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 16-2 sets up a Java network client, using IOException to catch errors.
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 Recipe 18.7). You can write code so that it will run from a URL, when opened in a web browser, or from an application.