I need help improving this chat server and chat client!

[Cody Long]

Can someone please help me make this server more secure and the chat client looking a little cooler. Also can you show me how to make it where a user types in their names and it shows up next to the text that they sent? right now it just shows what a person wrote, not wich person. thank you.

ChatServer.Java

  
import java.io.*;
import java.net.*;
import java.util.*;


public class ChatServer
{
    ArrayList clientOutputStreams;
    
    public class ClientHandler implements Runnable {
        BufferedReader reader;
        Socket sock;
        
        public ClientHandler(Socket clientSOcket) {
            try {
                sock = clientSOcket;
                InputStreamReader isReader = new InputStreamReader(sock.getInputStream());
                reader = new BufferedReader(isReader);
                
            } catch (Exception ex) { ex.printStackTrace(); }
        }
        
        public void run() {
            String message;
            try {
                while ((message = reader.readLine()) != null) {
                    System.out.println("read " + message);
                    tellEveryone(message);
                }
            } catch (Exception ex) { ex.printStackTrace(); }
        }
    }
    
    public static void main(String[] args) {
        new VerySimpleChatServer().go();
    }
    
    public void go() {
        clientOutputStreams = new ArrayList();
        try {
            ServerSocket serverSock = new ServerSocket(5000);
            while(true) {
                Socket clientSocket = serverSock.accept();
                PrintWriter writer = new PrintWriter(clientSocket.getOutputStream());
                clientOutputStreams.add(writer);
                
                Thread t = new Thread(new ClientHandler(clientSocket));
                t.start();
                System.out.println("got a connection");
            }
        } catch (Exception ex) { ex.printStackTrace(); }
    }
    
    public void tellEveryone(String message) {
        Iterator it = clientOutputStreams.iterator();
        while (it.hasNext()) {
            try {
                PrintWriter writer = (PrintWriter) it.next();
                writer.println(message);
                writer.flush();
            } catch (Exception ex) { ex.printStackTrace(); }
        }
    }
}
  

ChatClient.java

  
import java.io.*;
import java.net.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


public class ChatClient
{
    JTextArea incoming;
    JTextField outgoing;
    BufferedReader reader;
    PrintWriter writer;
    Socket sock;
    
    public void go() {
        JFrame frame = new JFrame("Monkeypwn Chat!");
        JPanel mainPanel = new JPanel();
        incoming = new JTextArea(15, 50);
        incoming.setLineWrap(true);
        incoming.setWrapStyleWord(true);
        incoming.setEditable(false);
        JScrollPane qScroller = new JScrollPane(incoming);
        qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
        qScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
        outgoing = new JTextField(20);
        JButton sendButton = new JButton("Send");
        sendButton.addActionListener(new SendButtonListener());
        mainPanel.add(qScroller);
        mainPanel.add(outgoing);
        mainPanel.add(sendButton);
        frame.getContentPane().add(BorderLayout.CENTER, mainPanel);
        setUpNetworking();
        
        Thread readerThread = new Thread(new IncomingReader());
        readerThread.start();
        
	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(650, 500);
        frame.setVisible(true);
        
    }
    
    private void setUpNetworking() {
        try {
            sock = new Socket("127.0.0.1", 5000);
            InputStreamReader streamReader = new InputStreamReader(sock.getInputStream());
            reader = new BufferedReader(streamReader);
            writer = new PrintWriter(sock.getOutputStream());
            System.out.println("networking established");
        }
        catch(IOException ex)
        {
            ex.printStackTrace();
        }
    }
    
    public class SendButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent ev) {
            try {
                writer.println(outgoing.getText());
                writer.flush();
                
            }
            catch (Exception ex) {
                ex.printStackTrace();
            }
            outgoing.setText("");
            outgoing.requestFocus();
        }
    }
    
    public static void main(String[] args) {
        new SimpleChatClient().go();
    }
    
    class IncomingReader implements Runnable {
        public void run() {
            String message;
            try {
                while ((message = reader.readLine()) != null) {
                    System.out.println("client read " + message);
                    incoming.append(message + "\n");
                }
            } catch (IOException ex)
            {
                ex.printStackTrace();
            }
        }
    }
}


  

[Rob Prime]

The server has to inform the clients on who has sent the message. You can do that by either sending the user name from the client with the message, or by recognizing the user from the specific ClientHandler. I'd say the first solution is the easiest, and it keeps user names local to one place.

As for security, you could add both a welcome message and a departure message. A client first sends the welcome message when connected, and the server rejects the socket if the welcome message does not match. If a client disconnects it can send a departure message that allows your server to nicely clean up its resources (and inform other users that the user has left).

[Cody Long]

Rob Prime wrote:The server has to inform the clients on who has sent the message. You can do that by either sending the user name from the client with the message, or by recognizing the user from the specific ClientHandler. I'd say the first solution is the easiest, and it keeps user names local to one place.

As for security, you could add both a welcome message and a departure message. A client first sends the welcome message when connected, and the server rejects the socket if the welcome message does not match. If a client disconnects it can send a departure message that allows your server to nicely clean up its resources (and inform other users that the user has left).

how would you do that? i am a beginning programmer and got the server code from a friend and i dont know where he got it. the client part i made via the server info but i still can not figure out how to get the username [art and how to add more security.

[Cody Long]

thank you for your help i figured out how to do it in time.

[Henry Wong]

Cody Long wrote:thank you for your help i figured out how to do it in time.

Well, I am sure that once you figure out the code, then Rob suggestions will start to make sense. It is hard to change code when you don't know how it works -- especially for a beginner.

Henry

[Cody Long]

yeah but thankfully newbishness seems to come off pretty quick sometimes!