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Client and Echo server connected but not client not sending the message to server

A client connects successfully to the server and gets the message "Echo server started.." from the server but when writing to the server nothing happens. Im trying to create an Echo Client program that will connect to the Echo Server (which I assume is successful) now what's left is the communication between the client and the echo server. Any help with to point out the flaw will be appreciated!
Client:
import java.net.*;
import java.util.*;
import java.io.*;
public class GreetinEchoClient {
public static void main(String [] args) throws IOException
{
System.out.println("Echo client ...");
InetAddress localHost = InetAddress.getLocalHost();
Socket socket = new Socket(localHost, 7777);
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
System.out.println("We are connected to echo server");
Scanner scanner = new Scanner(System.in);
while(true) {
System.out.println("Enter message :");
String input = scanner.nextLine();
if("exit".equalsIgnoreCase(input)) {
break;
}
out.println(input);
String response = br.readLine();
System.out.println("Server response :" + response);
} try {
socket.close();
scanner.close();
}catch (IOException e) {}
}
Echo server:
import java.io.*;
import java.net.*;
public class GreetinEcho {
public static void main(String [] args) {
ServerSocket echoServer = null;
String line;
DataInputStream is;
DataOutputStream os;
Socket clientSocket = null;
try {
echoServer = new ServerSocket(7777);
System.out.println("Echo Server Started....");
}
catch (IOException e) {
System.out.println(e);
}
try {
clientSocket = echoServer.accept();
System.out.println("Connected to the client " + clientSocket.getRemoteSocketAddress());
is = new DataInputStream(clientSocket.getInputStream());
os = new DataOutputStream(clientSocket.getOutputStream());
while(true) {
line = is.readUTF();
System.out.println("On Server :" + line);
os.writeUTF(line);
}
} catch (IOException e) {
System.out.println(e);
}
}
}

Handle more clients

Right now my server only can handle one client at a time. I am trying to use a Thread so that the server can handle several clients, but I am doing it wrong. I have added the thread in the try/catch clause where the serverSocket accepts the client, but this makes no difference. I don't get an error or anything, but it just doesn't work.
So what I want to do, is make the server not freeze at one client, but still accept several clients.
Here is the server code:
import java.io.*;
import java.net.*;
public class Server {
private BufferedReader reader;
private PrintWriter writer;
private int port;
public Server(int port)
{
this.port = port;
}
private String getSeverAddress() {
String host = null;
try {
InetAddress adr = InetAddress.getLocalHost();
host = adr.getHostAddress();
} catch (UnknownHostException e) {
e.printStackTrace();
}
return host;
}
public void startServer() {
print("Contact this sever on address: " + getSeverAddress() + " port: " + port);
ServerSocket ss = null;
Socket socket = null;
Thread clientThread = null;
try {
ss = new ServerSocket(port);
socket = ss.accept();
clientThread = new Thread(new Client(socket));
clientThread.start();
reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
writer = new PrintWriter(socket.getOutputStream(), true);
String msg = null;
while (( msg = reader.readLine()) != null) {
print("System out: " + msg);
if(msg.equals("Bye")) {
print("Client left");
break;
}
}
ss.close();
socket.close();
reader.close();
writer.close();
} catch(SocketException e) {
e.printStackTrace();
} catch (IOException i ) {
i.printStackTrace();
return;
}
}
private void print(String msg) {
System.out.println(msg);
}
public static void main(String[] args) {
Server server = new Server(1111);
server.startServer();
}
}
Here is the client code:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
public class Client implements Runnable{
private Socket client;
private BufferedReader reader;
private PrintWriter writer;
public Client(Socket socket)
{
client = socket;
try{
reader = new BufferedReader(new InputStreamReader(client.getInputStream()));
writer = new PrintWriter(client.getOutputStream(), true);
} catch (Exception e) {
e.printStackTrace();
return;
}
}
#Override
public void run() {
String msg = null;
BufferedReader r = null;
try {
r = new BufferedReader(new InputStreamReader(System.in));
} catch (Exception e1) {
e1.printStackTrace();
}
System.out.println("Write message to server");
while(true) {
try {
msg = r.readLine();
if(msg.equals("Quit") || msg == null) {
print("Disconnect");
break;
}
} catch (IOException e) {
e.printStackTrace();
}
writeToServer(msg);
}
try {
r.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void writeToServer(String msg) {
writer.println(msg);
}
private void print(String msg) {
System.out.println(msg);
}
public static void main(String[] args) {
Socket socket = null;
try {
socket = new Socket("localhost", 1111);
} catch (Exception e) {
e.printStackTrace();
}
Client client = new Client(socket);
client.run();
}
}

