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How to connect react native app to java server

I've created a java server app which opens connections with serverSocket on port 3000 and it works perfectly with java client app I created. But now I started developing client app in react native and I can't understand it's socket API, because socket.io in react native forces me to use WebSocket way.
Is there any other way?
public static final int PORT = 3000;
private ServerSocket mServerSocket = null;
#Override
public void run() {
try {
mServerSocket = new ServerSocket(PORT);
} catch (IOException e) {
close();
return;
}
while (isOpen()) {
try {
mSocket = mServerSocket.accept();
ClientThread clientThread = new ClientThread(new Client(mSocket, this));
mClients.add(clientThread);
clientThread.start();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
try {
mServerSocket.close();
mSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}

I can not connect to server with Socket.IO-client Java

I want use library
And I wan realize this functionality:
connect to my java server
Socket socket = IO.socket("http://127.0.0.1:4444");
socket.io().open(new Manager.OpenCallback() {
#Override
public void call(Exception err) {
if (err != null) {
Log.d("mylog", err.getMessage());
return;
}
Log.d("mylog", "connected");
}
});
Send messge - I do not understand how.
It is my server:
public class Server {
public static void main(String[] args) throws IOException {
System.out.println("Welcome to Server side");
BufferedReader in = null;
PrintWriter out= null;
ServerSocket servers = null;
Socket fromclient = null;
// create server socket
try {
servers = new ServerSocket(4444);
} catch (IOException e) {
System.out.println("Couldn't listen to port 4444");
System.exit(-1);
}
try {
System.out.print("Waiting for a client...");
fromclient= servers.accept();
System.out.println("Client connected");
} catch (IOException e) {
System.out.println("Can't accept");
System.exit(-1);
}
in = new BufferedReader(new
InputStreamReader(fromclient.getInputStream()));
out = new PrintWriter(fromclient.getOutputStream(),true);
String input,output;
System.out.println("Wait for messages");
while ((input = in.readLine()) != null) {
if (input.equalsIgnoreCase("exit")) break;
out.println("S ::: "+input);
System.out.println(input);
}
out.close();
in.close();
fromclient.close();
servers.close();
}
}
If I use Java client I can work with server, but I want to connect to android client. And I found only this library, and I not understand how it work. Examples in site not helped for me.

Make sure you have added its permission in your AndroidManifest.xml
<uses-permission android:name="android.permission.INTERNET" />
Android's kernel, unlike mainline Linux kernel, restricts requests for creating sockets unless that application already has INTERNET permission.
Find more technical information about Android's Paranoid networking option in this link.
UPDATE #1
If you want to connect your Android client to the server on your PC localhost you should not use 127.0.0.1 as server IP address. This is Android its own localhost. You should instead use 10.0.2.2 as server IP address. More Info

#Pavel i've implemented SocketIO client for one of my app
here is the code... i think ..this may help u
private Socket mSocket;
/**
* chat socket connection methods
*/
public void socketConnection()
{
try
{
mSocket = IO.socket(Constant.CHAT_SERVER_URL);
mSocket.on(Socket.EVENT_CONNECT_ERROR, onConnectError);
mSocket.on("message", onSocketConnectionListener);
mSocket.connect();
}
catch (URISyntaxException e)
{
e.printStackTrace();
}
new Thread(new Runnable() {
#Override
public void run() {
while(mSocket.connected()==false)
{
//do nothing
}
sendConnectData();
}
}).start();
}
/**
* Send Data to connect to chat server
*/
public void sendConnectData()
{
JSONObject msgToSend=new JSONObject();
try
{
msgToSend.put("Type", 1);
msgToSend.put("userid", userid);
}
catch (Exception e)
{
e.printStackTrace();
}
mSocket.emit("message", msgToSend);
}
/**
* Listener for socket connection error.. listener registered at the time of socket connection
*/
private Emitter.Listener onConnectError = new Emitter.Listener() {
#Override
public void call(Object... args) {
runOnUiThread(new Runnable() {
#Override
public void run() {
if (mSocket != null)
if (mSocket.connected() == false)
socketConnection();
}
});
}
};
/**
* Listener to handle messages received from chat server of any type... Listener registered at the time of socket connected
*/
private Emitter.Listener onSocketConnectionListener = new Emitter.Listener() {
#Override
public void call(final Object... args) {
runOnUiThread(new Runnable() {
#Override
public void run() {
// handle the response args
}
});
}
};

