetAddress().toString();
is = new BufferedReader(new InputStreamReader(s.getInputStream()));
request = is.readLine();
System.out.println(request);
os = new PrintWriter(s.getOutputStream(), true);
os.println("HTTP/1.0 200");
os.println("Content-type: text/html");
os.println("Server-name: TheSocket");
os.println("Content-length: " + response.length());
os.println("");
os.println(response);
os.flush();
os.close();
s.close();
}catch(Exception e){
System.out.println("Failed to send response to client: " + e.getMessage());
}finally{
if(s != null){
try{
s.close();
}catch(Exception e){
e.printStackTrace();
}
}
}
return;
}
}
Main.java
public class Main {
public static void main(String[] args)throws Exception{
TheSocket.s = TheSocket.getServerSocket(6789);
while(true){
Socket serverSocket = TheSocket.s.accept();
TheSocket.handleRequest(serverSocket);
}
}
PHP-CONNECT.php - to get the other users port, I manually connect and use the port shown on webpage.
<?php
echo $_SERVER['REMOTE_ADDR'].':'.$_SERVER['REMOTE_PORT'];
?>
The issue with the code above, is that it cant make it to the socket unless I port forward.
Comment if you have any questions!

I was facing a similar problem. And was trying to solve it in a similar way.
Some parts of your code look wrong to me.
Sockets in Java are made for TCP but the title says UDP. Therefore u should use DatagramSockets.
But then we come to the point where i stuck too. HTTP-Requests use tcp as well, so opening the port with HTTP might lead to a corrupt port, after tcp session was closed. (Just a guess)
public class Main {
public static void main(String[] args) {
try
{
String httpRequest = "GET /index.php HTTP/1.1\n" +
"Host: <PHP SERVER NAME HERE>";
InetAddress IPAddress = InetAddress.getByName(<PHP SERVER IP HERE>);
DatagramSocket clientSocket = new DatagramSocket();
byte[] sendData = new byte[1024];
byte[] receiveData = new byte[1024];
String sentence = httpRequest;
sendData = sentence.getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 80);
clientSocket.send(sendPacket);
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
clientSocket.receive(receivePacket);
String modifiedSentence = new String(receivePacket.getData());
System.out.println("FROM SERVER:" + modifiedSentence);
clientSocket.close();
}catch(Exception e){e.printStackTrace();}
}
}
The Code above theoretically sents a HTTP over UDP request. So that the displayed Port will be the UDP one. In my case i didnt get any response from the PHP Server and stuck at clientSocket.recieve(..) . I guess because the firewall of my webserver is blocking udp packets.
If the code works by anyone i would proceed like this:
save all accessing ips and ports to a DB and list them to the other client.
Write ur Data in DatagramPackets like above to the other client.
I hope this may help. If anyone can get it completly working i would also be interested in it :)