You are still trying to handle clients in your main thread. Main thread should just accept new connections and start new threads. You also have to do accept in a loop so multiple connections can be accepted:
ss = new ServerSocket(port);
while(true) {
Socket socket = ss.accept();
Thread clientThread = new Thread(new Runnable() {
public void run() {
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);
String msg = null;
while (( msg = reader.readLine()) != null) {
print("System out: " + msg);
if(msg.equals("Bye")) {
print("Client left");
break;
}
}
socket.close();
reader.close();
writer.close();
}});
clientThread.start();
}

You need to put your ss.accept() into a while loop and create a new Thread for every client accepted, which handles the connection.

BufferedReader from server does not work

In this code I can correctly receive a request using BufferedReader inClient, created on the client socket.
Then I send the request to the server and I see the server gets it.
But then, when I try to read the reply from the server (using BufferedReader inServer on the socket of the server), it always ends in IOException: Impossible read from server.
I am referring to the block ################
Do you know any possible reasons?
import java.io.*;
import java.net.Socket;
import java.net.ServerSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;
public class ProxyMain {
public static void main(String argv[]) {
int proxyPort = 55554;
String proxyAddr = "127.0.0.1";
ServerSocket proxySocket = null;
try {
proxySocket = new ServerSocket(proxyPort, 50, InetAddress.getByName("127.0.0.1"));
}
catch (Exception e) {
System.err.println("Impossible to create socket server!");
System.out.flush();
System.exit(1);
}
System.out.printf("Proxy active on port: %d and on address %s\n", proxyPort, proxySocket.getInetAddress());
System.out.println();
while (true) {
Socket client = null;
Socket sockServ = null;
BufferedReader inClient = null;
PrintWriter outClient = null;
BufferedReader inServer = null;
PrintWriter outServer = null;
String request = new String();
String tmp = new String();
String reply = new String();
String tmpReply = new String();
try {
client = proxySocket.accept();
System.out.println("Connected to: ");
System.out.println(client.getInetAddress().toString());
System.out.printf("On port %d\n", client.getPort());
System.out.println();
inClient = new BufferedReader(new InputStreamReader(client.getInputStream()));
outClient = new PrintWriter(client.getOutputStream(), true);
}
/*catch (IOException e) {
System.err.println("Couldn't get I/O for connection accepted");
System.exit(1);
}*/
catch (Exception e) {
System.out.println("Error occurred!");
System.exit(1);
}
System.out.println("Received request:");
try{
for (int i = 0; i<2; i++) {
tmp = inClient.readLine();
request = request + tmp;
}
inClient.close();
}
catch (IOException ioe) {
System.err.println("Impossible to read mhttp request!");
System.exit(1);
}
System.out.println(request);
System.out.println();
try {
sockServ = new Socket("127.0.0.1", 55555);
outServer = new PrintWriter(sockServ.getOutputStream(), true);
inServer = new BufferedReader(new InputStreamReader(sockServ.getInputStream()));
}
catch (UnknownHostException e) {
System.err.println("Don't know about host: 127.0.0.1:55555");
System.exit(1);
}
catch (IOException e) {
System.err.println("Couldn't get I/O for the connection to: 127.0.0.1:55555");
System.exit(1);
}
outServer.println(request);
outServer.close();
try {
#################################################
while ((tmpReply = inServer.readLine()) != null) {
System.out.println(tmpReply);
reply = reply + tmpReply;
}
inServer.close();
sockServ.close();
}
catch (IOException ioe) {
System.err.println("Impossible to read from server!");
System.exit(1);
}
outClient.println(reply);
outClient.close();
try {
client.close();
}
catch (IOException ioe) {
System.err.printf("Impossible to close connection with %s:%d\n", client.getInetAddress().toString(), client.getPort());
}
}
}
}
UPDATE:
It seems that if I do:
boolean res = inServer.ready();
it always return false.
So Server is not ready to send the reply but this is strange...with my Project in C e Python it worked immediately. Why should java be different?

When you close outServer, you close the underlying socket. if you just want to close the output and keep the input open, you need to use Socket.shutdownOutput(). note, you have the same problem when you close inClient.

