NETWORKING - Introduction to Java Programming: Comprehensive Version - page 1148

System.out.println( "Client's IP Address is " +
inetAddress.getHostAddress());

You can also create an instance of InetAddress from a host name or IP address using the
static getByName method. For example, the following statement creates an InetAddress
for the host liang.armstrong.edu .

InetAddress address = InetAddress.getByName( "liang.armstrong.edu" );

Listing 31.3 gives a program that identifies the host name and IP address of the arguments
you pass in from the command line. Line 7 creates an InetAddress using the getByName
method. Lines 8 and 9 use the getHostName and getHostAddress methods to get the
host's name and IP address. Figure 31.7 shows a sample run of the program.

F IGURE 31.7

The program identifies host names and IP addresses.

L ISTING 31.3

IdentifyHostNameIP.java
1 import java.net.*;
2
3 public class IdentifyHostNameIP {
4 public static void main(String[] args) {
5 for ( int i = 0 ; i < args.length; i++) {
6 try {
7 InetAddress address = InetAddress.getByName(args[i]);
8 System.out.print( "Host name: " + address.getHostName() + " " );
9 System.out.println( "IP address: " + address.getHostAddress());
10 }
11 catch (UnknownHostException ex) {
12 System.err.println( "Unknown host or IP address " + args[i]);
13 }
14 }
15 }
16 }

get an InetAddress
get host name
get host IP

31.6 How do you obtain an instance of InetAddress ?
31.7 What methods can you use to get the IP address and hostname from an
InetAddress ?

✓ ✓

Check

Point

31.4 Serving Multiple Clients
A server can serve multiple clients. The connection to each client is handled by one
thread.

Key
Point

Multiple clients are quite often connected to a single server at the same time. Typically, a
server runs continuously on a server computer, and clients from all over the Internet can con-
nect to it. You can use threads to handle the server's multiple clients simultaneously—simply