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class="vp-sidebar-title">系统集成</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">SQL手册</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">FAQ</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-header clickable" type="button"><!----><span class="vp-sidebar-title">附录</span><span class="vp-arrow end"></span></button><!----></section></li></ul><!----></aside><!--[--><main id="main-content" class="vp-page"><!--[--><!----><!----><nav class="vp-breadcrumb disable"></nav><div class="vp-page-title"><h1><!---->MQTT 协议</h1><div class="page-info"><!----><!----><span class="page-date-info" aria-label="写作日期📅" data-balloon-pos="up"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="calendar icon" name="calendar"><path d="M716.4 110.137c0-18.753-14.72-33.473-33.472-33.473-18.753 0-33.473 14.72-33.473 33.473v33.473h66.993v-33.473zm-334.87 0c0-18.753-14.72-33.473-33.473-33.473s-33.52 14.72-33.52 33.473v33.473h66.993v-33.473zm468.81 33.52H716.4v100.465c0 18.753-14.72 33.473-33.472 33.473a33.145 33.145 0 01-33.473-33.473V143.657H381.53v100.465c0 18.753-14.72 33.473-33.473 33.473a33.145 33.145 0 01-33.473-33.473V143.657H180.6A134.314 134.314 0 0046.66 277.595v535.756A134.314 134.314 0 00180.6 947.289h669.74a134.36 134.36 0 00133.94-133.938V277.595a134.314 134.314 0 00-133.94-133.938zm33.473 267.877H147.126a33.145 33.145 0 01-33.473-33.473c0-18.752 14.72-33.473 33.473-33.473h736.687c18.752 0 33.472 14.72 33.472 33.473a33.145 33.145 0 01-33.472 33.473z"></path></svg><span data-allow-mismatch="text">2023年7月10日</span><meta 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145.635 142.01 145.635s142.011-65.374 142.011-145.635c0-8.803 6.99-15.793 15.794-15.793s15.793 6.99 15.793 15.793c0 95.019-73.789 172.82-165.96 177.093z"></path></svg><span>大约 3 分钟</span><meta property="timeRequired" content="PT3M"></span><!----><!----></div><hr></div><div class="vp-toc-placeholder"><aside id="toc" vp-toc><!----><!--[--><div class="vp-toc-header">此页内容<button type="button" class="print-button" title="打印"><svg xmlns="http://www.w3.org/2000/svg" class="icon print-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="print icon" name="print"><path d="M819.2 364.8h-44.8V128c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v236.8h-44.8C145.067 364.8 96 413.867 96 473.6v192c0 59.733 49.067 108.8 108.8 108.8h44.8V896c0 17.067 14.933 32 32 32h460.8c17.067 0 32-14.933 32-32V774.4h44.8c59.733 0 108.8-49.067 108.8-108.8v-192c0-59.733-49.067-108.8-108.8-108.8zM313.6 160h396.8v204.8H313.6V160zm396.8 704H313.6V620.8h396.8V864zM864 665.6c0 25.6-19.2 44.8-44.8 44.8h-44.8V588.8c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v121.6h-44.8c-25.6 0-44.8-19.2-44.8-44.8v-192c0-25.6 19.2-44.8 44.8-44.8h614.4c25.6 0 44.8 19.2 44.8 44.8v192z"></path></svg></button><div class="arrow end"></div></div><div class="vp-toc-wrapper"><ul class="vp-toc-list"><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level2" href="#内置-mqtt-服务">内置 MQTT 服务</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level2" href="#mqtt-配置">MQTT 配置</a></li><!----><!--]--><!--[--><li class="vp-toc-item"><a class="route-link vp-toc-link level2" href="#自定义-mqtt-消息格式">自定义 MQTT 消息格式</a></li><!----><!--]--></ul><div class="vp-toc-marker" style="top:-1.7rem;"></div></div><!--]--><!----></aside></div><!----><div class="theme-hope-content" vp-content><h1 id="mqtt-协议" tabindex="-1"><a class="header-anchor" href="#mqtt-协议"><span>MQTT 协议</span></a></h1><p><a href="http://mqtt.org/" target="_blank" rel="noopener noreferrer">MQTT</a> 是机器对机器（M2M）/“物联网”连接协议。</p><p>它被设计为一种非常轻量级的发布/订阅消息传递。</p><p>对于与需要较小代码占用和/或网络带宽非常宝贵的远程位置的连接很有用。</p><p>IoTDB 支持 MQTT v3.1（OASIS 标准）协议。<br> IoTDB 服务器包括内置的 MQTT 服务，该服务允许远程设备将消息直接发送到 IoTDB 服务器。</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="/img/github/78357432-0c71cf80-75e4-11ea-98aa-c43a54d469ce.png"><h2 id="内置-mqtt-服务" tabindex="-1"><a class="header-anchor" href="#内置-mqtt-服务"><span>内置 MQTT 服务</span></a></h2><p>内置的 MQTT 服务提供了通过 MQTT 直接连接到 IoTDB 的能力。 它侦听来自 MQTT 客户端的发布消息，然后立即将数据写入存储。<br> MQTT 主题与 IoTDB 时间序列相对应。<br> 消息有效载荷可以由 Java SPI 加载的<code>PayloadFormatter</code>格式化为事件，默认实现为<code>JSONPayloadFormatter</code><br> 默认的<code>json</code>格式化程序支持两种 json 格式以及由他们组成的json数组，以下是 MQTT 消息有效负载示例：</p><div class="language-json line-numbers-mode" data-highlighter="shiki" data-ext="json" data-title="json" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code><span class="line"><span style="color:#ABB2BF;"> {</span></span> |