How to use UDP with multiple Clients in Java

I have the following Situation.
I have a Server class.
I have a Client class.
I have a MultiServerThread class.
When a Client connects to a Server, the Server creates a new MultiServerThread, which is processing the Input from the Client. That way I can have multiple Clients. So far so good.
The connection goes via TCP.
A short example:
Server class:
...
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
boolean listening = true;
try {
serverSocket = new ServerSocket(9999);
} catch (IOException e) {
System.err.println("Could not listen on port: " + serverSocket.getLocalPort() + ".");
System.exit(-1);
}
while (listening) {
new MultiServerThread(serverSocket.accept()).start();
}
serverSocket.close();
}
...
Client class:
...
public static void main(String[] args) throws IOException {
socket = new Socket(hostname, port);
out = new PrintWriter(socket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
stdIn = new BufferedReader(new InputStreamReader(System.in));
String fromServer;
String fromUser;
while ((fromServer = in.readLine()) != null) {
System.out.println("Server: " + fromServer);
if (fromServer.equals("Bye.")) {
break;
}
fromUser = stdIn.readLine();
if (fromUser != null) {
System.out.println("Client: " + fromUser);
out.println(fromUser);
}
}
out.close();
in.close();
stdIn.close();
socket.close();
}
...
MultiServerThread class:
...
public MultiServerThread(Socket socket) throws SocketException {
super("MultiServerThread");
this.socket = socket;
// dSocket = new DatagramSocket(4445);
}
public void run() {
try {
PrintWriter myOutput = new PrintWriter(socket.getOutputStream(), true);
BufferedReader myInput = new BufferedReader(new InputStreamReader(socket.getInputStream()));
myOutput.println("Connected to client and ready to accept commands.");
while ((clientInput = myInput.readLine()) != null) {
//A SIMPLE LOGIN A USER
if (clientInput.contains("!login")) {
//save some string given by client into loggedUser
String loggedUser = clientInput.substring(7);
}
myOutput.close();
myInput.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
What I need is:
I need to implement a notification that comes from a Server when for example the Username is "Bob". If the username is "Bob", the server should give a notification to the Client "Bob is here again!". In my project/homework this should be done with datagrams in Java.
So if the clientinput is "!login bob" then a datagram packet with the message ("Bob is here again!") should be sent to the client.
Question: Where exactly should I put the code of the Datagram request in? Can I put the datagram packet request into the MultiServerThread or into the Client?
It would be easier in the MultiServerThread because it already handles the !login.
Here:
if (clientInput.contains("!login")) {
//save some string given by client into loggedUser
String loggedUser = clientInput.substring(7);
//send datagram request to Server???
}
But this is going against the principle of networking?

you need to send the UDP port number to your client through the initial TCP connection. Then you start listening for UDP datagrams on your client on that port number. All other communications from server -> client will be on this udp socket. This is what your assignment suggests

I got it working ;-)
I definied a udp port in the thread and client class...
the client class got his port with arguments... it gave the udp Port to the thread... so both had the udp ports ;)

Cannot communicate with server in Java

I am trying to write server to client program but I cannot communicate with the server in Java.
Here is the code block in my main.
InetAddress addr = InetAddress.getLocalHost();
ipAddress = "78.162.206.164";
ServerSocket serverSocket = new ServerSocket(0);
String randomStringForPlayerName = RandomStringGenerator.generateRandomString();
baseForReqOpp += ipAddress + " " + serverSocket + " " + randomStringForPlayerName;
Socket socket = new Socket(host,2050);
socket.setSoTimeout(100);
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream());
out.write(baseForReqOpp);
out.flush();
System.out.println(in.read());
I know that there is no problem in the server code and all the communication ports are ok.
But I cannot read anything from the server.
What can be the problem?

you have to create an output stream before the input stream

Here is some working code with communicating client and server sockets. Hopefully you can adapt it for your specific problem.
public class SocketTest {
public void runTest() {
try {
// create the server
new SimpleServer().start();
// connect and send a message
InetAddress addr = InetAddress.getLocalHost();
Socket sock = new Socket(addr, 9090);
ObjectOutputStream out = new ObjectOutputStream(sock.getOutputStream());
out.writeObject("Hello server");
out.flush();
ObjectInputStream in = new ObjectInputStream(sock.getInputStream());
System.out.println("from server: " + in.readObject());
sock.close();
} catch (Exception e) {
e.printStackTrace();
}
}
// server has to run in a separate thread so the code doesn't block
private class SimpleServer extends Thread {
#Override
public void run() {
try {
ServerSocket sock = new ServerSocket(9090);
Socket conn = sock.accept();
// the code blocks here until a client connects to the server
ObjectInputStream in = new ObjectInputStream(conn.getInputStream());
System.out.println("from client: " + in.readObject());
ObjectOutputStream out = new ObjectOutputStream(conn.getOutputStream());
out.writeObject("Hello client");
out.flush();
sock.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
To run it:
new SocketTest().runTest();

Your code will never work because you don't use threads. In order to start the server, you need to call accept at some point in your code
myServerSocket.accept();
this is a blocking call, ie the code flow stops until a client connects. But since you can't execute any statement (remember accept is blocking?) how can a client connect? This chicken and egg problem is resolved through threads. See Howard's answer for a code sample.
I don't see any call to accept(), so I wonder what your client connects to...