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Panda Nets is a client side library of many basic Internet protocols.

There is a newer version: 1.8.0

package panda.net.echo;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;

import panda.net.discard.DiscardUDPClient;

/***
 * The EchoUDPClient class is a UDP implementation of a client for the Echo protocol described in
 * RFC 862. To use the class, just open a local UDP port with
 * {@link panda.net.DatagramSocketClient#open open } and call {@link #send send } to send datagrams
 * to the server, then call {@link #receive receive } to receive echoes. After you're done echoing
 * data, call {@link panda.net.DatagramSocketClient#close close() } to clean up properly.
 * 
 * @see EchoTCPClient
 * @see DiscardUDPClient
 ***/

public final class EchoUDPClient extends DiscardUDPClient {
	/*** The default echo port. It is set to 7 according to RFC 862. ***/
	public static final int DEFAULT_PORT = 7;

	private final DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);

	/***
	 * Sends the specified data to the specified server at the default echo port.
	 * 
	 * @param data The echo data to send.
	 * @param length The length of the data to send. Should be less than or equal to the length of
	 *            the data byte array.
	 * @param host The address of the server.
	 * @exception IOException If an error occurs during the datagram send operation.
	 ***/
	@Override
	public void send(byte[] data, int length, InetAddress host) throws IOException {
		send(data, length, host, DEFAULT_PORT);
	}

	/*** Same as  send(data, data.length, host)  ***/
	@Override
	public void send(byte[] data, InetAddress host) throws IOException {
		send(data, data.length, host, DEFAULT_PORT);
	}

	/***
	 * Receives echoed data and returns its length. The data may be divided up among multiple
	 * datagrams, requiring multiple calls to receive. Also, the UDP packets will not necessarily
	 * arrive in the same order they were sent.
	 * 
	 * @param data the buffer to receive the input
	 * @param length of the buffer
	 * @return Length of actual data received.
	 * @exception IOException If an error occurs while receiving the data.
	 ***/
	public int receive(byte[] data, int length) throws IOException {
		__receivePacket.setData(data);
		__receivePacket.setLength(length);
		_socket_.receive(__receivePacket);
		return __receivePacket.getLength();
	}

	/***
	 * Same as  receive(data, data.length)
	 * 
	 * @param data the buffer to receive the input
	 * @return the number of bytes
	 * @throws IOException on error
	 ***/
	public int receive(byte[] data) throws IOException {
		return receive(data, data.length);
	}

}