| <span class="line"><span style="color:#E06C75;"> "device"</span><span style="color:#ABB2BF;">:</span><span style="color:#98C379;">"root.sg.d1"</span><span style="color:#ABB2BF;">,</span></span> |
| <span class="line"><span style="color:#E06C75;"> "timestamp"</span><span style="color:#ABB2BF;">:</span><span style="color:#D19A66;">1586076045524</span><span style="color:#ABB2BF;">,</span></span> |
| <span class="line"><span style="color:#E06C75;"> "measurements"</span><span style="color:#ABB2BF;">:[</span><span style="color:#98C379;">"s1"</span><span style="color:#ABB2BF;">,</span><span style="color:#98C379;">"s2"</span><span style="color:#ABB2BF;">],</span></span> |
| <span class="line"><span style="color:#E06C75;"> "values"</span><span style="color:#ABB2BF;">:[</span><span style="color:#D19A66;">0.530635</span><span style="color:#ABB2BF;">,</span><span style="color:#D19A66;">0.530635</span><span style="color:#ABB2BF;">]</span></span> |
| <span class="line"><span style="color:#ABB2BF;"> }</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>或者</p><div class="language-json line-numbers-mode" data-highlighter="shiki" data-ext="json" data-title="json" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code><span class="line"><span style="color:#ABB2BF;"> {</span></span> |
| <span class="line"><span style="color:#E06C75;"> "device"</span><span style="color:#ABB2BF;">:</span><span style="color:#98C379;">"root.sg.d1"</span><span style="color:#ABB2BF;">,</span></span> |
| <span class="line"><span style="color:#E06C75;"> "timestamps"</span><span style="color:#ABB2BF;">:[</span><span style="color:#D19A66;">1586076045524</span><span style="color:#ABB2BF;">,</span><span style="color:#D19A66;">1586076065526</span><span style="color:#ABB2BF;">],</span></span> |
| <span class="line"><span style="color:#E06C75;"> "measurements"</span><span style="color:#ABB2BF;">:[</span><span style="color:#98C379;">"s1"</span><span style="color:#ABB2BF;">,</span><span style="color:#98C379;">"s2"</span><span style="color:#ABB2BF;">],</span></span> |
| <span class="line"><span style="color:#E06C75;"> "values"</span><span style="color:#ABB2BF;">:[[</span><span style="color:#D19A66;">0.530635</span><span style="color:#ABB2BF;">,</span><span style="color:#D19A66;">0.530635</span><span style="color:#ABB2BF;">], [</span><span style="color:#D19A66;">0.530655</span><span style="color:#ABB2BF;">,</span><span style="color:#D19A66;">0.530695</span><span style="color:#ABB2BF;">]]</span></span> |
| <span class="line"><span style="color:#ABB2BF;"> }</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>或者以上两者的JSON数组形式。</p><img style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;" src="/img/github/78357469-1bf11880-75e4-11ea-978f-a53996667a0d.png"><h2 id="mqtt-配置" tabindex="-1"><a class="header-anchor" href="#mqtt-配置"><span>MQTT 配置</span></a></h2><p>默认情况下，IoTDB MQTT 服务从<code>${IOTDB_HOME}/${IOTDB_CONF}/iotdb-common.properties</code>加载配置。</p><p>配置如下：</p><table><thead><tr><th>名称</th><th style="text-align:center;">描述</th><th style="text-align:center;">默认</th></tr></thead><tbody><tr><td>enable_mqtt_service</td><td style="text-align:center;">是否启用 mqtt 服务</td><td style="text-align:center;">false</td></tr><tr><td>mqtt_host</td><td style="text-align:center;">mqtt 服务绑定主机</td><td style="text-align:center;">127.0.0.1</td></tr><tr><td>mqtt_port</td><td style="text-align:center;">mqtt 服务绑定端口</td><td style="text-align:center;">1883</td></tr><tr><td>mqtt_handler_pool_size</td><td style="text-align:center;">处理 mqtt 消息的处理程序池大小</td><td style="text-align:center;">1</td></tr><tr><td>mqtt_payload_formatter</td><td style="text-align:center;">mqtt 消息有效负载格式化程序</td><td style="text-align:center;">json</td></tr><tr><td>mqtt_max_message_size</td><td style="text-align:center;">mqtt 消息最大长度（字节）</td><td style="text-align:center;">1048576</td></tr></tbody></table><p>## 示例代码<br> 以下是 mqtt 客户端将消息发送到 IoTDB 服务器的示例。