UDP DatagramSocket Socket programming in JAVA (Client, Server Example )

In this post, we will write simple UDP Datagram client and server in JAVA language. The client sends simple string to server.

 $ vim DatagramSenderClient.java 

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class DatagramSenderClient{
        private static String remoteServerAddr = "192.168.1.102";
        private static int remoteServerPort = 5555;

        public static void main(String[] args) throws Exception {
                DatagramSocket localSocket = new DatagramSocket();

                String message = "This is string sent from DatagramSenderClient.java Client";
                InetAddress remoteServerInetAddr = InetAddress.getByName(remoteServerAddr);
                DatagramPacket dataGramPacket = new DatagramPacket(message.getBytes(), message.length(), remoteServerInetAddr, remoteServerPort);

                localSocket.send(dataGramPacket);
                localSocket.close();
        }

}

compile the client program as, [ Note: if you don’t have JAVA installed, follow “How to Install Java using apt-get command on Ubuntu” ]

 $ javac DatagramSenderClient.java 

Now, lets write a server program which will receive the data sent from the client.

 $ vim DatagramReceiverServer.java

import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class DatagramReceiverServer {
        private static int remoteServerPort = 5555;

        public static void main(String[] args) throws Exception {

                DatagramSocket localServerSocket = new DatagramSocket(remoteServerPort);
                byte[] buf = new byte[1024];

                DatagramPacket datagramReceiverPacket = new DatagramPacket(buf, 1024);
                localServerSocket.receive(datagramReceiverPacket);

                String receivedMessage = new String(datagramReceiverPacket.getData(), 0, datagramReceiverPacket.getLength());
                System.out.println(receivedMessage);
                localServerSocket.close();
        }

}

 $ javac DatagramReceiverServer.java 

 $ java DatagramReceiverServer 

 $ java DatagramSenderClient 

$ java DatagramReceiverServer
This is string sent from DatagramSenderClient.java Client