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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  
17  package io.netty.handler.codec.mqtt;
18  
19  import io.netty.util.internal.StringUtil;
20  
21  /**
22   * Variable Header containing only Message Id
23   * See <a href="http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html#msg-id">MQTTV3.1/msg-id</a>
24   */
25  public final class MqttMessageIdVariableHeader {
26  
27      private final int messageId;
28  
29      public static MqttMessageIdVariableHeader from(int messageId) {
30        if (messageId < 1 || messageId > 0xffff) {
31          throw new IllegalArgumentException("messageId: " + messageId + " (expected: 1 ~ 65535)");
32        }
33        return new MqttMessageIdVariableHeader(messageId);
34      }
35  
36      private MqttMessageIdVariableHeader(int messageId) {
37          this.messageId = messageId;
38      }
39  
40      public int messageId() {
41          return messageId;
42      }
43  
44      @Override
45      public String toString() {
46          return new StringBuilder(StringUtil.simpleClassName(this))
47              .append('[')
48              .append("messageId=").append(messageId)
49              .append(']')
50              .toString();
51      }
52  }