</p><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" data-title="java" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code><span class="line"><span style="color:#E5C07B;">MQTT</span><span style="color:#E06C75;"> mqtt </span><span style="color:#56B6C2;">=</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> MQTT</span><span style="color:#E06C75;">()</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#E5C07B;">mqtt</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setHost</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"127.0.0.1"</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">1883</span><span style="color:#ABB2BF;">);</span></span> |
| <span class="line"><span style="color:#E5C07B;">mqtt</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setUserName</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"root"</span><span style="color:#ABB2BF;">);</span></span> |
| <span class="line"><span style="color:#E5C07B;">mqtt</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setPassword</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"root"</span><span style="color:#ABB2BF;">);</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#E5C07B;">BlockingConnection</span><span style="color:#E06C75;"> connection </span><span style="color:#56B6C2;">=</span><span style="color:#E5C07B;"> mqtt</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">blockingConnection</span><span style="color:#ABB2BF;">();</span></span> |
| <span class="line"><span style="color:#E5C07B;">connection</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">connect</span><span style="color:#ABB2BF;">();</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#E5C07B;">Random</span><span style="color:#E06C75;"> random </span><span style="color:#56B6C2;">=</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Random</span><span style="color:#E06C75;">()</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#C678DD;">for</span><span style="color:#E06C75;"> (</span><span style="color:#C678DD;">int</span><span style="color:#E06C75;"> i </span><span style="color:#56B6C2;">=</span><span style="color:#D19A66;"> 0</span><span style="color:#ABB2BF;">;</span><span style="color:#E06C75;"> i </span><span style="color:#56B6C2;"><</span><span style="color:#D19A66;"> 10</span><span style="color:#ABB2BF;">;</span><span style="color:#E06C75;"> i</span><span style="color:#ABB2BF;">++</span><span style="color:#E06C75;">) {</span></span> |
| <span class="line"><span style="color:#E5C07B;"> String</span><span style="color:#E06C75;"> payload </span><span style="color:#56B6C2;">=</span><span style="color:#E5C07B;"> String</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">format</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"{</span><span style="color:#56B6C2;">\n</span><span style="color:#98C379;">"</span><span style="color:#56B6C2;"> +</span></span> |
| <span class="line"><span style="color:#98C379;"> "</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">device</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">:</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">root.sg.d1</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">,</span><span style="color:#56B6C2;">\n</span><span style="color:#98C379;">"</span><span style="color:#56B6C2;"> +</span></span> |
| <span class="line"><span style="color:#98C379;"> "</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">timestamp</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">:%d,</span><span style="color:#56B6C2;">\n</span><span style="color:#98C379;">"</span><span style="color:#56B6C2;"> +</span></span> |
| <span class="line"><span style="color:#98C379;"> "</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">measurements</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">:[</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">s1</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">],</span><span style="color:#56B6C2;">\n</span><span style="color:#98C379;">"</span><span style="color:#56B6C2;"> +</span></span> |
