I develop code to send form client to server then the server has to send what it receives from client again to client. but in my code the server only receives the message but does not resend it again. I do not know what is the problem
This is my client code
public class Client implements Runnable{
private static Socket s = null;
//private static BufferedOutputStream fromUser = null;
private static DataInputStream fromServer = null;
private static InputStreamReader input = new InputStreamReader(System.in);
private static InputStreamReader inputstreamreader = null;
private static BufferedReader bufferedreader = null;
private static DataOutputStream fromUser = null;
private static int chara = 0;
private static String line = null;
static int port = 0;
static String host = null;
//connect to server
#Override
public void run() {
try {
inputstreamreader = new InputStreamReader(s.getInputStream());
bufferedreader = new BufferedReader(inputstreamreader);
//charr = fromClient.read();
while(true){
if ((line = bufferedreader.readLine()) != null){
System.out.println(line);}
if(line.equals(-1)){
break;
}
}//end while
}catch(NullPointerException e) {
// do something other
}
catch (IOException e) {
System.out.println(e);
}
}//end the run
//constructor with two arguments
public Client(String host, int port){
try{
s = new Socket (host,port);
}
catch(Exception e){}
}
//send message to from Client to Server
public static void sendToServer(){
try{
fromUser =new DataOutputStream (new BufferedOutputStream(s.getOutputStream()));
chara =input.read();
while(true){
if (chara == '~'){
break;}
fromUser.write(chara);
fromUser.flush();
chara =input.read();
}//end while
}
catch (IOException e) {
System.out.println(e);
}
}//end send message
I tried to use thread to receive message but also does not work. I tried without thread it does not work too.
public static void main(String [] args){
host = args[0];
port = Integer.parseInt(args[1]);
System.out.println("Start connection .....");
Client client = new Client(host,port);
Thread thread = new Thread(client);
thread.start();
//connect(host,port);
client.sendToServer();
client.close();
}//end main
and this is my server code
public class Server extends Thread{
private static Socket s = null;
private static ServerSocket ss = null;
private static DataOutputStream fromUser = null;
private static DataInputStream fromClient = null;
private static InputStreamReader input = new InputStreamReader(System.in);
private static InputStreamReader inputstreamreader = null;
private static BufferedReader bufferedreader = null;
static String line=null;
static String sendC;
private static int chara = 0;
static int port = 0;
//connect to server
static void connect(int port){
try{
ss = new ServerSocket (port);
System.out.println("Listening on port "+port+"...");
s = ss.accept();
System.out.println("Has been connected .....");
}
catch (IOException e) {
System.out.println(e);
}
}//end of the connection method
//send message to from Client to Server
public static void sendToClient(String text){
try{
fromUser =new DataOutputStream (new BufferedOutputStream(s.getOutputStream()));
sendC =text;
fromUser.write(sendC.getBytes());
fromUser.flush();
}
catch (IOException e) {
System.out.println(e);
}
}//end send message
public static void receiveFromClient(){
try {
inputstreamreader = new InputStreamReader(s.getInputStream());
bufferedreader = new BufferedReader(inputstreamreader);
//charr = fromClient.read();
while(true){
if ((line = bufferedreader.readLine()) != null){
System.out.println(line);
sendToClient(line);}
if(line.equals(-1)){
break;
}
}//end while
}catch(NullPointerException e) {
// do something other
}
catch (IOException e) {
System.out.println(e);
}
}//end send message
this is main method for server
public static void main(String [] args){
port = Integer.parseInt(args[0]);
System.out.println("Start connection .....");
connect(port);
receiveFromClient();
//sendToClient();
close();
}//end main
I do not have alot of knowledge in java especially about the socket
thanks for your help
a simply search for a java echo server shows this
public class EchoServer {
