Solution: Simple Chat Server Chat application can be described as a connection-oriented service because a user establishes a connection and maintains that connection. send and receive text,image and Audio-Video files for the duration of the session. There should not be a confusion from Web Protocol because in web, the browser asks for a page and the server sends it and then connection is closed but in Chat application client need to maintain the connection for the session. Basics of Chat Server:
Server Class which can be started as s standalone application basically you can say Listener.
Mechanism for accepting the connections.
Mechanism for reading and writing data on server side.
Client class which can be started as a standalone application.
A thread class which can creates separate thread for each client.
Mechanism for reading and writing data on client side.
Closing the chat connections.
Server Class(Listener Class) : public class Server { public Server(int port) throws IOException { listen(port); } private void listen(int port) { // will explain in future } } Server Thread: import java.net.Socket; public class ServerThread extends Thread { public ServerThread(Server server,Socket socket) { this.server=server; this.socket=socket; start(); //start the thread } } Client Class Method: public Client(String host,int port) { setLayout(new BorderLayout); add("North",tf); add("Center",ta); tf.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent arg0) { // TODO Auto-generated method stub processMesssage(e.getActionCommand()); } }); } Complete Code Implementation: import java.applet.Applet; import java.awt.BorderLayout; import java.awt.Panel; import java.awt.TextArea; import java.awt.TextField; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.EOFException; import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.net.UnknownHostException; import java.util.Enumeration; import java.util.Hashtable; /** * */ /** * @author Abhinaw.Tripathi * */ class Server { private ServerScocket ss; private Hashtable OutputStreams =new Hashtable<>(); public Server(int port) throws IOException { listen(port); } private void listen(int port) { ss=new ServerSocket(port); System.out.println("Listening on" + ss); while(true) { Socket s=ss.accept(); System.out.println("Connection from " + s); DataOutputStream dout= new DataOutputStream(s.getOutputStream()); OutputStreams.put(s, dout); new ServerThread(this,s); } } Enumeration getOutputStreams() { return OutputStreams.elements(); } void sendToAll(String message) { synchronized (OutputStreams) { for(Enumeration e=getOutputStreams();e.hasMoreElements();) { DataOutputStream DOUT =(DataOutputStream)e.nextElement(); try { DOUT.writeUTF(message); } catch(IOException ie) { System.out.println(ie); } } } } void removeConnection(Socket s) { synchronized (OutputStreams) { System.out.println("Removing connection " + s); OutputStreams.remove(s); try { s.close(); } catch(Exception e) { System.out.println("Error closing " +s); } } } } class ServerThread extends Thread { private Server server; private Socket socket; public ServerThread(Server server,Socket socket) { this.server=server; this.socket=socket; start(); } public void run() { try { DataInputStream din=new DataInputStream(socket.getInputStream()); String message=din.readUTF(); System.out.println("Sending " +message); server.sendToAll(message); } catch(EOFException e) { } catch (IOException e) { } finally { server.removeConnection(socket); } } } class Client extends Panel implements Runnable { private TextField tf=new TextField(); private TextArea ta=new TextArea(); private Socket socket; private DataOutputStream dout; private DataInputStream din; public Client(final String host,final int port) { setLayout(new BorderLayout()); add("North",tf); add("Center",ta); tf.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent arg0) { try { socket =new Socket(host,port); System.out.println("connected to " +socket); din=new DataInputStream(socket.getInputStream()); dout=new DataOutputStream(socket.getOutputStream()); new Thread().start(); } catch (IOException e) { e.printStackTrace(); } } }); } @Override public void run() { while(true) { try { String message=din.readUTF(); ta.append(message + "\n"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } private void processMessage(String message) { try { dout.writeUTF(message); tf.setText(" "); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } class ClientApplet extends Applet { public void init() { String host=getParameter("host"); int port=Integer.parseInt(getParameter("port")); setLayout(new BorderLayout()); add("Center",new Client(host, port)); } } public class SimpleChatServerTest { /** * */ public SimpleChatServerTest() { // TODO Auto-generated constructor stub } /** * @param args */ public static void main(String[] args) { int port=Integer.parseInt(args[0]); try { new Server(port); } catch (IOException e) { e.printStackTrace(); } } }