Minimal Server

In this example, the client connects to the server and the server returns a "canned" message and breaks the connection. Thus, the client and server programs function at the "Hello, World!" level.

The important functionality of this server is located in the runServer method. A minimal user interface is created in the constructor, and the program is driven from the main method.

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

public class Server_Basic extends Frame implements WindowListener{

ServerSocket listenSocket;
Socket connection;

OutputStream outStream;
DataOutputStream outDataStream;

TextArea logDisplay;
String message;

  public Server_Basic ()  {

    super ( "Server_Basic" );
    logDisplay = new TextArea ( 40, 10 );
    add ( "Center", logDisplay );
    addWindowListener ( this );
    resize ( 400, 300 );
    show ();

  }  // end Server_Basic constructor

// **************

  public void runServer ( )  {

    try  {

      listenSocket = new ServerSocket ( 8901 );
      logDisplay.setText ( "Server started " );

      try {
        InetAddress here = InetAddress.getLocalHost ();
        String host = here.getHostName ();
        logDisplay.appendText ( "on "+host+", port 8901\n" );
        }
      catch (UnknownHostException e) {
        logDisplay.setText ( "Problem with local host\n" );
        }

      connection = listenSocket.accept ();
      logDisplay.appendText ( "Connection request received\n" );

      outStream = connection.getOutputStream ();
      outDataStream = new DataOutputStream ( outStream );

      message = new String ( "Hello, Client, from Server!" );
      outDataStream.writeUTF ( message );
      logDisplay.appendText ( "Text sent to client: \n" );
      logDisplay.appendText ( "  "+message+"\n" );
      logDisplay.appendText ( "Closing socket\n" );
      connection.close ();

    }  // end try

    catch ( IOException except)  {
      except.printStackTrace ();
    }  // end catch

  }  // end runServer

// **************

  public static void main ( String [ ] args )  {

    Server_Basic server = new Server_Basic ();

    server.runServer ();

  }  // end main



  //***********  Utility Methods   ***********



  //***********  Interface Methods   ***********


  //****  WindowListener methods

  public void windowActivated ( WindowEvent e )  {
  }

  public void windowDeactivated ( WindowEvent e )  {
  }

  public void windowOpened ( WindowEvent e )  {
  }

   public void windowClosed ( WindowEvent e )  {
  }

  public void windowClosing ( WindowEvent e )  {
    this.hide ();
    this.dispose ();
    System.exit(0);
  }

  public void windowIconified ( WindowEvent e )  {
  }

  public void windowDeiconified ( WindowEvent e )  {
  }



}  // end Server_Basic