This works, maybe you can get some ideas from it...
ChatServer - broadcasts to all connected clients
In one command prompt: java ChartServer
In another: java ChatClient localhost (or the ip address of where the server is running)
And another: java ChatClient localhost (or the ip address of where the server is running)
Start chatting in the client windows.
Server like this...
// xagyg wrote this, but you can copy it
import java.io.*;
import java.net.*;
import java.util.*;
public class ChatServer {
public static List list = new ArrayList();
public static void main(String[] args) throws Exception {
ServerSocket svr = new ServerSocket(4444);
System.out.println("Chat Server started!");
while (true) {
try {
Socket s = svr.accept();
synchronized(list) {
list.add(s);
}
new Handler(s, list).start();
}
catch (IOException e) {
// print out the error, but continue!
System.err.println(e);
}
}
}
}
class Handler extends Thread {
private Socket s;
private String ipaddress;
private List list;
Handler (Socket s, List list) throws Exception {
this.s = s;
ipaddress = s.getInetAddress().toString();
this.list = list;
}
public void run () {
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(s.getInputStream()));
String message;
//MyDialog x = (MyDialog)map.get(ipaddress.substring(1));
while ((message = reader.readLine()) != null) {
if (message.equals("quit")) {
synchronized(list) {
list.remove(s);
}
break;
}
synchronized(list) {
for (Object object: list) {
Socket socket = (Socket)object;
if (socket==s) continue;
PrintWriter writer = new PrintWriter(socket.getOutputStream());
writer.println(ipaddress + ": " + message);
writer.flush();
}
}
}
try { reader.close(); } catch (Exception e) {}
}
catch (Exception e) {
System.err.println(e);
}
}
}
Client like this ...
// xagyg wrote this, but you can copy it
import java.util.*;
import java.io.*;
import java.net.*;
public class ChatClient {
public static void main(String[] args) throws Exception {
Socket s = new Socket(args[0], 4444);
BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
PrintWriter out = new PrintWriter(s.getOutputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String message;
new SocketReader(in).start();
while ((message = reader.readLine())!=null) {
out.println(message);
out.flush();
if (message.equals("quit")) break;
}
in.close();
out.close();
}
}
class SocketReader extends Thread {
BufferedReader in;
public SocketReader(BufferedReader in) {
this.in = in;
}
public void run() {
String message;
try {
while ((message = in.readLine())!=null) {
System.out.println(message);
}
}
catch (Exception e) {
throw new RuntimeException(e);
}
}
}

Console based login application using java sockets

I am making a console based java application - which will check the username and password of client. What I want is the data entered by client must enter to server in a line by line format i.e pressing enter must send username data and password for next enter press. But what the problem is - until I quit at the client side the data is not sent to the server. Meaning , when client hits 'Bye.' then the client is closed and server receives the data then. Help me in this regard as this is the first step - later I have to check database with this username and password on server. My codes are as follows :
Server :
import java.net.*;
import java.io.*;
public class EchoServer2 extends Thread
{
protected Socket clientSocket;
public static void main(String[] args) throws IOException
{
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(2010);
System.out.println ("Connection Socket Created");
try {
while (true)
{
System.out.println ("Waiting for Connection");
new EchoServer2 (serverSocket.accept());
}
}
catch (IOException e)
{
System.err.println("Accept failed.");
System.exit(1);
}
}
catch (IOException e)
{
System.err.println("Could not listen on port.");
System.exit(1);
}
finally
{
try {
serverSocket.close();
}
catch (IOException e)
{
System.err.println("Could not close port.");
System.exit(1);
}
}
}
private EchoServer2 (Socket clientSoc)
{
clientSocket = clientSoc;
start();
}
public void run()
{
System.out.println ("New Communication Thread Started");
try {
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),
true);
PrintWriter out1 = new PrintWriter(clientSocket.getOutputStream(),
true);
BufferedReader in = new BufferedReader(
new InputStreamReader( clientSocket.getInputStream()));
BufferedReader in1 = new BufferedReader(
new InputStreamReader( clientSocket.getInputStream()));
String inputLine,u,p;
while ((u = in.readLine()) != null && (p = in.readLine()) != null)
{
System.out.println ("U: " + u);
out1.println(u);
System.out.println ("P: " + p);
out1.println(p);
if (u.equals("Bye."))
break;
}
out1.close();
out.close();
//in1.close();
in.close();
clientSocket.close();
}
catch (IOException e)
{
System.err.println("Problem with Communication Server");
System.exit(1);
}
}
}
Client :
import java.io.*;
import java.net.*;
import java.lang.*;
import java.io.Console;
public class EchoClient2 {
public static void main(String[] args) throws IOException {
String serverHostname = new String ("127.0.0.1");
if (args.length > 0)
serverHostname = args[0];
System.out.println ("Attemping to connect to host " +
serverHostname + " on port .");
Socket echoSocket = null;
PrintWriter out = null;
BufferedReader in = null;
BufferedReader in1 = null;
try {
echoSocket = new Socket(serverHostname, 2010);
out = new PrintWriter(echoSocket.getOutputStream(), true);
in = new BufferedReader(new InputStreamReader(
echoSocket.getInputStream()));
} catch (UnknownHostException e) {
System.err.println("Don't know about host: " + serverHostname);
System.exit(1);
} catch (IOException e) {
System.err.println("Couldn't get I/O for "
+ "the connection to: " + serverHostname);
System.exit(1);
}
BufferedReader stdIn = new BufferedReader(
new InputStreamReader(System.in));
BufferedReader std = new BufferedReader(
new InputStreamReader(System.in));
String upwd,uname,text;
Console console = System.console();
String username = console.readLine("Username:");
char[] pwd = console.readPassword("Password:");
upwd=new String(pwd);
while (username!=null && upwd!=null && (uname = stdIn.readLine()) != null)
{
out.println("Username:"+username);
out.println("Password:"+upwd);
// end loop
if (uname.equals("Bye."))
break;
}
out.close();
stdIn.close();
echoSocket.close();
}
}

