ChatServerClient.java

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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;

import net.chayden.Eliza.Eliza;

/**
 *  Chat server's threaded back-end for clients.
 *  
 *  @author Mikica B Kocic
 */
public class ChatServerClient extends Thread
{
    /**
     *  Instance of the server to which this client belongs
     */
    private ChatServer  server;
    
    /**
     *  Output stream to remote client
     */
    private PrintWriter out;

    /**
     *  Identifier of the client (remote ip addre + remote port)
     */
    private String clientName;
    
    /**
     *  Connection socket to server
     */
    private Socket socket;
    
    /**
     *  Indicates if thread is (or should be) running
     */
    private volatile boolean running;

    /**
     *  Instance of Joseph Weizenbaum's Eliza, a simulation of a Rogerian shrink.
     *  Eliza may talk to user (if called up) if user is alone in the chat room.
     */
    private Eliza eliza;

    /**
     *  Creates instance of chat server's threaded back-end for specific client
     *  
     *  @param server   instance of the chat server, i.e. owner of this back-end
     *  @param socket   socket to remote chat client accepted by the server earlier
     */
    public ChatServerClient( ChatServer server, Socket socket )
    {
        this.server     = server;
        this.socket     = socket;
        this.out        = null;
        this.running    = true;
        this.eliza      = null;

        /* Setup initial client name as <addr>:<port>.
         * It will be resolved later in <hostname>:<port>, when the thread starts.
         */
        this.clientName = socket.getInetAddress ().getHostAddress () 
                        + ":" + socket.getPort ();
    }

    /**
     *  Gets identifier of the client
     */
    public String getClientName ()
    {
        return clientName;
    }
    
    /**
     *  Sends message (appended with new-line) to chat server
     *  
     *  @param message
     */
    public void send( String message )
    {
        synchronized( this )
        {
            if ( out == null || message == null ) {
                return;
            }
            
            out.println( message );
            out.flush ();
        }
    }

    /**
     *  Sends messages from Eliza
     */
    private void sendFromEliza( String messageFromEliza )
    {
        server.logEliza( messageFromEliza, this );
        send( "Eliza :: " + messageFromEliza );
    }
    
    /**
     *  Broadcasts message, talks to Eliza, responds to "wwhhoo" command etc.
     */
    private void respondToMessage( String message )
    {
        /* Parse input with syntax: [ [ <userId> ] ":: " ] <message>
         * where default userId is [Anonymous].
         */
        String textPart = message;
        String[] parts = message.split( ":: ", 2 );
        // String userId = "[Anonymous]";
        
        if ( parts.length == 0 ) {
            textPart = parts[0];
        } else if ( parts[0].trim().length () == 0 && parts.length >= 2 ) {
            textPart = parts[1];
        } else if ( parts.length >= 2 ) {
            // userId  = parts[0].trim();
            textPart = parts[1];
        } else {
            textPart = parts[0];
        }

        if ( textPart.equals( "wwhhoo" ) ) 
        {
            server.wwhhoo( this );
        }
        else if ( server.getClientCount () == 1 && eliza != null )
        {
            server.broadcast( this, message );
            sendFromEliza( eliza.processInput( textPart ) );
        }
        else if ( eliza == null && textPart.equalsIgnoreCase( "talk eliza" ) ) 
        {
            server.broadcast( this, message );
            if ( server.getClientCount () > 1 )
            {
                sendFromEliza( "We are not alone!" );
            }
            else
            {
                eliza = new Eliza( /*local=*/true, "eliza-script.txt" );
                sendFromEliza( "Hello! My name is Eliza and I am the psychoterapist. " );
                sendFromEliza( " It seems that we are alone... "
                               + "Please tell me your problem." );
            }
        }
        else
        {
            server.broadcast( this, message );
        }
    }

    /**
     * 
     */
    @Override
    public void run ()
    {
        // Create i/o buffers on client socket
        //
        BufferedReader in = null;
        try
        {
            this.clientName = socket.getInetAddress ().getHostName () 
                + ":" + socket.getPort ();

            in = new BufferedReader(
                    new InputStreamReader( socket.getInputStream (), "utf-8" ) );

            out = new PrintWriter(
                    new OutputStreamWriter( socket.getOutputStream(), "utf-8" ),
                    /*autoflush*/ true );

            // Live and well if reached following line
            //
            server.broadcast( null, "New client [" + getClientName() + "]" );
            
            if ( server.getClientCount() == 1 && eliza == null )
            {
                send( "[System] :: It seems that you are alone in the chat room. "
                        + "Reply with 'talk eliza' if you want to bring up Eliza..." );
            }
        }
        catch (IOException ex)
        {
            running = false;
        }

        while( running )
        {
            try
            {
                String message = in.readLine ();
                if ( message == null ) {
                    running = false;
                    break;
                }

                respondToMessage( message );
            }
            catch( IOException ex )
            {
                running = false;
            }
        }

        // On socket error or regular disconnect
        //
        server.removeClient( this );
        server.broadcast( null, "Client [" + getClientName() + "] disconnected" );
    }

}