Unicast messaging is used for all network processes in which a private or unique resource is requested.
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import javax.swing.JFrame;
public class Unicast extends JFrame implements ActionListener{
Label entermsgl,receivedmsgl,sentmsgl,toportl;
TextField entermsg,toport;
TextArea receivedmsg,sentmsg;
Button send,exit;
int myport;
DatagramSocket ds;
DatagramPacket dp;
Unicast(){
new InputDialog(this);
}
public void initialise(){
setTitle("Unicast --Port:"+myport);
setVisible(true);
setSize(600,400);
entermsgl=new Label("Enter Message:");
receivedmsgl=new Label("Received Messages:");
sentmsgl=new Label("Sent Messages:");
toportl=new Label("To");
toport=new TextField();
entermsg=new TextField();
receivedmsg=new TextArea();
sentmsg=new TextArea();
send=new Button("Send");
exit=new Button("Exit");
setLayout(null);
add(entermsgl);
entermsgl.setBounds(25,25,100,25);
add(receivedmsgl);
receivedmsgl.setBounds(25,70,150,25);
add(sentmsgl);
sentmsgl.setBounds(25,185,150,25);
add(toportl);
toportl.setBounds(350,25,25,25);
add(toport);
toport.setBounds(380,25,70,25);
add(entermsg);
entermsg.setBounds(130,25,200,25);
add(receivedmsg);
receivedmsg.setBounds(180,70,370,100);
add(sentmsg);
sentmsg.setBounds(180,185,370,100);
add(send);
send.setBounds(470,25,100,25);
add(exit);
exit.setBounds(250,300,100,25);
try{
ds=new DatagramSocket(myport);
}catch(Exception e){
System.out.println(e);
}
send.addActionListener(this);
exit.addActionListener(this);
new Receive();
}
class Receive extends Thread{
Receive(){
start();
}
public void run(){
while(true){
try{
byte b[]=new byte[100];
dp=new DatagramPacket(b,b.length);
ds.receive(dp);
receivedmsg.append("From "+dp.getPort()+": "+new String(dp.getData(),0,dp.getLength())+"n");
}catch(Exception e){
}
}
}
}
public void actionPerformed(ActionEvent ae){
if(ae.getSource()==send){
byte b[]=entermsg.getText().getBytes();
try{
int port=Integer.parseInt(toport.getText());
if(port<1024 || port>65536){
toport.setText("");
return;
}
dp=new DatagramPacket(b,b.length,InetAddress.getLocalHost(),port);
ds.send(dp);
sentmsg.append("To "+port+": "+entermsg.getText()+"n");
}catch(NumberFormatException nfe){
toport.setText("");
}catch(Exception e){
}
}
else{
System.exit(0);
}
}
public static void main(String args[]){
new Unicast();
}
}
class InputDialog extends Dialog implements ActionListener{
Button ok=new Button("Ok");
Button cancel=new Button("Cancel");
TextField tf=new TextField();
Label l=new Label("Enter the port number:");
Unicast parent;
InputDialog(Unicast f){
super(f,"Unicast - Port number");
parent=f;
setVisible(true);
setSize(400,200);
setLayout(null);
add(l);
l.setBounds(25,50,200,25);
add(tf);
tf.setBounds(225,50,100,25);
add(ok);
ok.setBounds(100,100,100,25);
add(cancel);
cancel.setBounds(220,100,100,25);
ok.addActionListener(this);
cancel.addActionListener(this);
}
public void actionPerformed(ActionEvent ae){
if(ae.getSource()==ok){
try{
int n=Integer.parseInt(tf.getText());
if(n>1023 && n<65536){
parent.myport=n;
parent.initialise();
this.dispose();
}
else{
tf.setText("");
tf.requestFocus();
}
}catch(NumberFormatException nfe){
tf.setText("");
tf.requestFocus();
}
}
else if(ae.getSource()==cancel){
System.exit(0);
}
}
}