On the client side, do out.flush() after writing the password to the stream.

How can I transfer files from Server-Side to Client using Sockets?

I'm having trouble on where to begin performing this task, I'd like some examples or input on how I should set up my server/client components to receive and send data including letting the client download images.
Here's my client-side code:
package V3;
import java.io.*;
import java.net.*;
public class Version3Client {
public static void main(String[] args) throws IOException {
Socket kkSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try {
kkSocket = new Socket("localhost", 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: taranis.");
System.exit(1);
} catch (IOException e) {
System.err.println("Couldn't get I/O for the connection to: taranis.");
System.exit(1);
}
BufferedReader 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();
kkSocket.close();
}
}
And here's my server-side code:
package V3;
import java.net.*;
import java.io.*;
public class Version3Server {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
boolean listening = true;
try {
serverSocket = new ServerSocket(4444);
} catch (IOException e) {
System.err.println("Could not listen on port: 4444.");
System.exit(-1);
}
while (listening)
new Version3ServerThread(serverSocket.accept()).start();
serverSocket.close();
Socket clientSocket = null;
try {
clientSocket = serverSocket.accept();
} catch (IOException e) {
System.err.println("Accept failed.");
System.exit(1);
}
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(
clientSocket.getInputStream()));
String inputLine, outputLine;
Version3Protocol kkp = new Version3Protocol();
outputLine = kkp.processInput(null);
out.println(outputLine);
while ((inputLine = in.readLine()) != null) {
outputLine = kkp.processInput(inputLine);
out.println(outputLine);
if (outputLine.equals("Bye."))
break;
}
out.close();
in.close();
clientSocket.close();
serverSocket.close();
}
}
Thread class added for further specification:
package V3;
import java.net.*;
import java.io.*;
import java.io.FileWriter;
public class Version3ServerThread extends Thread {
private Socket socket = null;
public Version3ServerThread(Socket socket) {
super("Version3ServerThread");
this.socket = socket;
}
public void run() {
try {
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(
socket.getInputStream()));
String inputLine, outputLine;
Version3Protocol kkp = new Version3Protocol();
outputLine = kkp.processInput(null);
out.println(outputLine);
while ((inputLine = in.readLine()) != null) {
outputLine = kkp.processInput(inputLine);
out.println(outputLine);
if (outputLine.equals("Bye"))
break;
if(kkp.getInteraction()){
Logging.writeToFile(socket.getInetAddress());
}
}
out.close();
in.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

The code so far, the client-server-communication without the file-transfer ability, looks fine to me. I wanted to compile to find any errors but you didnt include Version3Protocol and Logging. If it does compile then your next step would be to open the file you want to transfer on the server with a FileInputStream and a new file for writing on the client with FileOutputStream:
http://download.oracle.com/javase/1.4.2/docs/api/java/io/FileInputStream.html
http://download.oracle.com/javase/1.4.2/docs/api/java/io/FileOutputStream.html
You can then read the file into buffer, transfer it using the socket, receive it on the client-side, and copy the buffer-contents into the FileOutputStream there.