本文主要是介绍Vert.x框架实现MQTT服务，代码实现及其详解，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
简单的总结
先做一个简单的近日总结吧
最近在学习怎么用vertx框架实现一个mqtt服务和物联网平台进一步的搭建
这两天又折腾了笔记软件，想从语雀迁到obsidian，也花了不少时间，想着最近都没怎么写过博客，就写一写自己这几天学习vertx框架实现mqtt服务的收获和学习到东西
Vert.x MQTT
MQTT是基于发布/订阅(publish/subscribe)模式的”轻量级“通信协议，该协议构建于TCP/IP协议之上，由于其低开销，低带宽占用的特点，非常适合在物联网设备通信方面使用。
关于MQTT相关的基础知识我不再赘述，如果还不清楚的同学可以看看这个文档，快速了解一下相关知识。MQTT 协议入门：基础知识和快速教程
而Vert.x MQTT是一个使用Vert.x实现MQTT协议中客户端与服务端的组件，里边有一些基础的api，可以利用api写出自己想要的服务。以下是其官方文档，可以参考一下，虽然是汉化过的文档，但是我看的过程还是比较困难，可能是作者太菜了。Vert.x MQTT
这里我只用了Vertx MQTT的服务端组件实现了MQTT服务，客户端部分采用了MQTTX创建虚拟设备。MQTTX是一款客户端工具，可以用于创建虚拟设备快速进行测试，MQTT 客户端工具演示 | EMQX 文档
代码实现
先分方法放出来，最后再放完整代码
start()方法
代码的入口，创建了一个MQTT服务器并进行了监听。在接收到来自客户端的连接请求时，会调用不同的处理方法来处理订阅、退订、收到消息和断开连接等操作。
@Overridepublic void start() throws Exception {MqttServer mqttServer = MqttServer.create(vertx);topicSubscribers = new HashMap<>();subscriptions=new HashMap<>();mqttServer.endpointHandler(endpoint -> {//使用lambda表达式实现了endpointHandler方法，传入参数endpoint；System.out.println("MQTT client [" + endpoint.clientIdentifier() + "] request to connect, clean session = " + endpoint.isCleanSession());if (endpoint.auth() != null) {System.out.println("[username = " + endpoint.auth().getUsername() + ", password = " + endpoint.auth().getPassword() + "]");}System.out.println("[properties = " + endpoint.connectProperties() + "]");// accept connection from the remote clientendpoint.accept(false);SubscribeHandle(endpoint);UnSubscribeHandle(endpoint);ReceiveHandle(endpoint);DisConnectHandle(endpoint);});mqttServer.listen(ar -> {if (ar.succeeded()) {System.out.println("MQTT server is listening on port " + ar.result().actualPort());} else {System.out.println("Error on starting the server");ar.cause().printStackTrace();}});}
DisConnectHandle方法
用于处理设备断开连接的情况。当设备发送断开连接消息时，会从订阅关系列表中删除该设备，并从订阅列表中删除该设备的所有订阅。
private void DisConnectHandle(MqttEndpoint endpoint) {endpoint.disconnectMessageHandler(disconnectMessage -> {System.out.println("Received disconnect from client, reason code = " + disconnectMessage.code());System.out.println("Client "+endpoint.auth().getUsername()+"disconnect with");//对两个映射订阅关系的列表进行更新for (String topic:subscriptions.get(endpoint)){topicSubscribers.get(topic).remove(endpoint);System.out.println("["+topic+"]");}subscriptions.remove(endpoint);});}
SubscribeHandle方法
用于处理订阅消息。当设备发送订阅消息时，会检查订阅的主题是否合法。如果主题合法，则将设备添加到订阅关系列表和订阅列表中，并向设备发送订阅确认消息。
private void SubscribeHandle(MqttEndpoint endpoint) {endpoint.subscribeHandler(subscribe -> {Boolean IsValidTopic=false;//存储订阅消息中要订阅的topic的列表List<MqttTopicSubscription> topicSubscriptions = subscribe.topicSubscriptions();//存储订阅topic Qos级别的列表List<MqttSubAckReasonCode> reasonCodes = new ArrayList<>();//遍历列表for (MqttTopicSubscription s : topicSubscriptions) {//topicString topic = s.topicName();//Qos级别MqttQoS qos = s.qualityOfService();//判断topic是否合法if (!isValidTopic(topic)){//不合法则向设备发送消息endpoint.publish(topic, Buffer.buffer("非法topic，topic不可包含空格"), qos, false, false);continue;}else {IsValidTopic=true;}System.out.println("Subscription for " + topic + " with QoS " + qos);reasonCodes.add(MqttSubAckReasonCode.qosGranted(qos));//判断是否已有此topic，如果有则直接添加，没有则新建键值对if (!topicSubscribers.containsKey(topic)) {topicSubscribers.put(topic, new ArrayList<MqttEndpoint>());}topicSubscribers.get(topic).add(endpoint);//同上if (!subscriptions.containsKey(endpoint)) {subscriptions.put(endpoint, new ArrayList<String>());}subscriptions.get(endpoint).add(topic);}if(IsValidTopic){endpoint.subscribeAcknowledge(subscribe.messageId(), reasonCodes, MqttProperties.NO_PROPERTIES);}});}
