最近项目用到了mqtt，所以记录下SpringBoot集成MQTT的步骤和注意事项，整理一下知识，方便自己和他人。
一、pom文件里引入maven依赖jar包
<dependency> <groupId>org.springframework.integration</groupId> <artifactId>spring-integration-mqtt</artifactId> <version>5.3.2.RELEASE</version> </dependency>
二、在application.yml配置文件里加入mqtt配置信息
snake: server: mqttAddr: 162.11.22.33:1883 mqttUser: admin mqttPwd: 111111
三、新建配置映射类SnakeServerProperties
@Data @Component @ConfigurationProperties(prefix = "snake.server") public class SnakeServerProperties { private String mqttPwd; private String mqttAddr; private String mqttUser; }
四、新建mqtt连接的工厂类MqttFactory
里面会有一个getInstance方法，用来构造MqttClient。
这边需要注意的有两点：
1.这边要考虑mqtt断开自动重连的情况。
2.如果要分布式部署，clientId不能设置成一样的，不然会导致多个实例相同mqttClient抢占连接。这会导致明明获取到mqttClient，但发送消息却报异常。
import com.alibaba.fastjson.JSONObject; import lombok.extern.slf4j.Slf4j; import org.eclipse.paho.client.mqttv3.MqttClient; import org.eclipse.paho.client.mqttv3.MqttConnectOptions; import org.eclipse.paho.client.mqttv3.MqttException; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import java.util.HashMap; import java.util.concurrent.ConcurrentHashMap; /** * @Author: 夏威夷8080 * @Date: 2022/8/12 15:38 */ @Slf4j @Component public class MqttFactory { private ConcurrentHashMap<String, MqttClient> clientMap = new ConcurrentHashMap<>(); @Autowired private SnakeServerProperties snakeServerProperties; /** * 初始化客户端 */ public MqttClient getInstance(String clientId) { MqttClient client = null; String key = clientId; if (clientMap.get(key) == null) { try { client = new MqttClient("tcp://" + snakeServerProperties.getMqttAddr(), clientId); // MQTT配置对象 MqttConnectOptions mqttConnectOptions = new MqttConnectOptions(); // 设置自动重连, 其它具体参数可以查看MqttConnectOptions mqttConnectOptions.setAutomaticReconnect(true); // 设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接 // mqttConnectOptions.setCleanSession(true); // 设置超时时间 单位为秒 mqttConnectOptions.setConnectionTimeout(10); mqttConnectOptions.setUserName(snakeServerProperties.getMqttUser()); mqttConnectOptions.setPassword(snakeServerProperties.getMqttPwd().toCharArray()); // mqttConnectOptions.setServerURIs(new String[]{url}); // 设置会话心跳时间 单位为秒 mqttConnectOptions.setKeepAliveInterval(10); // 设置“遗嘱”消息的话题，若客户端与服务器之间的连接意外中断，服务器将发布客户端的“遗嘱”消息。 // mqttConnectOptions.setWill("willTopic", "offline".getBytes(), 2, false); if (!client.isConnected()) { client.connect(mqttConnectOptions); } log.info("MQTT创建client成功={}", JSONObject.toJSONString(client)); clientMap.put(key, client); } catch (MqttException e) { log.error("MQTT连接消息服务器[{}]失败", key + "-" + snakeServerProperties.getMqttAddr()); } } else { client = clientMap.get(key); log.info("MQTT从map里获取到client={}", JSONObject.toJSONString(client)); if (!client.isConnected()) { // 如果缓存里的client已经断开，则清除该缓存，再重新创建客户端连接 clientMap.remove(key); this.getInstance(clientId); } } return client; } }
五、新建MqttTemplate模板类
里面定义了发送消息和订阅消息两个方法。
import com.alibaba.fastjson.JSONObject; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.google.common.base.Throwables; import lombok.extern.slf4j.Slf4j; import org.eclipse.paho.client.mqttv3.IMqttMessageListener; import org.eclipse.paho.client.mqttv3.MqttClient; import org.eclipse.paho.client.mqttv3.MqttException; import org.eclipse.paho.client.mqttv3.MqttMessage; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import java.nio.charset.StandardCharsets; /** * @Author: 夏威夷8080 * @Date: 2022/8/12 15:47 */ @Slf4j @Component public class MqttTemplate { @Autowired private MqttFactory mqttFactory; /** * 发送消息 * * @param topic 主题 * @param data 消息内容 */ public void send(String clientId, String topic, Object data) { // 获取客户端实例 MqttClient client = mqttFactory.getInstance(clientId); try { // 转换消息为json字符串 String json = JSONObject.toJSONString(data); log.info("MQTT主题[{}]发送消息...