Internet News 1999 February/InternetNews_1999_02.iso/pc/Professionale/codici9810/SampleClient.java

Text File | 1998-01-25 | 5KB | 184 lines

/*
**    Programma:        SampleClient
**    Versione:        1.0.0
**    Autore:        Dario de Judicibus
**    Indirizzo:        [e-mail]
**    Creato il:        January 3rd, 1998
**    Modificato il:    January 4th, 1998
**    Linguaggio:        Java (jdk 1.1)
**    -------------------------------------------------------------
**    (c) 1998 - All rights reserved
**    -------------------------------------------------------------
**    I make no representations or warranties about the suitability of
**    the software, either express or implied, including but not limited
**    to the implied warranties of merchantability, fitness for a
**    particular purpose, or non-infringement. I shall not be liable for
**    any damages suffered by licensee as a result of using, modifying or
**    distributing this software or its derivatives.
*/

/**
 *    @author Dario de Judicibus
 *    @version 1.0.0
 *    @see jdk 1.1
 */
import java.io.* ;
import java.net.* ;
import java.util.Date ;
import java.text.SimpleDateFormat ;

class SampleClient
{
    // CLASS VARIABLES
    private static final int     cvPORT = 2000 ;
    private static final String     cvDATEFORMAT = "EEE dd MMM yyyy HH:mm:ss z" ;

    // INSTANCE VARIABLES
    private String             ivHostName ;
    private String             ivServerAddress ;
    private Socket            ivClientSocket ;
    private BufferedReader        ivFromServerStream ;
    private PrintWriter        ivToServerStream ;
    private SimpleDateFormat    ivFormatter ;

    public static void main( String[] args )
    {
        String givenAddress = null ;

        if ( args.length == 1 )
        {
            givenAddress = args[ 0 ] ;
        }

        SampleClient sampleClient = new SampleClient( givenAddress ) ;
        sampleClient.run( ) ;
    }

    private SampleClient( String serverAddress )
    {
        ivServerAddress = serverAddress ;
        ivFormatter = new SimpleDateFormat( cvDATEFORMAT ) ;

        System.out.println( "[" + ivFormatter.format( new Date( ) ) + "] " + "Starting client." ) ;
    }

    private void run( )
    {
        // Try to create a client socket first.
        // If fails, just abend the client.
        try
        {
              createClientSocket( ) ;
        }
        catch ( UnknownHostException exc )
        {
            System.out.println( "[ERROR] Unknown host: " + exc.getMessage( ) ) ;
            System.exit( 1 ) ; // Terminate server
        }
        catch ( IOException exc )
        {
            System.out.println( "[ERROR] IO: " + exc.getMessage( ) ) ;
            System.exit( 1 ) ; // Terminate server
        }

        // Manage interactions with server.
        // If fails, print the stack trace and abend the client.
        try
        {
            // Prepare for data exchange
            prepareForExchange( ) ;

            int c ;
            String inputLine ;
                  StringBuffer outputLine = new StringBuffer( 50 ) ;

            // Process input from server until closing
            while ( ( inputLine = ivFromServerStream.readLine( ) ) != null )
            {
                System.out.println( "[SERVER] " + inputLine ) ;
                if ( inputLine.equals( "OK Closing server." ) )
                            break ;

                while ( ( c = System.in.read( ) ) != '\n' )
                {
                    outputLine.append( (char)c ) ;
                }

                System.out.println("[CLIENT] " + outputLine ) ;
                ivToServerStream.println( outputLine.toString( ) ) ;

                outputLine.setLength( 0 ) ;
            }

            // Terminate session and close connection
            terminateConnection( ) ;

        }
        catch ( UnknownHostException exc )
        {
            System.out.println( "[ERROR] Unknown host: " + exc.getMessage( ) ) ;
            System.exit( 1 ) ; // Terminate server
        }
        catch ( IOException exc )
        {
            System.out.println( "[ERROR] IO: " + exc.getMessage( ) ) ;
            System.exit( 1 ) ; // Terminate server
        }
    }

    private void createClientSocket( ) throws UnknownHostException,IOException
    {
        InetAddress serverAddress ;

        try
        {
            serverAddress = InetAddress.getByName( ivServerAddress ) ;
        }
        catch ( UnknownHostException exc )
        {
            serverAddress = InetAddress.getByName( null ) ;

        }

        ivHostName = serverAddress.getHostName( ) ;

        ivClientSocket = new Socket( ivHostName, cvPORT ) ;

        System.out.println( "[" + ivFormatter.format( new Date( ) ) + "] "
            + "Connecting to server " + ivHostName + " on port " + cvPORT ) ;

        return ;
    }

    private void prepareForExchange( ) throws IOException
    {
        // Create the input and output streams
        // Both streams are buffered
               ivFromServerStream = new BufferedReader(
            new InputStreamReader(  ivClientSocket.getInputStream( ) ) ) ;

               ivToServerStream = new PrintWriter(    ivClientSocket.getOutputStream( ), true ) ;

        System.out.println( "[" + ivFormatter.format( new Date( ) ) + "] " + "Client ready" ) ;

        return ;
    }

    private void terminateConnection( ) throws IOException
    {
            ivToServerStream.close( ) ;
            ivFromServerStream.close( ) ;
            ivClientSocket.close( ) ;

        System.out.println( "[" + ivFormatter.format( new Date( ) ) + "] "
            + "Closing connection from " + ivHostName ) ;

        // Reset all instance variables
            ivToServerStream = null ;
            ivFromServerStream = null ;
            ivClientSocket = null ;

        return ;
    }
}