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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.example.qotm;
17  
18  import io.netty.bootstrap.Bootstrap;
19  import io.netty.buffer.Unpooled;
20  import io.netty.channel.Channel;
21  import io.netty.channel.ChannelOption;
22  import io.netty.channel.EventLoopGroup;
23  import io.netty.channel.nio.NioEventLoopGroup;
24  import io.netty.channel.socket.DatagramPacket;
25  import io.netty.channel.socket.nio.NioDatagramChannel;
26  import io.netty.util.CharsetUtil;
27  
28  import java.net.InetSocketAddress;
29  
30  /**
31   * A UDP broadcast client that asks for a quote of the moment (QOTM) to {@link QuoteOfTheMomentServer}.
32   *
33   * Inspired by <a href="http://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html">the official
34   * Java tutorial</a>.
35   */
36  public final class QuoteOfTheMomentClient {
37  
38      static final int PORT = Integer.parseInt(System.getProperty("port", "7686"));
39  
40      public static void main(String[] args) throws Exception {
41  
42          EventLoopGroup group = new NioEventLoopGroup();
43          try {
44              Bootstrap b = new Bootstrap();
45              b.group(group)
46               .channel(NioDatagramChannel.class)
47               .option(ChannelOption.SO_BROADCAST, true)
48               .handler(new QuoteOfTheMomentClientHandler());
49  
50              Channel ch = b.bind(0).sync().channel();
51  
52              // Broadcast the QOTM request to port 8080.
53              ch.writeAndFlush(new DatagramPacket(
54                      Unpooled.copiedBuffer("QOTM?", CharsetUtil.UTF_8),
55                      new InetSocketAddress("255.255.255.255", PORT))).sync();
56  
57              // QuoteOfTheMomentClientHandler will close the DatagramChannel when a
58              // response is received.  If the channel is not closed within 5 seconds,
59              // print an error message and quit.
60              if (!ch.closeFuture().await(5000)) {
61                  System.err.println("QOTM request timed out.");
62              }
63          } finally {
64              group.shutdownGracefully();
65          }
66      }
67  }