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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.internal.SocketUtils;
29  
30  import java.util.concurrent.TimeUnit;
31  
32  import static java.nio.charset.StandardCharsets.UTF_8;
33  
34  /**
35   * A UDP broadcast client that asks for a quote of the moment (QOTM) to {@link QuoteOfTheMomentServer}.
36   *
37   * Inspired by <a href="https://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html">the official
38   * Java tutorial</a>.
39   */
40  public final class QuoteOfTheMomentClient {
41  
42      static final int PORT = Integer.parseInt(System.getProperty("port", "7686"));
43  
44      public static void main(String[] args) throws Exception {
45  
46          EventLoopGroup group = new MultithreadEventLoopGroup(NioHandler.newFactory());
47          try {
48              Bootstrap b = new Bootstrap();
49              b.group(group)
50               .channel(NioDatagramChannel.class)
51               .option(ChannelOption.SO_BROADCAST, true)
52               .handler(new QuoteOfTheMomentClientHandler());
53  
54              Channel ch = b.bind(0).asStage().get();
55  
56              // Broadcast the QOTM request to port 8080.
57              Buffer message = DefaultBufferAllocators.preferredAllocator().copyOf("QOTM?", UTF_8);
58              ch.writeAndFlush(new DatagramPacket(message, SocketUtils.socketAddress("255.255.255.255", PORT)))
59                .asStage().sync();
60  
61              // QuoteOfTheMomentClientHandler will close the DatagramChannel when a
62              // response is received.  If the channel is not closed within 5 seconds,
63              // print an error message and quit.
64              if (!ch.closeFuture().asStage().await(5000, TimeUnit.MILLISECONDS)) {
65                  System.err.println("QOTM request timed out.");
66              }
67          } finally {
68              group.shutdownGracefully();
69          }
70      }
71  }