| <span class="line"><span style="color:#98C379;"> "</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">values</span><span style="color:#56B6C2;">\"</span><span style="color:#98C379;">:[%f]</span><span style="color:#56B6C2;">\n</span><span style="color:#98C379;">"</span><span style="color:#56B6C2;"> +</span></span> |
| <span class="line"><span style="color:#98C379;"> "}"</span><span style="color:#ABB2BF;">, </span><span style="color:#E5C07B;">System</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">currentTimeMillis</span><span style="color:#ABB2BF;">(), </span><span style="color:#E5C07B;">random</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">nextDouble</span><span style="color:#ABB2BF;">());</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#E5C07B;"> connection</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">publish</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"root.sg.d1.s1"</span><span style="color:#ABB2BF;">, </span><span style="color:#E5C07B;">payload</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">getBytes</span><span style="color:#ABB2BF;">(), </span><span style="color:#E5C07B;">QoS</span><span style="color:#ABB2BF;">.</span><span style="color:#E5C07B;">AT_LEAST_ONCE</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">false</span><span style="color:#ABB2BF;">);</span></span> |
| <span class="line"><span style="color:#E06C75;">}</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#E5C07B;">connection</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">disconnect</span><span style="color:#ABB2BF;">();</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="自定义-mqtt-消息格式" tabindex="-1"><a class="header-anchor" href="#自定义-mqtt-消息格式"><span>自定义 MQTT 消息格式</span></a></h2><p>事实上可以通过简单编程来实现 MQTT 消息的格式自定义。<br> 可以在源码的 <code>example/mqtt-customize</code> 项目中找到一个简单示例。</p><p>步骤:</p><ul><li>创建一个 Java 项目，增加如下依赖</li></ul><div class="language-xml line-numbers-mode" data-highlighter="shiki" data-ext="xml" data-title="xml" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code><span class="line"><span style="color:#ABB2BF;"> <</span><span style="color:#E06C75;">dependency</span><span style="color:#ABB2BF;">></span></span> |
| <span class="line"><span style="color:#ABB2BF;"> <</span><span style="color:#E06C75;">groupId</span><span style="color:#ABB2BF;">>org.apache.iotdb</</span><span style="color:#E06C75;">groupId</span><span style="color:#ABB2BF;">></span></span> |
| <span class="line"><span style="color:#ABB2BF;"> <</span><span style="color:#E06C75;">artifactId</span><span style="color:#ABB2BF;">>iotdb-server</</span><span style="color:#E06C75;">artifactId</span><span style="color:#ABB2BF;">></span></span> |
| <span class="line"><span style="color:#ABB2BF;"> <</span><span style="color:#E06C75;">version</span><span style="color:#ABB2BF;">>1.3.0-SNAPSHOT</</span><span style="color:#E06C75;">version</span><span style="color:#ABB2BF;">></span></span> |
| <span class="line"><span style="color:#ABB2BF;"> </</span><span style="color:#E06C75;">dependency</span><span style="color:#ABB2BF;">></span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><ul><li>创建一个实现类，实现接口 <code>org.apache.iotdb.db.mqtt.protocol.PayloadFormatter</code></li></ul><div class="language-java line-numbers-mode" data-highlighter="shiki" data-ext="java" data-title="java" style="background-color:#282c34;color:#abb2bf;"><pre class="shiki one-dark-pro vp-code"><code><span class="line"><span style="color:#C678DD;">package</span><span style="color:#C678DD;"> org.apache.iotdb.mqtt.server</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> io.netty.buffer.ByteBuf</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> org.apache.iotdb.db.protocol.mqtt.Message</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> org.apache.iotdb.db.protocol.mqtt.PayloadFormatter</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> java.nio.charset.StandardCharsets</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> java.util.ArrayList</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> java.util.Arrays</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#C678DD;">import</span><span style="color:#E5C07B;"> java.util.List</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#C678DD;">public</span><span style="color:#C678DD;"> class</span><span style="color:#E5C07B;"> CustomizedJsonPayloadFormatter</span><span style="color:#C678DD;"> implements</span><span style="color:#E5C07B;"> PayloadFormatter</span><span style="color:#ABB2BF;"> {</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#ABB2BF;"> @</span><span style="color:#E5C07B;">Override</span></span> |
