packetreceivedemo.java

Java网络编程与分布式计算, 主要分析java网络各方面的编程, 提供许多实用安全

import java.net.*;
import java.io.*;

// Chapter 5, Listing 1
public class PacketReceiveDemo 
{
	public static void main (String args[])
	{
		try
		{
			System.out.println ("Binding to local port 2000");

			// Create a datagram socket, bound to the specific port 2000
			DatagramSocket socket = new DatagramSocket(2000);

			System.out.println ("Bound to local port " + socket.getLocalPort());

			// Create a datagram packet, containing a maximum buffer of 256 bytes
			DatagramPacket packet = new DatagramPacket( new byte[256], 256 );

			// Receive a packet - remember by default this is a blocking operation
			socket.receive(packet);

			System.out.println ("Packet received!");

			// Display packet information
			InetAddress remote_addr = packet.getAddress();
			System.out.println ("Sent by  : " + remote_addr.getHostAddress() );
			System.out.println ("Send from: " + packet.getPort());

			// Display packet contents, by reading from byte array
			ByteArrayInputStream bin = new ByteArrayInputStream (packet.getData());

			// Display only up to the length of the original UDP packet
			for (int i=0; i < packet.getLength(); i++)
			{
				int data = bin.read();
				if (data == -1)
					break;
				else
					System.out.print ( (char) data) ;
			}
			
			socket.close();
		}
		catch (IOException ioe)
		{
			System.err.println ("Error - " + ioe);
		}

	}
}