\r\n{}", topic, json); client.publish(topic, new MqttMessage(json.getBytes(StandardCharsets.UTF_8))); } catch (MqttException e) { log.error("MQTT主题[{}]发送消息失败,{}", topic, Throwables.getStackTraceAsString(e)); } } /** * 订阅主题 * * @param topic 主题 * @param listener 消息监听处理器 */ public void subscribe(String clientId, String topic, IMqttMessageListener listener) { MqttClient client = mqttFactory.getInstance(clientId); try { log.info("MQTT订阅主题[{}]...", topic); client.subscribe(topic, listener); } catch (MqttException e) { log.error("MQTT订阅主题[{}]失败,{}", topic, Throwables.getStackTraceAsString(e)); } } }
六、新建业务操作MQTT处理类MyHandler
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import javax.annotation.PostConstruct; /** * @Author: 夏威夷8080 * @Date: 2022/8/12 15:59 */ @Component public class MyHandler { @Autowired private MqttTemplate mqttTemplate; public void listener(String clientId, String topic) { mqttTemplate.subscribe(clientId, topic, new SnakeMqttMessageListener()); } public void send(String clientId, String topic, CmdRequest cmdRequest) { mqttTemplate.send(clientId, topic, cmdRequest); } }
七、新建自己的mqtt消息监听处理类，需要实现IMqttMessageListener接口
这边无法直接注入bean，需要从applicationContext里拿
import cn.hutool.json.JSONUtil; import com.alibaba.fastjson.JSON; import lombok.extern.slf4j.Slf4j; import org.eclipse.paho.client.mqttv3.IMqttMessageListener; import org.eclipse.paho.client.mqttv3.MqttMessage; import org.springframework.context.ApplicationContext; import org.springframework.stereotype.Component; /** * @Author: 夏威夷8080 * @Date: 2022/8/12 15:50 */ @Slf4j public class SnakeMqttMessageListener implements IMqttMessageListener { /** * 处理消息 * * @param topic 主题 * @param mqttMessage 消息 */ @Override public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception { log.info("MQTT实时订阅主题[{}]发来消息[{}]", topic, new String(mqttMessage.getPayload())); ApplicationContext applicationContext = SpringContextHolder.getApplicationContext(); xxxxxxx xxx = applicationContext.getBean(xxxx.class); } }
八、顺便把工具类也贴出来SpringContextHolder
import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.DisposableBean; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.context.ApplicationEvent; import org.springframework.context.annotation.Lazy; import org.springframework.stereotype.Service; /** * @author 夏威夷8080 * @date 2018/6/27 Spring 工具类 */ @Slf4j @Service @Lazy(false) public class SpringContextHolder implements ApplicationContextAware, DisposableBean { private static ApplicationContext applicationContext = null; /** * 取得存储在静态变量中的ApplicationContext. */ public static ApplicationContext getApplicationContext() { return applicationContext; } /** * 实现ApplicationContextAware接口, 注入Context到静态变量中. */ @Override public void setApplicationContext(ApplicationContext applicationContext) { SpringContextHolder.applicationContext = applicationContext; } /** * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型. */ @SuppressWarnings("unchecked") public static <T> T getBean(String name) { return (T) applicationContext.getBean(name); } /** * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型. */ public static <T> T getBean(Class<T> requiredType) { return applicationContext.getBean(requiredType); } /** * 清除SpringContextHolder中的ApplicationContext为Null. */ public static void clearHolder() { if (log.isDebugEnabled()) { log.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext); } applicationContext = null; } /** * 发布事件 * @param event */ public static void publishEvent(ApplicationEvent event) { if (applicationContext == null) { return; } applicationContext.publishEvent(event); } /** * 实现DisposableBean接口, 在Context关闭时清理静态变量. */ @Override public void destroy() { SpringContextHolder.clearHolder(); } }
OK，SpringBoot集成MQTT的步骤和注意事项到这边就介绍完了，希望对大家有帮助，有问题可以在下面留言。