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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    *   https://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.netty5.example.qotm;
17  
18  import io.netty5.bootstrap.Bootstrap;
19  import io.netty5.buffer.api.Buffer;
20  import io.netty5.buffer.api.DefaultBufferAllocators;
21  import io.netty5.channel.Channel;
22  import io.netty5.channel.ChannelOption;
23  import io.netty5.channel.EventLoopGroup;
24  import io.netty5.channel.MultithreadEventLoopGroup;
25  import io.netty5.channel.nio.NioHandler;
26  import io.netty5.channel.socket.DatagramPacket;
27  import io.netty5.channel.socket.nio.NioDatagramChannel;
28  import io.netty5.util.CharsetUtil;
29  import io.netty5.util.internal.SocketUtils;
30  
31  /**
32   * A UDP broadcast client that asks for a quote of the moment (QOTM) to {@link QuoteOfTheMomentServer}.
33   *
34   * Inspired by <a href="https://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html">the official
35   * Java tutorial</a>.
36   */
37  public final class QuoteOfTheMomentClient {
38  
39      static final int PORT = Integer.parseInt(System.getProperty("port", "7686"));
40  
41      public static void main(String[] args) throws Exception {
42  
43          EventLoopGroup group = new MultithreadEventLoopGroup(NioHandler.newFactory());
44          try {
45              Bootstrap b = new Bootstrap();
46              b.group(group)
47               .channel(NioDatagramChannel.class)
48               .option(ChannelOption.SO_BROADCAST, true)
49               .handler(new QuoteOfTheMomentClientHandler());
50  
51              Channel ch = b.bind(0).get();
52  
53              // Broadcast the QOTM request to port 8080.
54              Buffer message = DefaultBufferAllocators.preferredAllocator().copyOf("QOTM?".getBytes(CharsetUtil.UTF_8));
55              ch.writeAndFlush(new DatagramPacket(message, SocketUtils.socketAddress("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  }