MqttVersion Type — netty Architecture

Source Code

codec-mqtt/src/main/java/io/netty/handler/codec/mqtt/MqttVersion.java lines 25–70

public enum MqttVersion {
    MQTT_3_1("MQIsdp", (byte) 3),
    MQTT_3_1_1("MQTT", (byte) 4),
    MQTT_5("MQTT", (byte) 5);

    private final String name;
    private final byte level;

    MqttVersion(String protocolName, byte protocolLevel) {
        name = ObjectUtil.checkNotNull(protocolName, "protocolName");
        level = protocolLevel;
    }

    public String protocolName() {
        return name;
    }

    public byte[] protocolNameBytes() {
        return name.getBytes(CharsetUtil.UTF_8);
    }

    public byte protocolLevel() {
        return level;
    }

    public static MqttVersion fromProtocolNameAndLevel(String protocolName, byte protocolLevel) {
        MqttVersion mv;
        switch (protocolLevel) {
        case 3:
            mv = MQTT_3_1;
            break;
        case 4:
            mv = MQTT_3_1_1;
            break;
        case 5:
            mv = MQTT_5;
            break;
        default:
            throw new MqttUnacceptableProtocolVersionException(protocolName + " is an unknown protocol name");
        }
        if (mv.name.equals(protocolName)) {
            return mv;
        }
        throw new MqttUnacceptableProtocolVersionException(protocolName + " and " + protocolLevel + " don't match");
    }
}