There isn’t much to this in Java, in fact. When creating a
socket, you pass in the
hostname and the port
number. The
java.net.Socket
constructor does the
gethostbyname( )
and the
socket( )
system call, sets up the server’s
sockaddr_in
structure, and executes the
connect( )
call. All you have to do is catch the errors, which are subclassed
from the familiar
IOException
.
Example 15.2 sets up a Java network client, using
IOException
to catch errors.
Example 15-2. Connect.java (simple client connection)
import java.net.*; /* * A simple demonstration of setting up a Java network client. */ public class Connect { public static void main(String[] argv) { String server_name = "localhost"; try { Socket sock = new Socket(server_name, 80); /* Finally, we can read and write on the socket. */ System.out.println(" *** Connected to " + server_name + " ***"); /* . do the I/O here .. */ sock.close( ); } catch (java.io.IOException e) { System.err.println("error connecting to " + server_name + ": " + e); return; } } }
Java supports other ways of using network applications. You can also open a URL and read from it (see Section 17.7). You can write code so that it will run from a URL, when opened in a web browser, or from an application (see Section 17.10).
18.118.12.186