Java Proxy Socket not connecting to client

I will post my code below, a little background.
I am trying to connect to a gameserver on port 9339. my local port changes each time. The aim is to pass the packets through the proxy and display the info in the command line.
The client connects to the remote host using bluestacks which is running the game.
Code:
import java.io.*;
import java.net.*;
public class proxy {
public static void main(String[] args) throws IOException {
try {
String host = "gamea.clashofclans.com";
int remoteport = 9339;
ServerSocket ss = new ServerSocket(0);
int localport = ss.getLocalPort();
ss.setReuseAddress(true);
// Print a start-up message
System.out.println("Starting proxy for " + host + ":" + remoteport
+ " on port " + localport);
// And start running the server
runServer(host, remoteport, localport,ss); // never returns
System.out.println("Started proxy!");
} catch (Exception e) {
System.err.println(e);
}
}
/**
* runs a single-threaded proxy server on
* the specified local port. It never returns.
*/
public static void runServer(String host, int remoteport, int localport, ServerSocket ss)
throws IOException {
final byte[] request = new byte[2048];
byte[] reply = new byte[4096];
while (true) {
Socket client = null, server = null;
try {
// Wait for a connection on the local port
client = ss.accept();
System.out.println("Client Accepted!");
final InputStream streamFromClient = client.getInputStream();
final OutputStream streamToClient = client.getOutputStream();
// Make a connection to the real server.
// If we cannot connect to the server, send an error to the
// client, disconnect, and continue waiting for connections.
try {
server = new Socket(host, remoteport);
System.out.println("Client connected to server.");
} catch (IOException e) {
PrintWriter out = new PrintWriter(streamToClient);
out.print("Proxy server cannot connect to " + host + ":"
+ remoteport + ":\n" + e + "\n");
out.flush();
client.close();
System.out.println("Client disconnected");
continue;
}
// Get server streams.
final InputStream streamFromServer = server.getInputStream();
final OutputStream streamToServer = server.getOutputStream();
// a thread to read the client's requests and pass them
// to the server. A separate thread for asynchronous.
Thread t = new Thread() {
public void run() {
int bytesRead;
try {
while ((bytesRead = streamFromClient.read(request)) != -1) {
streamToServer.write(request, 0, bytesRead);
streamToServer.flush();
}
} catch (IOException e) {
}
// the client closed the connection to us, so close our
// connection to the server.
try {
streamToServer.close();
} catch (IOException e) {
}
}
};
// Start the client-to-server request thread running
t.start();
// Read the server's responses
// and pass them back to the client.
int bytesRead;
try {
while ((bytesRead = streamFromServer.read(reply)) != -1) {
streamToClient.write(reply, 0, bytesRead);
streamToClient.flush();
}
} catch (IOException e) {
}
// The server closed its connection to us, so we close our
// connection to our client.
streamToClient.close();
} catch (IOException e) {
System.err.println(e);
} finally {
try {
if (server != null)
server.close();
if (client != null)
client.close();
} catch (IOException e) {
}
}
}
}
}
Basically the last thing that is printed out is "Starting proxy for gamea.clashofclans.com:9339 on port (whatever it chose).
Hopefully someone can help me.

I have this problem too, I don`t have enough time to correct this but i think using thread is that is why all mistake.
check your proxy for working on browser setting( May be proxy had problem)
If not,
I suggest to don`t use thread. maybe mutual exclusion occurs.