| <span class="line"><span style="color:#C678DD;"> public</span><span style="color:#E5C07B;"> List</span><span style="color:#ABB2BF;"><</span><span style="color:#E5C07B;">Message</span><span style="color:#ABB2BF;">></span><span style="color:#61AFEF;"> format</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">ByteBuf</span><span style="color:#E06C75;font-style:italic;"> payload</span><span style="color:#ABB2BF;">)</span><span style="color:#ABB2BF;"> {</span></span> |
| <span class="line"><span style="color:#7F848E;font-style:italic;"> // Suppose the payload is a json format</span></span> |
| <span class="line"><span style="color:#C678DD;"> if</span><span style="color:#ABB2BF;"> (payload </span><span style="color:#56B6C2;">==</span><span style="color:#D19A66;"> null</span><span style="color:#ABB2BF;">) {</span></span> |
| <span class="line"><span style="color:#C678DD;"> return</span><span style="color:#D19A66;"> null</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#ABB2BF;"> }</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#E5C07B;"> String</span><span style="color:#E06C75;"> json</span><span style="color:#56B6C2;"> =</span><span style="color:#E5C07B;"> payload</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">toString</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">StandardCharsets</span><span style="color:#ABB2BF;">.</span><span style="color:#E5C07B;">UTF_8</span><span style="color:#ABB2BF;">);</span></span> |
| <span class="line"><span style="color:#7F848E;font-style:italic;"> // parse data from the json and generate Messages and put them into List<Meesage> ret</span></span> |
| <span class="line"><span style="color:#E5C07B;"> List</span><span style="color:#ABB2BF;"><</span><span style="color:#E5C07B;">Message</span><span style="color:#ABB2BF;">> </span><span style="color:#E06C75;">ret</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#E5C07B;"> ArrayList</span><span style="color:#ABB2BF;"><>();</span></span> |
| <span class="line"><span style="color:#7F848E;font-style:italic;"> // this is just an example, so we just generate some Messages directly</span></span> |
| <span class="line"><span style="color:#C678DD;"> for</span><span style="color:#ABB2BF;"> (</span><span style="color:#C678DD;">int</span><span style="color:#E06C75;"> i</span><span style="color:#56B6C2;"> =</span><span style="color:#D19A66;"> 0</span><span style="color:#ABB2BF;">; i </span><span style="color:#56B6C2;"><</span><span style="color:#D19A66;"> 2</span><span style="color:#ABB2BF;">; i++) {</span></span> |
| <span class="line"><span style="color:#C678DD;"> long</span><span style="color:#E06C75;"> ts</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> i;</span></span> |
| <span class="line"><span style="color:#E5C07B;"> Message</span><span style="color:#E06C75;"> message</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Message</span><span style="color:#ABB2BF;">();</span></span> |
| <span class="line"><span style="color:#E5C07B;"> message</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setDevice</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"d"</span><span style="color:#56B6C2;"> +</span><span style="color:#ABB2BF;"> i);</span></span> |
| <span class="line"><span style="color:#E5C07B;"> message</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setTimestamp</span><span style="color:#ABB2BF;">(ts);</span></span> |
| <span class="line"><span style="color:#E5C07B;"> message</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setMeasurements</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">Arrays</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">asList</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"s1"</span><span style="color:#ABB2BF;">, </span><span style="color:#98C379;">"s2"</span><span style="color:#ABB2BF;">));</span></span> |