public static void main(String[] args) throws Exception {
// create socket
int port = 4444;
ServerSocket serverSocket = new ServerSocket(port);
System.err.println("Started server on port " + port);
// repeatedly wait for connections, and process
while (true) {
// a "blocking" call which waits until a connection is requested
Socket clientSocket = serverSocket.accept();
System.err.println("Accepted connection from client");
// open up IO streams
In in = new In (clientSocket);
Out out = new Out(clientSocket);
// waits for data and reads it in until connection dies
// readLine() blocks until the server receives a new line from client
String s;
while ((s = in.readLine()) != null) {
out.println(s);
}
// close IO streams, then socket
System.err.println("Closing connection with client");
out.close();
in.close();
clientSocket.close();
}
}
}
see http://introcs.cs.princeton.edu/java/84network/EchoServer.java.html
Related
my server class
import java.net.*;
import java.io.*;
public class server
{
private Socket socket;
private ServerSocket server;
// constructor with port
public void start(int port){
try {
server = new ServerSocket(port);
while(true){
socket = server.accept();
new ConnectionHandler(socket).run();
}
}catch(IOException i){
}
}
}
class ConnectionHandler implements Runnable{
private Socket socket = null;
private ServerSocket server = null;
private DataInputStream in = null;
public ConnectionHandler(Socket socket){
this.socket=socket;
}
#Override
public void run() {
InputStream inp = null;
BufferedReader brinp = null;
DataOutputStream out = null;
try
{
System.out.println("Waiting for a client ...");
System.out.println(server);
System.out.println("Client accepted");
in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
String line = "";
// reads message from client until "Over" is sent
while (!line.equals("Over"))
{
try
{
line = in.readUTF();
System.out.println(line);
}
catch(IOException i)
{
System.out.println(i);
}
}
System.out.println("Closing connection");
// close connection
socket.close();
in.close();
}
catch(IOException i)
{
System.out.println(i);
}
}
public static void main(String[] args) {
server serverr = new server();
serverr.start(4000);
}
}
Here's my client class.
import java.net.*;
import java.io.*;
public class Client
{
// initialize socket and input output streams
private Socket socket = null;
private DataInputStream input = null;
private DataOutputStream out = null;
// constructor to put ip address and port
public Client(String address, int port)
{
// establish a connection
try
{
socket = new Socket(address, port);
System.out.println("Connected");
// takes input from terminal
input = new DataInputStream(System.in);
// sends output to the socket
out = new DataOutputStream(socket.getOutputStream());
}
catch(UnknownHostException u)
{
System.out.println(u);
}
catch(IOException i)
{
System.out.println(i);
}
// string to read message from input
String line = "";
// keep reading until "Over" is input
while (!line.equals("Over"))
{
try
{
line = input.readLine();
out.writeUTF(line);
}
catch(IOException i)
{
System.out.println(i);
}
}
// close the connection
try
{
input.close();
out.close();
socket.close();
}
catch(IOException i)
{
System.out.println(i);
}
}
public static void main(String args[])
{
Client client = new Client("127.0.0.1", 4000);
}
}
Trying to develop pretty simple chat application works via terminal, but I think there are plenty of bugs I have in my code.
The server can handle one client, but when another client comes up it doesn't connect to other clients.
What am I have to do now?
I couldn't find out where my problem is, waiting your helps.
Note: I am completely new to socket programming concept.
The ConnectionHandler class is a thread class, and you must wrap its object to a Thread instance and then call start() instead of run().
So in the Server class change
new ConnectionHandler(socket).run();
with
new Thread(ConnectionHandler(socket)).start();
I am creating a simple Java program where the client sends a message to the server and the server replies back with a confirmation message. But my question is: Can I get the server response/broadcast before the BufferedReader line?
