11255c6602
Motivation:
Currently, the only way to create fixed-header only messages PINGREQ,
PINGRESP and DISCONNECT is to explicitly instantiate a `MqttFixedHeader` like:
```
MqttFixedHeader disconnectFixedHeader = new MqttFixedHeader(MqttMessageType.DISCONNECT,
false, MqttQoS.AT_MOST_ONCE, false, 0);
MqttMessage disconnectMessage = new MqttMessage(disconnectFixedHeader);
```
According to the MQTT spec
(http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718077),
the fixed-header flags for these messages are reserved and must be set to zero, otherwise
the receiver must close the connection. It's easy to mess this up when
you're creating the header explicitly, for e.g by setting the QoS bit to
`AT_LEAST_ONCE`.
As such, provide static constants for PINGREQ, PINGRESP and
DISCONNECT messages that will set the flags correctly for the developer.
Modification:
Add static constants to MqttMessage class to construct PINGREQ, PINGRESP and
DISCONNECT messages that will set the fixed-header flags correctly to 0.
Result:
Easier usage.
93 lines
3.2 KiB
Java
93 lines
3.2 KiB
Java
/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.mqtt;
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import io.netty.handler.codec.DecoderResult;
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import io.netty.util.internal.StringUtil;
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/**
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* Base class for all MQTT message types.
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*/
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public class MqttMessage {
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private final MqttFixedHeader mqttFixedHeader;
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private final Object variableHeader;
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private final Object payload;
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private final DecoderResult decoderResult;
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// Constants for fixed-header only message types with all flags set to 0 (see
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// http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Table_2.2_-)
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public static final MqttMessage PINGREQ = new MqttMessage(new MqttFixedHeader(MqttMessageType.PINGREQ, false,
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MqttQoS.AT_MOST_ONCE, false, 0));
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public static final MqttMessage PINGRESP = new MqttMessage(new MqttFixedHeader(MqttMessageType.PINGRESP, false,
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MqttQoS.AT_MOST_ONCE, false, 0));
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public static final MqttMessage DISCONNECT = new MqttMessage(new MqttFixedHeader(MqttMessageType.DISCONNECT, false,
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MqttQoS.AT_MOST_ONCE, false, 0));
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public MqttMessage(MqttFixedHeader mqttFixedHeader) {
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this(mqttFixedHeader, null, null);
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}
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public MqttMessage(MqttFixedHeader mqttFixedHeader, Object variableHeader) {
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this(mqttFixedHeader, variableHeader, null);
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}
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public MqttMessage(MqttFixedHeader mqttFixedHeader, Object variableHeader, Object payload) {
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this(mqttFixedHeader, variableHeader, payload, DecoderResult.SUCCESS);
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}
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public MqttMessage(
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MqttFixedHeader mqttFixedHeader,
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Object variableHeader,
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Object payload,
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DecoderResult decoderResult) {
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this.mqttFixedHeader = mqttFixedHeader;
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this.variableHeader = variableHeader;
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this.payload = payload;
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this.decoderResult = decoderResult;
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}
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public MqttFixedHeader fixedHeader() {
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return mqttFixedHeader;
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}
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public Object variableHeader() {
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return variableHeader;
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}
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public Object payload() {
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return payload;
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}
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public DecoderResult decoderResult() {
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return decoderResult;
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}
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@Override
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public String toString() {
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return new StringBuilder(StringUtil.simpleClassName(this))
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.append('[')
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.append("fixedHeader=").append(fixedHeader() != null ? fixedHeader().toString() : "")
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.append(", variableHeader=").append(variableHeader() != null ? variableHeader.toString() : "")
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.append(", payload=").append(payload() != null ? payload.toString() : "")
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.append(']')
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.toString();
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}
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}
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