UnSubscribeHandle方法
用于处理退订消息。当设备发送退订消息时，会从订阅关系列表中删除该设备，并检查是否需要删除订阅列表中的主题。
private void UnSubscribeHandle(MqttEndpoint endpoint) {endpoint.unsubscribeHandler(unsubscribe -> {//遍历要退订的topicfor (String unsubscribedTopic : unsubscribe.topics()) {topicSubscribers.get(unsubscribedTopic).remove(endpoint);//如果某topic的订阅列表为空，删除topicif (topicSubscribers.get(unsubscribedTopic).size() == 0) {topicSubscribers.remove(unsubscribedTopic);}subscriptions.get(endpoint).remove(unsubscribedTopic);//同上if (subscriptions.get(endpoint).size()==0){subscriptions.remove(endpoint);}System.out.println("unsubscribed :" + endpoint.auth().getUsername() + "for" + unsubscribedTopic);}endpoint.unsubscribeAcknowledge(unsubscribe.messageId());});}
ReceiveHandle方法
用于处理收到的消息。当设备发布消息时，会检查发布的主题是否合法。如果主题合法，则遍历订阅关系列表，将消息发布给订阅了匹配主题的设备。
private void ReceiveHandle(MqttEndpoint endpoint) {endpoint.publishHandler(publish -> {String topic = publish.topicName();Buffer payload = publish.payload();//对topic的合法性进行判断if (!isValidTopic(topic)){endpoint.publish(topic, Buffer.buffer("非法topic，topic不可包含空格"), MqttQoS.AT_MOST_ONCE, false, false);return;}//记录日志接收到设备发布的消息System.out.println("Received message [" + publish.payload().toString(Charset.defaultCharset()) + "] with QoS [" + publish.qosLevel() + "]");if (publish.qosLevel() == MqttQoS.AT_LEAST_ONCE) {endpoint.publishAcknowledge(publish.messageId());} else if (publish.qosLevel() == MqttQoS.EXACTLY_ONCE) {endpoint.publishReceived(publish.messageId());}//遍历订阅关系，进行消息发布for (Map.Entry<String, List<MqttEndpoint>> entry : topicSubscribers.entrySet()) {String subscribedTopic = entry.getKey();//被订阅的topicList<MqttEndpoint> subscribers = entry.getValue();//订阅上方topic的订阅者//判断消息发布的topic是否能和被设备订阅的topic按照规则匹配if (isTopicMatch(subscribedTopic, topic)) {//若匹配，则遍历topic订阅者列表，并进行消息发布for (MqttEndpoint subscriber : subscribers) {subscriber.publish(topic, payload, publish.qosLevel(), publish.isDup(), publish.isRetain());}}}});endpoint.publishAcknowledgeHandler(messageId -> {System.out.println("received ack for message =" + messageId);}).publishReceivedHandler(messageId -> {endpoint.publishRelease(messageId);}).publishCompletionHandler(messageId -> {System.out.println("Received ack for message =" + messageId);});endpoint.publishReleaseHandler(endpoint::publishComplete);}
isTopicMatch方法
用于判断订阅的主题和发布的主题是否匹配。它会将主题按照"/“进行分割，并进行逐层匹配，支持通配符”+“和”#"。
private boolean isTopicMatch(String subscribedTopic, String publishedTopic) {String[] publishTopicArray = publishedTopic.split("/");String[] subscribedTopicArray = subscribedTopic.split("/");//将两个要比较的topic分割//订阅的topic长度不能比发布的topic长一个以上if (subscribedTopicArray.length - 1 > publishTopicArray.length) {return false;}//如果发布的topic长度比订阅的topic长度要长//并且订阅的topic最后不是以#结尾都返回false，因为这不可能if (subscribedTopicArray.length<publishTopicArray.length){if (!subscribedTopicArray[subscribedTopicArray.length-1].equals("#")){return false;}}//对两个topic进行比较for (int i = 0; i < publishTopicArray.length && i < subscribedTopicArray.length; i++) {//如果匹配成功或者匹配到了+，进行下一层匹配if (subscribedTopicArray[i].equals(publishTopicArray[i])||subscribedTopicArray[i].equals("+")){continue;}//如果匹配到了#，直接通过if (subscribedTopicArray[i].equals("#")) {break;}return false;}return true;}
isValidTopic方法