Server:
public class Multithread extends Thread{
Socket sock;
static ArrayList<Multithread> clientList = new ArrayList<Multithread>();
public Multithread(Socket sock){
this.sock = sock;
}
public void run(){
try{
DataInputStream in = new DataInputStream(this.sock.getInputStream());
String read = in.readUTF();
if(read.equalsIgnoreCase("exit")){
System.out.println(this.sock.getRemoteSocketAddress()+" just dced");
clientList.remove(this);
this.sock.close();
}
else{
String said = this.sock.getRemoteSocketAddress() +" said "+read;
System.out.println(said);
for(Multithread multi : clientList){
DataOutputStream o = new DataOutputStream(multi.sock.getOutputStream());
o.writeUTF(said);
}
this.sock.close();}
}catch(IOException e){
}
}
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = new ServerSocket(7777);
System.out.println("Listening");
while(true){
Socket socket = serverSocket.accept();
System.out.println("Connected to "+socket.getRemoteSocketAddress());
Multithread multi = new Multithread(socket);
clientList.add(multi);
multi.start();
}
}
}
Client:
public class Clients{
public static void main(String[] args) throws UnknownHostException, IOException {
while(true){
Socket socket = new Socket("localhost",7777);
DataInputStream in = new DataInputStream(socket.getInputStream());
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String line = br.readLine();
out.writeUTF(line);
if(line.equalsIgnoreCase("exit"))
{
System.out.println("Disconnected");
socket.close();
break;
}
else{
System.out.println("Server said :"+in.readUTF());
socket.close();
}
}
}
}
I would like to know, how to send messages to all connected clients. To be more specific - to all ServerThreads.
Here are my classes:
public class Client {
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException {
Socket kkSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try {
kkSocket = new Socket("127.0.0.1", 4444);
out = new PrintWriter(kkSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream()));
} catch (UnknownHostException e) {
System.err.println("Don't know about host: localhost.");
System.exit(1);
} catch (IOException e) {
System.err.println("Couldn't get I/O for the connection to: localhost.");
System.exit(1);
}
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
String fromUser, fromServer;
while (!(fromUser = stdIn.readLine()).equalsIgnoreCase("#quit")) {
out.println(fromUser);
fromServer = in.readLine();
System.out.println(fromServer);
}
out.close();
in.close();
stdIn.close();
kkSocket.close();
}
}
Server: http://pastebin.com/ZpBydK58
ServerThread: http://pastebin.com/CwAM72c3
Assign each new ServerThread to a array. Then you can make a method in Server that loops through the ServerThread array and sends a message to each, and in ServerThread make a method to send a message.
Example:
public class Server {
public final static int maxClients = 10000;
public final static ServerThread[] clients = new ServerThread[maxClients];
public static int numOfClients = 0;
public static ServerSocket server;
public static void main(String[] args){
try{
server = new ServerSocket(4444);
while (numOfClients<maxClients){
clients[numOfClients+1] = new ServerThread(server.accept());
numOfClients++;
clients[numOfClients].start();
}
while (true){
server.accept().close();
}
}catch(Exception error){error.printStackTrace();}
}
public static void sendMessage(String message){
for (int i=0;i<numOfClients;i++){
clients[i].sendMessage(message);
}
}
}
I have some (incomplete) code here for a client/server pair, here is the server class, but for some reason unknown to me the code appears to stop running anything below the serverSocket.accept()
What am I doing wrong?
Thanks
class MPTagServer{
public String serverName = "MPTag Server";
public int gSize = 16;
public int maxPlayers = 16;
ServerSocket serverSocket = null;
Socket clientSocket = null;
PrintWriter out = null;
BufferedReader in = null;
MPTagServer(String sn, int gs, int mp){
serverName = sn;
gSize = gs;
maxPlayers = mp;
}
public void start() throws Exception{
Task serverTask = new Task<Void>(){
#Override protected Void call() throws Exception{
int port = 6789;
try{
serverSocket = new ServerSocket(port);
}
catch(IOException e){
System.err.println("Could not listen on port: " + port);
System.exit(1);
}
try{
System.out.println("This will print");
clientSocket = serverSocket.accept(); //Code won't run below here
System.out.println("This won't print");
}
catch(IOException e){
System.err.println("Accept failed.");
System.exit(1);
}
out = new PrintWriter(clientSocket.getOutputStream(), true);
in = new BufferedReader(
new InputStreamReader(clientSocket.getInputStream()));
String inputLine, outputLine;
ComProtocol cp = new ComProtocol();
outputLine = cp.init();
out.println(outputLine);
out.close();
in.close();
clientSocket.close();
serverSocket.close();
return null;
}
};
Thread serverThread = new Thread(serverTask);
serverThread.setDaemon(true);
serverThread.start();
}
}
ServerSocket.accept() blocks until a connection is made to the socket. See http://docs.oracle.com/javase/6/docs/api/java/net/ServerSocket.html#accept(). When a client connects to your socket, the socket will unblock, and you should see "This won't print".
