springboot mqtt服务

Spring Boot提供了对MQTT（Message Queuing Telemetry Transport）协议的支持，可以轻松地在Spring Boot应用程序中集成MQTT服务。使用Spring Boot的MqttPahoClient库可以很方便地实现与MQTT代理的通信。

要在Spring Boot应用程序中使用MQTT服务，需要添加以下依赖项到你的pom.xml文件中：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-integration</artifactId>
</dependency>
<dependency>
    <groupId>org.eclipse.paho</groupId>
    <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
    <version>1.2.5</version>
</dependency>

然后，你可以使用`@EnableIntegration`注解启用Spring Integration，并使用`@Bean`注解创建一个基于MqttPahoClient的消息监听器容器（MessageListenerContainer）。示例如下：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.integration.annotation.IntegrationComponentScan;
import org.springframework.integration.annotation.MessagingGateway;
import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.integration.channel.DirectChannel;
import org.springframework.integration.config.EnableIntegration;
import org.springframework.integration.core.MessageProducer;
import org.springframework.integration.core.MessagingTemplate;
import org.springframework.integration.dsl.IntegrationFlow;
import org.springframework.integration.dsl.IntegrationFlows;
import org.springframework.integration.dsl.Pollers;
import org.springframework.integration.mqtt.core.DefaultMqttPahoClientFactory;
import org.springframework.integration.mqtt.inbound.MqttPahoMessageDrivenChannelAdapter;
import org.springframework.integration.mqtt.outbound.MqttPahoMessageHandler;

@Configuration
@EnableIntegration
@IntegrationComponentScan
public class MqttConfig {

    private static final String MQTT_BROKER = "tcp://localhost:1883";
    private static final String CLIENT_ID = "mqttClientId";
    private static final String TOPIC = "your/topic";

    @Bean
    public DefaultMqttPahoClientFactory mqttClientFactory() {
        DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
        factory.setServerURIs(MQTT_BROKER);
        return factory;
    }

    @Bean
    public MessageProducer inbound() {
        MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter(CLIENT_ID,
                mqttClientFactory(), TOPIC);
        adapter.setCompletionTimeout(5000);
        adapter.setConverter(new DefaultPahoMessageConverter());
        adapter.setQos(1);
        return adapter;
    }

    @Bean
    public MessageProducer outbound() {
        MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler(CLIENT_ID, mqttClientFactory());
        messageHandler.setAsync(true);
        messageHandler.setDefaultTopic(TOPIC);
        return messageHandler;
    }

    @Bean
    public IntegrationFlow mqttInFlow() {
        return IntegrationFlows.from(inbound())
                .transform(p -> p + ", received from MQTT")
                .handle(logger())
                .get();
    }

    @Bean
    @ServiceActivator(inputChannel = "mqttOutboundChannel")
    public MessageHandler mqttOutbound() {
        MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler(CLIENT_ID, mqttClientFactory());
        messageHandler.setAsync(true);
        messageHandler.setDefaultTopic(TOPIC);
        return messageHandler;
    }

    @Bean
    public ApplicationRunner runner(MqttGateway gateway) {
        return args -> {
            gateway.sendToMqtt("Test message");
        };
    }

    @Bean
    public MessageChannel mqttOutboundChannel() {
        return new DirectChannel();
    }

    @MessagingGateway(defaultRequestChannel = "mqttOutboundChannel")
    public interface MqttGateway {
        void sendToMqtt(String data);
    }

    @Bean
    public LoggingHandler logger() {
        return new LoggingHandler("INFO");
    }
}

上述示例展示了如何配置一个支持MQTT的Spring Boot应用程序。在示例中，我们创建了一个基于MqttPahoClient的消息监听器容器，并通过`@EnableIntegration`和`@IntegrationComponentScan`启用和扫描Spring Integration配置。