Network Clients - Java - page 537

you to examine a number of files to see which ones are ready for reading or writing. Java
does not support this model. The other model, which works on most platforms and is the
norm in Java, is to use two threads, [ 44 ] one to handle the data transfer in each direction. That
is our plan here; the class Pipe encapsulates one thread and the code for copying data in one
direction; two instances are used, one to drive each direction of transfer independently of the
other.

This program allows you to connect to any text-based network service. For example, you can
talk to your system's SMTP (simple mail transport protocol) server, or the Daytime server
(port 13) used in several earlier recipes in this chapter:

$ java network.Telnet darian 13
Host darian; port 13
Connected OK
Sat Apr 28 14:07:41 2001
^C
$

The source code is shown in Example 13-11 .

Example 13-11. Telnet.java
public public class Telnet {

String host ;
int

class Telnet

int portNum ;
public

public static static void void main ( String [] argv ) {

new new Telnet (). talkTo ( argv );

}
private private void void talkTo ( String av []) {

iif ( av . length >= 1 )
host = av [ 0 ];

else else

host = "localhost" ;
iif ( av . length >= 2 )
portNum = Integer . parseInt ( av [ 1 ]);

else else portNum = 23 ;

System . out . println ( "Host " + host + "; port " + portNum );
try

try {
Socket s = new new Socket ( host , portNum );

// Connect the remote to our stdout
new new Pipe ( s . getInputStream (), System . out ). start ();

// Connect our stdin to the remote