Your code is correct.It is working fine so you don't need any fix. What is happening is , your serverSocket in your proxy class is waiting for client to connect. that's why it is not going forward. What you need to do is, create a client and connect to it.
follow the step :
run your proxy.
then run your client
for the client, you can use this code,
public static void main(String[] args) throws IOException {
try {
int remoteport = 9339;
String host="127.0.0.1";
makeConnection(host, remoteport);
System.out.println("connection successful!");
} catch (Exception e) {
System.err.println(e);
}
}
public static void makeConnection(String host, int remoteport) throws IOException {
while (true) {
Socket client = null;
try {
client = new Socket(host, remoteport);
System.out.println("Client connected to server.");
break;
} catch (IOException e) {
System.err.println(e);
} finally {
if (client != null)
client.close();
if (client != null)
client.close();
}
}
}

Connect to remote port(Server) from thread in polling

I want to connect to a remote server from thread and keep sending strings. If the connection gets refused the thread should keep polling the port until the server is up again. How can I handle this exception and keep my thread fro crashing? The server may not be up for long time but thread should run indefinitely.
public void SendMessage(String message){
try {
socket = new Socket(actuatorAddress, destPort.get());
outToServer = socket.getOutputStream();
out = new DataOutputStream(outToServer);
out.flush();
out.write(message.getBytes());
} catch (IOException ex) {
System.out.println(ex.getMessage());
} catch (Exception e) {
System.out.println(e.getMessage());
}
}
I changed some part of the code as below. For first time called Connect function and then subsequently called Send Message function through thread. The delay added to reconnecting helped reduce time lag recurred due to connecting to non existing server. Still think that there might be a better solution to the basic problem.
public boolean ConnectToActuator() {
try {
if(actuatorAddress.isReachable(2000)){
socket = new Socket();
socket.setPerformancePreferences(1, 2, 0);
socket.setTcpNoDelay(false);
socket.setSendBufferSize(32);
socket.connect(new InetSocketAddress(actuatorAddress, destPort.get()));
outToServer = socket.getOutputStream();
out = new DataOutputStream(outToServer);
connected = true;
disconnectedTimeout = 0;
}
}catch (ConnectException e) {
// TODO Auto-generated catch block
System.out.println(e.getMessage());
}catch (IOException ex) {
connected = false;
System.out.println(ex.getMessage());
}
return connected;
}
public boolean SendToActuator(String message) {
if(connected == false){ //socket.isOutputShutdown()
disconnectedTimeout++;
if(disconnectedTimeout>20){
disconnectedTimeout = 0;
ConnectToActuator();
} else {
return connected;
}
}
try {
out.flush();
out.writeBytes(message);
disconnectedTimeout = 0;
connected = true;
} catch (UnknownHostException uhe) {
connected = false;
System.out.println(uhe.getMessage());
} catch (IOException ioe) {
connected = false;
System.out.println(ioe.getMessage());
}
return connected;
}

Given the following constraints in the comments:
Try to send the message to one of the 10 servers.
If none of the servers are available to receive the message, discard the message.
What you actually want to do is:
Iterate through a list of server addresses
Attempt to send a message to each of them
Break out of the loop right away if successful
Catch any errors on connection failure and try the next server
Here's an example class that will run through that scenario.
import java.io.DataOutputStream;
import java.io.OutputStream;
import java.net.Socket;
public class MessageSender {
private static final Integer destPort = 1234;
private static final String[] serverAddresses = {
"address1",
"address2",
"address3" // Etc....
};
public Boolean SendMessage(String message) {
Boolean messageSentSuccessfully = false;
for (String addy : serverAddresses) {
messageSentSuccessfully = SendMessageToServer(addy, message);
if (messageSentSuccessfully) {
break;
}
}
return messageSentSuccessfully;
}
private Boolean SendMessageToServer(String serverAddress, String message) {
Boolean messageSent = false;
try {
Socket dataSocket = new Socket(serverAddress, destPort);
OutputStream outToServer = dataSocket.getOutputStream();
DataOutputStream out = new DataOutputStream(outToServer);
out.write(message.getBytes());
out.flush();
messageSent = true;
} catch (Exception e) {
System.out.println(e);
}
return messageSent;
}
}
Hope that helps.

