broadcasterclient.java

来自「java 完全探索的随书源码」· Java 代码 · 共 103 行

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;

public class BroadcasterClient extends Thread
{
  // Set a default listener port
  private int listenerPort = 59;
  private DatagramSocket listenerSocket = null;
  private static int MAX_PACKET_SIZE = 1000;

  // Default Constructor
  public BroadcasterClient()
  {
    super();
  }

  // Alternate Constructor to Override Port
  public BroadcasterClient( int newPort )
  {
    // overide port setting
    listenerPort = newPort;
  }

  public void run()
  {
    byte[] buffer = new byte[ MAX_PACKET_SIZE ];
    // Create a packet to hold the data when it arrives
    DatagramPacket infoPacket = new DatagramPacket( buffer, MAX_PACKET_SIZE );

    try
    {
      listenerSocket = new DatagramSocket( this.listenerPort );
    }
    catch( Exception ex )
    {
      System.out.println( "Problem creating socket on port: " + listenerPort );
      System.exit( -1 );
    }

    // do an infinite loop
    while( true )
    {
      try
      {
        System.out.println( "Waiting on broadcasts..." );
        // Setting this value to 0 causes it to be an infinite timeout
        listenerSocket.setSoTimeout( 0 );
        listenerSocket.receive( infoPacket );

        // What address sent the packet
        InetAddress fromAddress = infoPacket.getAddress();
        // Get the message within the packet
        byte[] msg = infoPacket.getData();

        System.out.println( "Received broadbast from " + fromAddress );
        System.out.println( new String(msg) );
      }
      catch( IOException ex )
      {
        // Print the exception and try to keep going
        ex.printStackTrace();
      }
    }
  }

  public static void main( String[] args )
  {
    BroadcasterClient client = null;
    int argLength = args.length;
    // Make sure the correct number of args were passed
    if ( argLength > 1 )
    {
      System.out.println( "Usage: java BroadcasterClient <port>" );
      System.exit( 0 );
    }

    if ( argLength == 0 )
      client = new BroadcasterClient();

    if ( argLength == 1 )
    {
      int port = 0;

      String arg = args[0];
      try
      {
        port = Integer.parseInt( arg );
      }
      catch( Exception ex )
      {
        System.out.println( "Invalid port specified on the command line:arg" );
        System.exit( -1 );
      }

      client = new BroadcasterClient( port );
    }

    // Listen for messages
    client.start();
  }
}