Spring boot + MQTT（emq）

原文地址：https://blog.csdn.net/qq_41018959/article/details/81076055
https://blog.csdn.net/hao114500043/article/details/81742849

1，pom配置，引入相关jar:

<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-stream</artifactId>
</dependency>
<dependency>
   <groupId>org.springframework.integration</groupId>
   <artifactId>spring-integration-mqtt</artifactId>
</dependency> 

2，配置MQTT服务器基本信息，在springBoot配置文件application.properties中配置，添加如下：

#MQTT配置信息
#MQTT-服务器连接地址，如果有多个，用逗号隔开，如：tcp://127.0.0.1:61613，tcp://192.168.2.133:61613
qjzh.mqtt.host=tcp://192.168.49.10:1883
#MQTT-连接服务器默认客户端ID
qjzh.mqtt.clientid=mqttjs_e8022a4d0b111
#MQTT-用户名
qjzh.mqtt.username=aaaa
#MQTT-密码
qjzh.mqtt.password=1111
#MQTT-默认的消息推送主题，实际可在调用接口时指定
qjzh.mqtt.topic=7g_m2m/device/update
#连接超时
qjzh.mqtt.timeout=1000

3，创建MQTT相关配置类：

@Component
public class MqttPushClient {
    private static final Logger LOGGER = LoggerFactory.getLogger(MqttPushClient.class);
    
    @Autowired
	private PushCallback pushCallback;
    
    private static MqttClient client;
 
    public static MqttClient getClient() {
        return client;
    }
 
    public static void setClient(MqttClient client) {
        MqttPushClient.client = client;
    }
 
    public void connect(String host, String clientID, String username, String password, int timeout, int keepalive){
        MqttClient client;
        try {
            client = new MqttClient(host, clientID, new MemoryPersistence());
            MqttConnectOptions options = new MqttConnectOptions();
            options.setCleanSession(true);
            options.setUserName(username);
            options.setPassword(password.toCharArray());
            options.setConnectionTimeout(timeout);
            options.setKeepAliveInterval(keepalive);
            MqttPushClient.setClient(client);
            try {
                client.setCallback(pushCallback);
                client.connect(options);
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    /**
     * 发布，默认qos为0，非持久化
     * @param topic
     * @param pushMessage
     */
    public void publish(String topic,String pushMessage){
        publish(0, false, topic, pushMessage);
    }
 
    /**
     * 发布
     * @param qos
     * @param retained
     * @param topic
     * @param pushMessage
     */
    public void publish(int qos,boolean retained,String topic,String pushMessage){
        MqttMessage message = new MqttMessage();
        message.setQos(qos);
        message.setRetained(retained);
        message.setPayload(pushMessage.getBytes());
        MqttTopic mTopic = MqttPushClient.getClient().getTopic(topic);
        if(null == mTopic){
            LOGGER.error("topic not exist");
        }
        MqttDeliveryToken token;
        try {
            token = mTopic.publish(message);
            token.waitForCompletion();
        } catch (MqttPersistenceException e) {
            e.printStackTrace();
        } catch (MqttException e) {
            e.printStackTrace();
        }
    }
 
    /**
     * 订阅某个主题，qos默认为0
     * @param topic
     */
    public void subscribe(String topic){
        subscribe(topic,0);
    }
 
    /**
     * 订阅某个主题
     * @param topic
     * @param qos
     */
    public void subscribe(String topic,int qos){
        try {
            MqttPushClient.getClient().subscribe(topic, qos);
        } catch (MqttException e) {
            e.printStackTrace();
        }
    }
}

4、Spring boot 读取自定义properties配置文件，同时初始化配置类

@Component
@Configuration
@ConfigurationProperties(MqttConfiguration.PREFIX)
public class MqttConfiguration {
	
	@Autowired
	private MqttPushClient mqttPushClient;
	
	public static final String PREFIX = "qjzh.mqtt";
    private String host;
    private String clientid;
    private String username;
    private String password;
    private String topic;
    private int timeout;
    private int keepalive;
 
    public String getClientid() {
        return clientid;
    }
 
    public void setClientid(String clientid) {
        this.clientid = clientid;
    }
 
    public String getUsername() {
        return username;
    }
 
    public void setUsername(String username) {
        this.username = username;
    }
 
    public String getPassword() {
        return password;
    }
 
    public void setPassword(String password) {
        this.password = password;
    }
 
    public String getTopic() {
        return topic;
    }
 
    public void setTopic(String topic) {
        this.topic = topic;
    }
 
    public int getTimeout() {
        return timeout;
    }
 
    public void setTimeout(int timeout) {
        this.timeout = timeout;
    }
 
    public int getKeepalive() {
        return keepalive;
    }
 
    public void setKeepalive(int keepalive) {
        this.keepalive = keepalive;
    }
 
    public String getHost() {
        return host;
    }
 
    public void setHost(String host) {
        this.host = host;
    }
    
    @Bean
    public MqttPushClient getMqttPushClient(){
        mqttPushClient.connect(host, clientid, username, password, timeout,keepalive);
        return mqttPushClient;
    }
}

5、消费监听类，在messageArrived方法中会收到mqtt中的数据，需要处理的话就在当前方法中操作

public class PushCallback implements MqttCallback {
 
    @Override
    public void connectionLost(Throwable cause) {
        // 连接丢失后，一般在这里面进行重连
        System.out.println("连接断开，可以做重连");
    }
 
    @Override
    public void deliveryComplete(IMqttDeliveryToken token) {
        System.out.println("deliveryComplete---------" + token.isComplete());
    }
 
    @Override
    public void messageArrived(String topic, MqttMessage message) throws Exception {
        // subscribe后得到的消息会执行到这里面
        System.out.println("接收消息主题 : " + topic);
        System.out.println("接收消息Qos : " + message.getQos());
        System.out.println("接收消息内容 : " + new String(message.getPayload()));
    }
}