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