用于判断主题是否合法。它会检查主题是否包含空格，并且要么以"/#“结尾，要么不包含”#"。
public boolean isValidTopic(String topic) {//topic 不能包含任何空格，并且要么以 /# 结尾，要么不包含 #return (!topic.matches(".*\\s+.*"))&&(topic.matches(".*(?:\\/#)?$"));}
完整代码
package com.yichen.starter;import io.netty.handler.codec.mqtt.MqttProperties;
import io.netty.handler.codec.mqtt.MqttQoS;
import io.vertx.core.AbstractVerticle;
import io.vertx.core.buffer.Buffer;
import io.vertx.mqtt.MqttEndpoint;
import io.vertx.mqtt.MqttServer;
import io.vertx.mqtt.MqttTopicSubscription;
import io.vertx.mqtt.messages.codes.MqttSubAckReasonCode;import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;/*
* 缺少
* */
public class MqttVertical extends AbstractVerticle {private static Map<String, List<MqttEndpoint>> topicSubscribers;//存储每个topic的订阅关系private static Map<MqttEndpoint, List<String>> subscriptions;//存储每个设备订阅的topic@Overridepublic void start() throws Exception {MqttServer mqttServer = MqttServer.create(vertx);topicSubscribers = new HashMap<>();subscriptions=new HashMap<>();mqttServer.endpointHandler(endpoint -> {//使用lambda表达式实现了endpointHandler方法，传入参数endpoint；System.out.println("MQTT client [" + endpoint.clientIdentifier() + "] request to connect, clean session = " + endpoint.isCleanSession());if (endpoint.auth() != null) {System.out.println("[username = " + endpoint.auth().getUsername() + ", password = " + endpoint.auth().getPassword() + "]");}System.out.println("[properties = " + endpoint.connectProperties() + "]");// accept connection from the remote clientendpoint.accept(false);SubscribeHandle(endpoint);UnSubscribeHandle(endpoint);ReceiveHandle(endpoint);DisConnectHandle(endpoint);});mqttServer.listen(ar -> {if (ar.succeeded()) {System.out.println("MQTT server is listening on port " + ar.result().actualPort());} else {System.out.println("Error on starting the server");ar.cause().printStackTrace();}});}/** 设备断开处理* */private void DisConnectHandle(MqttEndpoint endpoint) {endpoint.disconnectMessageHandler(disconnectMessage -> {System.out.println("Received disconnect from client, reason code = " + disconnectMessage.code());System.out.println("Client "+endpoint.auth().getUsername()+"disconnect with");//对两个映射订阅关系的列表进行更新for (String topic:subscriptions.get(endpoint)){topicSubscribers.get(topic).remove(endpoint);System.out.println("["+topic+"]");}subscriptions.remove(endpoint);});}/**处理订阅消息* */private void SubscribeHandle(MqttEndpoint endpoint) {endpoint.subscribeHandler(subscribe -> {Boolean IsValidTopic=false;//存储订阅消息中要订阅的topic的列表List<MqttTopicSubscription> topicSubscriptions = subscribe.topicSubscriptions();//存储订阅topic Qos级别的列表List<MqttSubAckReasonCode> reasonCodes = new ArrayList<>();//遍历列表for (MqttTopicSubscription s : topicSubscriptions) {//topicString topic = s.topicName();//Qos级别MqttQoS qos = s.qualityOfService();//判断topic是否合法if (!isValidTopic(topic)){//不合法则向设备发送消息endpoint.publish(topic, Buffer.buffer("非法topic，topic不可包含空格"), qos, false, false);continue;}else {IsValidTopic=true;}System.out.println("Subscription for " + topic + " with QoS " + qos);reasonCodes.add(MqttSubAckReasonCode.qosGranted(qos));//判断是否已有此topic，如果有则直接添加，没有则新建键值对if (!topicSubscribers.containsKey(topic)) {topicSubscribers.put(topic, new ArrayList<MqttEndpoint>());}topicSubscribers.get(topic).add(endpoint);//同上if (!subscriptions.containsKey(endpoint)) {subscriptions.put(endpoint, new