An Echo Client Based on UDP Sockets - Java Network

Java examples for Network:UDP

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Description

An Echo Client Based on UDP Sockets

Demo Code

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class Main {
  public static void main(String[] args) throws Exception {
    DatagramSocket udpSocket = new DatagramSocket();
    String msg = null;// ww  w. j  a va2  s  .c  om
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String promptMsg = "Please enter a message (Bye to quit):";
    System.out.print(promptMsg);
    while ((msg = br.readLine()) != null) {
      if (msg.equalsIgnoreCase("bye")) {
        break;
      }
      DatagramPacket packet = getPacket(msg);
      udpSocket.send(packet);
      udpSocket.receive(packet);
      displayPacketDetails(packet);
      System.out.print(promptMsg);
    }
    udpSocket.close();
  }

  public static void displayPacketDetails(DatagramPacket packet) {
    byte[] msgBuffer = packet.getData();
    int length = packet.getLength();
    int offset = packet.getOffset();
    int remotePort = packet.getPort();
    InetAddress remoteAddr = packet.getAddress();
    String msg = new String(msgBuffer, offset, length);
    System.out.println("[Server at IP Address=" + remoteAddr + ", port="
        + remotePort + "]: " + msg);

    System.out.println();
  }

  public static DatagramPacket getPacket(String msg)
      throws UnknownHostException {
    final int PACKET_MAX_LENGTH = 1024;
    byte[] msgBuffer = msg.getBytes();

    int length = msgBuffer.length;
    if (length > PACKET_MAX_LENGTH) {
      length = PACKET_MAX_LENGTH;
    }

    DatagramPacket packet = new DatagramPacket(msgBuffer, length);

    int serverPort = 15900;
    final String SERVER__NAME = "localhost";
    InetAddress serverIPAddress = InetAddress.getByName(SERVER__NAME);
    packet.setAddress(serverIPAddress);
    packet.setPort(serverPort);

    return packet;
  }
}

Result


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