| <span class="line"><span style="color:#E5C07B;"> message</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">setValues</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">Arrays</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">asList</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">"4.0"</span><span style="color:#56B6C2;"> +</span><span style="color:#ABB2BF;"> i, </span><span style="color:#98C379;">"5.0"</span><span style="color:#56B6C2;"> +</span><span style="color:#ABB2BF;"> i));</span></span> |
| <span class="line"><span style="color:#E5C07B;"> ret</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">add</span><span style="color:#ABB2BF;">(message);</span></span> |
| <span class="line"><span style="color:#ABB2BF;"> }</span></span> |
| <span class="line"><span style="color:#C678DD;"> return</span><span style="color:#ABB2BF;"> ret;</span></span> |
| <span class="line"><span style="color:#ABB2BF;"> }</span></span> |
| <span class="line"></span> |
| <span class="line"><span style="color:#ABB2BF;"> @</span><span style="color:#E5C07B;">Override</span></span> |
| <span class="line"><span style="color:#C678DD;"> public</span><span style="color:#E5C07B;"> String</span><span style="color:#61AFEF;"> getName</span><span style="color:#ABB2BF;">()</span><span style="color:#ABB2BF;"> {</span></span> |
| <span class="line"><span style="color:#7F848E;font-style:italic;"> // set the value of mqtt_payload_formatter in iotdb-common.properties as the following string:</span></span> |
| <span class="line"><span style="color:#C678DD;"> return</span><span style="color:#98C379;"> "CustomizedJson"</span><span style="color:#ABB2BF;">;</span></span> |
| <span class="line"><span style="color:#ABB2BF;"> }</span></span> |
| <span class="line"><span style="color:#ABB2BF;">}</span></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><ul><li>修改项目中的 <code>src/main/resources/META-INF/services/org.apache.iotdb.db.protocol.mqtt.PayloadFormatter</code> 文件:<br> 将示例中的文件内容清除，并将刚才的实现类的全名（包名.类名）写入文件中。注意，这个文件中只有一行。<br> 在本例中，文件内容为: <code>org.apache.iotdb.mqtt.server.CustomizedJsonPayloadFormatter</code></li><li>编译项目生成一个 jar 包: <code>mvn package -DskipTests</code></li></ul><p>在 IoTDB 服务端:</p><ul><li>创建 ${IOTDB_HOME}/ext/mqtt/ 文件夹, 将刚才的 jar 包放入此文件夹。</li><li>打开 MQTT 服务参数. (<code>enable_mqtt_service=true</code> in <code>conf/iotdb-common.properties</code>)</li><li>用刚才的实现类中的 getName() 方法的返回值 设置为 <code>conf/iotdb-common.properties</code> 中 <code>mqtt_payload_formatter</code> 的值，<br> , 在本例中，为 <code>CustomizedJson</code></li><li>启动 IoTDB</li><li>搞定.</li></ul><p>More: MQTT 协议的消息不限于 json，你还可以用任意二进制。通过如下函数获得：<br><code>payload.forEachByte()</code> or <code>payload.array</code>。</p></div><!----><footer class="vp-page-meta"><div class="vp-meta-item edit-link"><a class="auto-link external-link vp-meta-label" href="https://github.com/apache/iotdb-docs/edit/main/src/zh/UserGuide/V1.2.x/API/Programming-MQTT.md" aria-label="发现错误？在 GitHub 上编辑此页" rel="noopener noreferrer" target="_blank" iconsizing="both"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon" name="edit"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></svg><!--]-->发现错误？在 GitHub 上编辑此页<!----></a></div><div class="vp-meta-item git-info"><div class="update-time"><span class="vp-meta-label">上次编辑于: </span><span class="vp-meta-info" data-allow-mismatch="text">2025/2/14 07:03:32</span></div><!----></div></footer><nav class="vp-page-nav"><a class="route-link auto-link prev" href="/zh/UserGuide/V1.2.x/API/Programming-JDBC.html" aria-label="JDBC (不推荐)" iconsizing="both"><div class="hint"><span class="arrow start"></span>上一页</div><div class="link"><!---->JDBC (不推荐)</div></a><a class="route-link auto-link next" href="/zh/UserGuide/V1.2.x/API/Programming-Kafka.html" aria-label="Kafka" iconsizing="both"><div class="hint">下一页<span class="arrow end"></span></div><div class="link">Kafka<!----></div></a></nav><!----><!----><!--]--></main><!--]--><footer class="site-footer"><span id="doc-version" style="display:none;">V1.2.x</span><p class="copyright-text">版权所有 © 2025 Apache软件基金会。 |
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