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1   /*
2    * Copyright 2014 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.stomp;
17  
18  import io.netty.channel.ChannelHandlerContext;
19  import io.netty.channel.SimpleChannelInboundHandler;
20  import io.netty.handler.codec.stomp.DefaultStompFrame;
21  import io.netty.handler.codec.stomp.StompCommand;
22  import io.netty.handler.codec.stomp.StompFrame;
23  import io.netty.handler.codec.stomp.StompHeaders;
24  
25  /**
26   * STOMP client inbound handler implementation, which just passes received messages to listener
27   */
28  public class StompClientHandler extends SimpleChannelInboundHandler<StompFrame> {
29  
30      private enum ClientState {
31          AUTHENTICATING,
32          AUTHENTICATED,
33          SUBSCRIBED,
34          DISCONNECTING
35      }
36  
37      private ClientState state;
38  
39      @Override
40      public void channelActive(ChannelHandlerContext ctx) throws Exception {
41          state = ClientState.AUTHENTICATING;
42          StompFrame connFrame = new DefaultStompFrame(StompCommand.CONNECT);
43          connFrame.headers().set(StompHeaders.ACCEPT_VERSION, "1.2");
44          connFrame.headers().set(StompHeaders.HOST, StompClient.HOST);
45          connFrame.headers().set(StompHeaders.LOGIN, StompClient.LOGIN);
46          connFrame.headers().set(StompHeaders.PASSCODE, StompClient.PASSCODE);
47          ctx.writeAndFlush(connFrame);
48      }
49  
50      @Override
51      protected void channelRead0(ChannelHandlerContext ctx, StompFrame frame) throws Exception {
52          String subscrReceiptId = "001";
53          String disconReceiptId = "002";
54          switch (frame.command()) {
55              case CONNECTED:
56                  StompFrame subscribeFrame = new DefaultStompFrame(StompCommand.SUBSCRIBE);
57                  subscribeFrame.headers().set(StompHeaders.DESTINATION, StompClient.TOPIC);
58                  subscribeFrame.headers().set(StompHeaders.RECEIPT, subscrReceiptId);
59                  subscribeFrame.headers().set(StompHeaders.ID, "1");
60                  System.out.println("connected, sending subscribe frame: " + subscribeFrame);
61                  state = ClientState.AUTHENTICATED;
62                  ctx.writeAndFlush(subscribeFrame);
63                  break;
64              case RECEIPT:
65                  String receiptHeader = frame.headers().getAsString(StompHeaders.RECEIPT_ID);
66                  if (state == ClientState.AUTHENTICATED && receiptHeader.equals(subscrReceiptId)) {
67                      StompFrame msgFrame = new DefaultStompFrame(StompCommand.SEND);
68                      msgFrame.headers().set(StompHeaders.DESTINATION, StompClient.TOPIC);
69                      msgFrame.content().writeBytes("some payload".getBytes());
70                      System.out.println("subscribed, sending message frame: " + msgFrame);
71                      state = ClientState.SUBSCRIBED;
72                      ctx.writeAndFlush(msgFrame);
73                  } else if (state == ClientState.DISCONNECTING && receiptHeader.equals(disconReceiptId)) {
74                      System.out.println("disconnected");
75                      ctx.close();
76                  } else {
77                      throw new IllegalStateException("received: " + frame + ", while internal state is " + state);
78                  }
79                  break;
80              case MESSAGE:
81                  if (state == ClientState.SUBSCRIBED) {
82                      System.out.println("received frame: " + frame);
83                      StompFrame disconnFrame = new DefaultStompFrame(StompCommand.DISCONNECT);
84                      disconnFrame.headers().set(StompHeaders.RECEIPT, disconReceiptId);
85                      System.out.println("sending disconnect frame: " + disconnFrame);
86                      state = ClientState.DISCONNECTING;
87                      ctx.writeAndFlush(disconnFrame);
88                  }
89                  break;
90              default:
91                  break;
92          }
93      }
94  
95      @Override
96      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
97          cause.printStackTrace();
98          ctx.close();
99      }
100 }