The ByteBuffer Class (from the java.nio package) helps you to write data in UDP by converting them to the respective bytes they generally occupy. This is especially helpful when trying to control network traffic.
The example code, by default, has the same computer as the destination and a port 10001 as the listening port. A different process can listen on this port and receive the UDP message sent by this application.
The Code:import java.net.*;import java.io.*;import java.nio.*;public class SendUDPData{private String serverIP = "127.0.0.1";private int listeningPort = 10001;private DatagramSocket datagramSocket = null;public static void main(String args[]){SendUDPData sendUDPData = new SendUDPData();sendUDPData.sendData();}private void sendData(){try{// Initializing a byte Arraybyte[] byteDataArr = new byte[10];ByteBuffer configDataBuffer = ByteBuffer.wrap(byteDataArr);// Initializing the variablesint configRackID = 12;int configPortID = 760;//populating the configDataBuffer with the required values.//Will populate the first 4 bytesconfigDataBuffer.putInt(configRackID);//Will populate the second 4 bytesconfigDataBuffer.putInt(configPortID);// and so on...//Two ways of creating a datagramSocket. Can use the one required//Will create a DatagramSocket on port 10000datagramSocket = new DatagramSocket(10000);//Will create a DatagramSocket on any available portdatagramSocket = new DatagramSocket();//Will connect to the IPAddress provided by the serverIP and to theport specified by listeningPortdatagramSocket.connect(InetAddress.getByName(serverIP),listeningPort);datagramSocket.send(new DatagramPacket(byteDataArr,byteDataArr.length));datagramSocket.close();System.out.println("Data sent successfully.");}catch(SocketException se){//handle SocketExceptionSystem.out.println("SocketException: "+se);}catch(UnknownHostException uhe){//handle UnknownHostExceptionSystem.out.println("UnknownHostException: "+uhe);}catch(IOException ioe){//handle IOExceptionSystem.out.println("IOException: "+ioe);}catch(Exception e){//handle ExceptionSystem.out.println("Exception: "+e);}finally{if (datagramSocket != null)datagramSocket.close();}}}
