Client Implementation

Listing 11.4 RemoteClientImpl.java

//import packages 
import java.rmi.*;
import java.rmi.server.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

//client implementation
public class RemoteClientImpl extends 
	JFrame implements ClientInterface {

  //variable declaration
  private JButton btnSend;
  private JTextArea txtReceive,txtPass;
  private ServerInterface server;

  //constructor
  public RemoteClientImpl()
	 throws RemoteException{
	
	super("Remote Client"); 	 
	System.out.println("Creating remote client");
	this.setup();
  }

  //method used to create various components
  private void setup(){
	
	//get the content pane object
	Container cp = getContentPane();

	//panel for buttons
	JPanel btnPanel = new JPanel();

	//text area used to show received messages.
	txtReceive = new JTextArea(15,45);
	txtReceive.setBorder(BorderFactory.createTitledBorder(
	"Messages Received"));
	txtReceive.setEditable(false);
	
	//text area for typing messages.
	txtPass = new JTextArea(5,45);
	txtPass.setBorder(BorderFactory.createTitledBorder(
	"Type your message here"));

	//button to post a message
	btnSend = new JButton("Send Message");

	//add action listener
	btnSend.addActionListener(new ButtonHandler());
	
	JScrollPane 
	 cPane = new JScrollPane(txtReceive),
	 sPane = new JScrollPane(txtPass);

	//add all the components 
	btnPanel.add(btnSend);
	cp.add(cPane,BorderLayout.NORTH);
	cp.add(sPane,BorderLayout.CENTER);
	cp.add(btnPanel,BorderLayout.SOUTH);

	//method used to register with the server
	register();
	
	//set default close operation
	this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	//pack the frame and show it
	pack();
	show();
	txtPass.requestFocus();
   }
	
  //method used to register with the server
  private void register(){
	try{

	 //get a remote reference
	 server = (ServerInterface)Naming.lookup("Server");
		 
	 //export the object explicitly
	 UnicastRemoteObject.exportObject(this);
		 
	 //get registered with the server
	 server.getRegistered(this);
	 txtReceive.append("Registered with the server");
	 }catch(Exception ex){
	 	txtReceive.append(ex.getMessage()); 
	 }
   }


  //remote method used to post a message to the
  //client.
  public void passMessage(String message)
	throws RemoteException{
	txtReceive.append(message);
  }


  //create an instance of the client	
  public static void main(String args[]){
	try{
	 RemoteClientImpl cl = new RemoteClientImpl();
	}catch(Exception ex){
		System.out.println(ex.getMessage());
	}
   }


  //event handling class
  private class ButtonHandler 
	implements ActionListener{

	 public void actionPerformed(ActionEvent ae){
	    try{

	       //post message to the server
	       server.passMessage("\n"+txtPass.getText());
	       txtPass.setText("");
	       txtPass.requestFocus();
	      }catch(Exception ex){
 		 txtReceive.append(ex.getMessage());
 	      }
	   }
     }
}