www.pudn.com > jnp-src.rar > InetExample.java

/*
 * Java Network Programming, Second Edition
 * Merlin Hughes, Michael Shoffner, Derek Hamner
 * Manning Publications Company; ISBN 188477749X
 *
 * http://nitric.com/jnp/
 *
 * Copyright (c) 1997-1999 Merlin Hughes, Michael Shoffner, Derek Hamner;
 * all rights reserved; see license.txt for details.
 */

import java.net.*; 
import java.io.*; 
 
public class InetExample { 
  public static void main (String args[]) { 
    printLocalAddress (); 
    Reader kbd = new FileReader (FileDescriptor.in); 
    BufferedReader bufferedKbd = new BufferedReader (kbd); 
    try { 
      String name; 
      do { 
        System.out.print ("Enter a hostname or IP address: "); 
        System.out.flush (); 
        name = bufferedKbd.readLine (); 
        if (name != null) 
          printRemoteAddress (name); 
      } while (name != null); 
      System.out.println ("exit"); 
    } catch (IOException ex) { 
      System.out.println ("Input error:"); 
      ex.printStackTrace (); 
    } 
  } 
 
  static void printLocalAddress () { 
    try { 
      InetAddress myself = InetAddress.getLocalHost (); 
      System.out.println ("My name : " + myself.getHostName ()); 
      System.out.println ("My IP : " + myself.getHostAddress ()); 
      System.out.println ("My class : " + ipClass (myself.getAddress ())); 
    } catch (UnknownHostException ex) { 
      System.out.println ("Failed to find myself:"); 
      ex.printStackTrace (); 
    } 
  } 
 
  static char ipClass (byte[] ip) { 
    int highByte = 0xff & ip[0]; 
    return (highByte < 128) ? 'A' : (highByte < 192) ? 'B' : 
      (highByte < 224) ? 'C' : (highByte < 240) ? 'D' : 'E'; 
  } 
 
  static void printRemoteAddress (String name) { 
    try { 
      System.out.println ("Looking up " + name + "..."); 
      InetAddress machine = InetAddress.getByName (name); 
      System.out.println ("Host name : " + machine.getHostName ()); 
      System.out.println ("Host IP : " + machine.getHostAddress ()); 
      System.out.println ("Host class : " + 
                          ipClass (machine.getAddress ())); 
    } catch (UnknownHostException ex) { 
      System.out.println ("Failed to lookup " + name); 
    } 
  }  
}