Hello, I am new to java socket programming and I was just looking to see if somebody could give me some help.
I will post the code for the client and server then i will explain my problem...
reader = new BufferedReader(new InputStreamReader(socket.getInputStream));
while(running)
{
String line = reader.readLine();
if(line != null)
{
System.out.println(line);
stream = new PrintStream(socket.getOutputStream());
stream.println("return: " + line);
}
}
}catch(IOException e)
{
System.out.println("Socket in use or not available: " + port);
}
}
public static void main()
{
run();
}
//Client
public static String ip;
public static int port;
public static Socket socket;
public static PrintStream stream;
public static BufferedReader reader;
public static void main(String args[])
{
try
{
socket = new socket(ip, port);
stream = new PrintStream(socket.getOutputStream());
stream.println("test0");
reader = new BufferedReader(new InputStreamReader(socket.getInputStream));
String line = reader.readLine();
if(line != null)
{
System.out.println(line);
}
stream.println("test1");
line = reader.readLine();
if(line != null)
{
System.out.println(line);
}
}catch(IOException e)
{
System.out.println("could not connect to server!");
}
}
So my problem is even if I get rid of the loop and try to make it send the string twice it won't send it. It will only do it once unless I close and make a new socket on the client side. So if anybody could give me an explanation to what I am doing wrong that would be great, and thank you so much.
Why are you openning your outstream inside your loop?
stream = new PrintStream(socket.getOutputStream());
Take this statement outside the loop and write to your stream inside your loop.
Please keep it simple,
Try using InputStream, InputStreamReader, BufferedReader, OutputStream, PrintWriter.
Client Side:
Socket s = new Socket();
s.connect(new InetSocketAddress("Server_IP",Port_no),TimeOut);
// Let Timeout be 5000
Server Side:
ServerSocket ss = new ServerSocket(Port_no);
Socket incoming = ss.accept();
For Reading from the Socket:
InputStream is = s.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
boolean isDone = false;
String s = new String();
while(!isDone && ((s=br.readLine())!=null)){
System.out.println(s); // Printing on Console
}
For Writing to the Socket:
OutputStream os = s.getOuptStream();
PrintWriter pw = new PrintWriter(os)
pw.println("Hello");
Make sure you flush the output from your server:
stream.flush();
Thanks a lot to everybody who answered but i figures out what it was all along.
i read through some of the Oracle socket stuff and figured out that the server was supposed to be the first to send a message than the client receive and send and receive... so on and so forth so i will post my new code here in hopes somebody else trying to figure out the same thing can find it with ease
//Client
public static String ip;
public static int port;
public static Socket socket;
public static PrintWriter print;
public static BufferedReader reader;
public Client(String ip, int port)
{
this.ip = ip;
this.port = port;
//initiate all of objects
try
{
socket = new Socket();
socket.connect(new InetSocketAddress(ip, port), 5000);
print = new PrintWriter(socket.getOutputStream());
reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//start connection with server
String line = reader.readLine();
System.out.println(line);
} catch (IOException e)
{
e.printStackTrace();
}
}
//quick method to send message
public void sendMessage(String text)
{
print.println(text);
print.flush();
try
{
String line = reader.readLine();
System.out.println(line);
} catch (IOException e)
{
e.printStackTrace();
}
}
}
public static void main(String args[])
{
client.sendMessage("test");
client.sendMessage("test2");
client.sendMessage("test3")
}
//Server
public static int port = 9884;
public static boolean running = true;
public static ServerSocket serverSocket;
public static Socket socket;
public static PrintWriter writer;
public static BufferedReader reader;
public static void run()
{
try
{
serverSocket = new ServerSocket(port);
socket = serverSocket.accept();
writer = new PrintWriter(socket.getOutputStream(), true);
writer.println("connection");
while(running)
{
reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String line = reader.readLine();
if(line != null)
{
System.out.println(line);
writer.println(line);
writer.flush();
}
}
} catch (IOException e)
{
e.printStackTrace();
}
}
public static void main(String args[])
{
run();
}