Server.java

/**
 * @author Hamid(the6ixdev)
 * This Program can sit on a public server
 */

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

public class Server extends JFrame {
	
	// This is gonna be the area that u type ur message
	private JTextField userText;
	// now the area that shows the conversation
	private JTextArea chatWindow;
	// we need to build a Stream
	/*
	 * Stream as a method to send data between our 2 computers
	 * two types ->input stream & output Stream
	 * we send it packed like as a boat through output stream
	 * and vice versa
	 */
	private ObjectOutputStream output;
	private ObjectInputStream input;
	
	
	private ServerSocket server;
	
	// In java connections are called Socket, setup the socket
	// means setup the connection
	private Socket connection;
	
	
	/*
	 *  Setup the GUI
	 * constructor
	 * */
	
	public Server() {
		
		super("Server Side Instant Messenger!");
		userText = new JTextField();
		// by default before u connect don't edit this
		userText.setEditable(false);
		// now let's add actionListener to it
		userText.addActionListener(
				new ActionListener() {
					@Override
					public void actionPerformed(ActionEvent event) {
						sendMessage(event.getActionCommand());
						userText.setText("");
					}
				}
			);
		add(userText,BorderLayout.NORTH);
		chatWindow = new JTextArea();
		add(new JScrollPane(chatWindow));
		setSize(700,400);
		setVisible(true);
		
	}
	
	// setup the application and run the server
	
	public void startRunning() throws IOException {
		try{
			// time to set it
			// when our package comes to stream,it wants a port number
			// second variable is, how many are allowed to talk to me at a time?
			// 100 is called a backlog or queue length
			
			server = new ServerSocket(6789,100);
			while(true) {
				try {
					// connect and have conversation
					waitForConnection();
					setupStreams();
					whileChatting();
					
				} catch (EOFException eofException) {
					// when conversation ,end of stream
					showMessage("\nServer ended the connection! ");
				}finally{
					closeStuff();
					}
			}
			}catch(IOException ioException) {
			// print so we know where we went wrong
			ioException.printStackTrace();
		}
		
	}

			
				
				
			
		
	
	

	// wait for connection, then display connection information
	private void waitForConnection() throws IOException {
		showMessage("Waiting for someone to connect... \n");
		// now we need to setup the connection between u and the other computer(aka socket)
		// the loop is called over and over and accepts connections
		connection = server.accept();
		//socket is created
		showMessage("Now connected to "+connection.getInetAddress().getHostName());

	}
	
	
	// setting up the streams
	private void setupStreams() throws IOException {
		// setting up the pathway to send stuff
		output = new ObjectOutputStream(connection.getOutputStream());
		// when data is stuck
		// just in case you will flush out of streams
		output.flush();
		//setting up the pathway to receive stuff
		input = new ObjectInputStream(connection.getInputStream());
		showMessage("\n the streams are not setup! \n");
	}
	
	
	
	
	// during the chat conversation
	private void whileChatting() throws IOException {
		
	String message = "You are now connected!";
	sendMessage(message);
	ableToType(true);
	//during the conversation we r gonna put everything in a do-while loop
	
	do {
		// have a conversation while both of us want to
		// if user says "end" its done
		try {
			// we wanna make stream a string type.
			message = (String)input.readObject();
			showMessage("\n" + message);
		} catch (ClassNotFoundException classNotFoundException) {
			showMessage("\n I don't know what user sent! ");
		}
	} while (!message.equals("MOZHGAN: END"));	
   }
	
	
	
	
	
	// close streams and sockets after done chatting

	private void closeStuff() {
		showMessage("\n Closing connections.... \n");
		ableToType(false);
		
		try {
			output.close();
			input.close();
			connection.close();
			
		} catch (IOException ioException) {
			// TODO: handle exception
			ioException.printStackTrace();
		}
	}
	
	
	
	
	// send a message to client
	private void sendMessage(String message) {
		try {
			// send message from output stream
			output.writeObject("Hamid: "+message);
			output.flush();
			showMessage("\nHamid: "+message);
			
		} catch(IOException ioException) {
			// TODO: handle exception
			chatWindow.append("\n ERROR: MESSAGE COULD NOT BE SENT! ");
		}
	}
	
	
	
	// updates chat window

	private void showMessage(final String text) {
		// the only thing we wanna update is part of the GUI
		// so we have to use one of the Javax swing stuff
		// so it sets a thread that updates parts of the GUI
		SwingUtilities.invokeLater(
				new Runnable() {
					public void run() {
						chatWindow.append(text);
					}
				}
				);
	}
	
	
	// let the user type into their box
	
	private void ableToType(final boolean tof) {
		SwingUtilities.invokeLater(
				new Runnable() {
					@Override
					public void run() {
						userText.setEditable(tof);					
						}
				}
				);
		
	}
	
	
	
	
}