Pseudo:
while(true){
if(connect()) DoClientConnectedStuff();
sleep(reconnectTimeout);
};

please try below changes. if your connection refuses it will wait for 2s(2000ms) and then again try to connect with server. if connection being successful it will take outputstream, write data in a while loop and flush the data.
public void createSocketConnection() throws IOException
{
socket = new Socket(actuatorAddress, destPort.get());
if(socket!=null)
{
outToServer = socket.getOutputStream();
out = new DataOutputStream(outToServer);
}
}
public void SendMessage(String message){
boolean isRunning=false;
try
{
createSocketConnection();
isRunning=true;
while(isRunning)
{
out.write(message.getBytes());
out.flush();
}
} catch (java.net.ConnectException conExcp) {
System.out.println(ex.getMessage());
try{
Thread.sleep(2000);
}catch(Exception ee){}
}
catch (IOException ex) {
System.out.println(ex.getMessage());
}
}

Server is only reading the first object that is sent from the client

I'm having issues sending objects to a server. Right now, I have a server setup and listening for clients. The client connects, sends a test object (just a String) and outputs it to the command line. It works for the first string sent but none after that.
Server (Hivemind.java):
// Open server socket for listening
ServerSocket ss = null;
boolean listening = true;
try {
ss = new ServerSocket(PORT_NUMBER);
} catch (IOException e) {
System.err.println("Cannot start listening on port " + PORT_NUMBER);
e.printStackTrace();
}
// While listening is true, listen for new clients
while (listening) {
Socket socket = ss.accept();
ServerDispatcher dispatcher = new ServerDispatcher(socket);
dispatcher.start();
}
// Close the socket after we are done listening
ss.close();
Server Thread (ServerDispatcher):
public ServerDispatcher(Socket socket) {
super("ServerDispatcher");
this.socket = socket;
}
public void run() {
System.out.println("Client connected");
try {
input = socket.getInputStream();
objInput = new ObjectInputStream(input);
Object obj = null;
try {
obj = (String)objInput.readObject();
} catch (ClassNotFoundException ex) {
Logger.getLogger(ServerDispatcher.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println(obj);
} catch (IOException ex) {
Logger.getLogger(ServerDispatcher.class.getName()).log(Level.SEVERE, null, ex);
}
Connection Class (HivemindConnect.java):
public HivemindConnect(int port) {
this.port = port;
url = "localhost";
}
public HivemindConnect(int port, String url) {
this.port = port;
this.url = url;
}
public void connect() {
try {
socket = new Socket(url, port);
output = socket.getOutputStream();
objOutput = new ObjectOutputStream(output);
} catch (IOException e) {
e.printStackTrace();
}
}
public void close() {
try {
objOutput.close();
output.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void send(Object obj) {
try {
objOutput.writeObject(obj);
objOutput.flush();
} catch (IOException ex) {
Logger.getLogger(HivemindConnect.class.getName()).log(Level.SEVERE, null, ex);
}
}
CustomerTopComponent:
// When the TC is opened connect to the server
#Override
public void componentOpened() {
hivemind = new HivemindConnect(9001);
hivemind.connect();
}
private void btnSendActionPerformed(java.awt.event.ActionEvent evt) {
hivemind.send(txtText.getText());
}
// When the TC is closed close the connection to the server
#Override
public void componentClosed() {
hivemind.close();
}

You need a loop like this:
while(objInput.available()>0){
Object obj = null;
obj = (String)objInput.readObject();
System.out.println(obj);}
Or something similar.