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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.CharsetUtil;
20  import io.netty.util.internal.ObjectUtil;
21  
22  /**
23   * Mqtt version specific constant values used by multiple classes in mqtt-codec.
24   */
25  public enum MqttVersion {
26      MQTT_3_1("MQIsdp", (byte) 3),
27      MQTT_3_1_1("MQTT", (byte) 4);
28  
29      private final String name;
30      private final byte level;
31  
32      MqttVersion(String protocolName, byte protocolLevel) {
33          name = ObjectUtil.checkNotNull(protocolName, "protocolName");
34          level = protocolLevel;
35      }
36  
37      public String protocolName() {
38          return name;
39      }
40  
41      public byte[] protocolNameBytes() {
42          return name.getBytes(CharsetUtil.UTF_8);
43      }
44  
45      public byte protocolLevel() {
46          return level;
47      }
48  
49      public static MqttVersion fromProtocolNameAndLevel(String protocolName, byte protocolLevel) {
50          for (MqttVersion mv : values()) {
51              if (mv.name.equals(protocolName)) {
52                  if (mv.level == protocolLevel) {
53                      return mv;
54                  } else {
55                      throw new MqttUnacceptableProtocolVersionException(protocolName + " and " +
56                              protocolLevel + " are not match");
57                  }
58              }
59          }
60          throw new MqttUnacceptableProtocolVersionException(protocolName + "is unknown protocol name");
61      }
62  }