Java example source code file (Sender.java)

This example Java source code file (Sender.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

bytebuffer, client, datagramchannel, exception, inetaddress, inetsocketaddress, ioexception, net, network, nio, printstream, runnable, runtimeexception, sender, server, test, thread

The Sender.java Java example source code

/*
 * Copyright (c) 2002, 2010, 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 4669040
 * @summary Test DatagramChannel subsequent receives with no datagram ready
 * @author Mike McCloskey
 */

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

public class Sender {

    static PrintStream log = System.err;

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

    static void test() throws Exception {
        Server server = new Server();
        Client client = new Client(server.port());

        Thread serverThread = new Thread(server);
        serverThread.start();

        Thread clientThread = new Thread(client);
        clientThread.start();

        serverThread.join();
        clientThread.join();

        server.throwException();
        client.throwException();
    }

    public static class Client implements Runnable {
        final int port;
        Exception e = null;

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

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

        public void run() {
            try {
                DatagramChannel dc = DatagramChannel.open();
                ByteBuffer bb = ByteBuffer.allocateDirect(12);
                bb.order(ByteOrder.BIG_ENDIAN);
                bb.putInt(1).putLong(1);
                bb.flip();
                InetAddress address = InetAddress.getLocalHost();
                InetSocketAddress isa = new InetSocketAddress(address, port);
                dc.connect(isa);
                dc.write(bb);
            } catch (Exception ex) {
                e = ex;
            }
        }
    }

    public static class Server implements Runnable {
        final DatagramChannel dc;
        Exception e = null;

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

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

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

        void showBuffer(String s, ByteBuffer bb) {
            log.println(s);
            bb.rewind();
            for (int i=0; i<bb.limit(); i++) {
                byte element = bb.get();
                log.print(element);
            }
            log.println();
        }

        public void run() {
            SocketAddress sa = null;

            try {
                ByteBuffer bb = ByteBuffer.allocateDirect(12);
                bb.clear();
                // Get the one valid datagram
                dc.configureBlocking(false);
                while (sa == null)
                    sa = dc.receive(bb);
                sa = null;
                for (int i=0; i<100; i++) {
                    bb.clear();
                    sa = dc.receive(bb);
                    if (sa != null)
                        throw new RuntimeException("Test failed");
                }
                dc.close();
            } catch (Exception ex) {
                e = ex;
            }
        }
    }

}