Java example source code file (Connect.java)

This example Java source code file (Connect.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

actor, bytebuffer, charbuffer, connect, datagramchannel, exception, from, inetaddress, inetsocketaddress, ioexception, net, network, nio, reactor, sprintable, thread, us\-ascii

The Connect.java Java example source code

/*
 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/* @test
 * @bug 4313882 7183800
 * @summary Test DatagramChannel's send and receive methods
 * @author Mike McCloskey
 */

import java.io.*;
import java.net.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;


public class Connect {

    static PrintStream log = System.err;

    public static void main(String[] args) throws Exception {
        test();
    }

    static void test() throws Exception {
        Reactor r = new Reactor();
        Actor a = new Actor(r.port());
        invoke(a, r);
    }

    static void invoke(Sprintable reader, Sprintable writer) throws Exception {

        Thread writerThread = new Thread(writer);
        writerThread.start();

        Thread readerThread = new Thread(reader);
        readerThread.start();

        writerThread.join();
        readerThread.join();

        reader.throwException();
        writer.throwException();
    }

    public interface Sprintable extends Runnable {
        public void throwException() throws Exception;
    }

    public static class Actor implements Sprintable {
        final int port;
        Exception e = null;

        Actor(int port) {
            this.port = port;
        }

        public void throwException() throws Exception {
            if (e != null)
                throw e;
        }

        public void run() {
            try {
                DatagramChannel dc = DatagramChannel.open();

                // Send a message
                ByteBuffer bb = ByteBuffer.allocateDirect(256);
                bb.put("hello".getBytes());
                bb.flip();
                InetAddress address = InetAddress.getLocalHost();
                if (address.isLoopbackAddress()) {
                    address = InetAddress.getLoopbackAddress();
                }
                InetSocketAddress isa = new InetSocketAddress(address, port);
                dc.connect(isa);
                dc.write(bb);

                // Try to send to some other address
                address = InetAddress.getLocalHost();
                InetSocketAddress bogus = new InetSocketAddress(address, 3333);
                try {
                    dc.send(bb, bogus);
                    throw new RuntimeException("Allowed bogus send while connected");
                } catch (IllegalArgumentException iae) {
                    // Correct behavior
                }

                // Read a reply
                bb.flip();
                dc.read(bb);
                bb.flip();
                CharBuffer cb = Charset.forName("US-ASCII").
                newDecoder().decode(bb);
                log.println("From Reactor: "+isa+ " said " +cb);

                // Clean up
                dc.disconnect();
                dc.close();
            } catch (Exception ex) {
                e = ex;
            }
        }
    }

    public static class Reactor implements Sprintable {
        final DatagramChannel dc;
        Exception e = null;

        Reactor() throws IOException {
            dc = DatagramChannel.open().bind(new InetSocketAddress(0));
        }

        int port() {
            return dc.socket().getLocalPort();
        }

        public void throwException() throws Exception {
            if (e != null)
                throw e;
        }

        public void run() {
            try {
                // Listen for a message
                ByteBuffer bb = ByteBuffer.allocateDirect(100);
                SocketAddress sa = dc.receive(bb);
                bb.flip();
                CharBuffer cb = Charset.forName("US-ASCII").
                newDecoder().decode(bb);
                log.println("From Actor: "+sa+ " said " +cb);

                // Reply to sender
                dc.connect(sa);
                bb.flip();
                dc.write(bb);

                // Clean up
                dc.disconnect();
                dc.close();
            } catch (Exception ex) {
                e = ex;
            }
        }
    }
}