ArrayList<String>());}subscriptions.get(endpoint).add(topic);}if(IsValidTopic){endpoint.subscribeAcknowledge(subscribe.messageId(), reasonCodes, MqttProperties.NO_PROPERTIES);}});}/** 处理退订* */private void UnSubscribeHandle(MqttEndpoint endpoint) {endpoint.unsubscribeHandler(unsubscribe -> {//遍历要退订的topicfor (String unsubscribedTopic : unsubscribe.topics()) {topicSubscribers.get(unsubscribedTopic).remove(endpoint);//如果某topic的订阅列表为空，删除topicif (topicSubscribers.get(unsubscribedTopic).size() == 0) {topicSubscribers.remove(unsubscribedTopic);}subscriptions.get(endpoint).remove(unsubscribedTopic);//同上if (subscriptions.get(endpoint).size()==0){subscriptions.remove(endpoint);}System.out.println("unsubscribed :" + endpoint.auth().getUsername() + "for" + unsubscribedTopic);}endpoint.unsubscribeAcknowledge(unsubscribe.messageId());});}private void ReceiveHandle(MqttEndpoint endpoint) {endpoint.publishHandler(publish -> {String topic = publish.topicName();Buffer payload = publish.payload();//对topic的合法性进行判断if (!isValidTopic(topic)){endpoint.publish(topic, Buffer.buffer("非法topic，topic不可包含空格"), MqttQoS.AT_MOST_ONCE, false, false);return;}//记录日志接收到设备发布的消息System.out.println("Received message [" + publish.payload().toString(Charset.defaultCharset()) + "] with QoS [" + publish.qosLevel() + "]");if (publish.qosLevel() == MqttQoS.AT_LEAST_ONCE) {endpoint.publishAcknowledge(publish.messageId());} else if (publish.qosLevel() == MqttQoS.EXACTLY_ONCE) {endpoint.publishReceived(publish.messageId());}//遍历订阅关系，进行消息发布for (Map.Entry<String, List<MqttEndpoint>> entry : topicSubscribers.entrySet()) {String subscribedTopic = entry.getKey();//被订阅的topicList<MqttEndpoint> subscribers = entry.getValue();//订阅上方topic的订阅者//判断消息发布的topic是否能和被设备订阅的topic按照规则匹配if (isTopicMatch(subscribedTopic, topic)) {//若匹配，则遍历topic订阅者列表，并进行消息发布for (MqttEndpoint subscriber : subscribers) {subscriber.publish(topic, payload, publish.qosLevel(), publish.isDup(), publish.isRetain());}}}});endpoint.publishAcknowledgeHandler(messageId -> {System.out.println("received ack for message =" + messageId);}).publishReceivedHandler(messageId -> {endpoint.publishRelease(messageId);}).publishCompletionHandler(messageId -> {System.out.println("Received ack for message =" + messageId);});endpoint.publishReleaseHandler(endpoint::publishComplete);}
/*
* 判断topic是否匹配
* */private boolean isTopicMatch(String subscribedTopic, String publishedTopic) {String[] publishTopicArray = publishedTopic.split("/");String[] subscribedTopicArray = subscribedTopic.split("/");//将两个要比较的topic分割//订阅的topic长度不能比发布的topic长一个以上if (subscribedTopicArray.length - 1 > publishTopicArray.length) {return false;}//如果发布的topic长度比订阅的topic长度要长//并且订阅的topic最后不是以#结尾都返回false，因为这不可能if (subscribedTopicArray.length<publishTopicArray.length){if (!subscribedTopicArray[subscribedTopicArray.length-1].equals("#")){return false;}}//对两个topic进行比较for (int i = 0; i < publishTopicArray.length && i < subscribedTopicArray.length; i++) {//如果匹配成功或者匹配到了+，进行下一层匹配if (subscribedTopicArray[i].equals(publishTopicArray[i])||subscribedTopicArray[i].equals("+")){continue;}//如果匹配到了#，直接通过if (subscribedTopicArray[i].equals("#")) {break;}return false;}return true;}public boolean isValidTopic(String topic) {//topic 不能包含任何空格，并且要么以 /# 结尾，要么不包含 #return (!topic.matches(".*\\s+.*"))&&(topic.matches(".*(?:\\/#)?$"));}
}最后
以上就是我的全部代码和相关内容解释，如果有疑问欢迎评论区交流，如果帮到你了可以点个赞
这篇关于Vert.x框架实现MQTT服务，代码实现及其详解的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
