其中 pom.xml 文件的依赖配置、基础连接配置、 application.properties 文件的 MQTT 服务器配置同前文一样。

一、实现 MQTT 消息的订阅

动态监听topic没有实现！

package com.gyz.mqtt.config;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.integration.channel.DirectChannel;
import org.springframework.integration.core.MessageProducer;
import org.springframework.integration.mqtt.core.MqttPahoClientFactory;
import org.springframework.integration.mqtt.inbound.MqttPahoMessageDrivenChannelAdapter;
import org.springframework.integration.mqtt.support.DefaultPahoMessageConverter;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHandler;
import org.springframework.messaging.MessagingException;
/**
 * MQTT配置，消费者
 *
 * @author gong_yuzhuo
 */
@Configuration
public class MqttReceiverConfig {
    /**
     * 订阅的bean名称
     */
    public static final String CHANNEL_NAME_IN = "mqttInboundChannel";
    public MqttPahoMessageDrivenChannelAdapter adapter;
    /** 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 */
    private static final byte[] WILL_DATA;
    static {
        WILL_DATA = "offline".getBytes();
    }
    @Value("${mqtt.username}")
    private String username;
    @Value("${mqtt.password}")
    private String password;
    @Value("${mqtt.host}")
    private String url;
    @Value("${mqtt.receiver.clientId}")
    private String clientId;
    @Value("${mqtt.receiver.defaultTopic}")
    private String defaultTopic;
    /**
     * MQTT信息通道（消费者）
     */
    @Bean(name = CHANNEL_NAME_IN)
    public MessageChannel mqttInboundChannel() {
        return new DirectChannel();
    }
    /**
     * MQTT消息订阅绑定（消费者）
     */
    @Bean
    public MessageProducer inbound(MqttPahoClientFactory factory) {
        // 可以同时消费（订阅）多个Topic
        adapter = new MqttPahoMessageDrivenChannelAdapter(
                clientId, factory,
                StringUtils.split(defaultTopic, ","));
        adapter.setCompletionTimeout(5000);
        adapter.setConverter(new DefaultPahoMessageConverter());
        adapter.setQos(1);
        // 设置订阅通道
        adapter.setOutputChannel(mqttInboundChannel());
        return adapter;
    }
    /**
     * MQTT消息处理器（消费者）
     */
    @Bean
    @ServiceActivator(inputChannel = CHANNEL_NAME_IN)
    public MessageHandler handler() {
        return new MessageHandler() {
            @Override
            public void handleMessage(Message<?> message) throws MessagingException {
                String topic = message.getHeaders().get("mqtt_receivedTopic").toString();
                String msg = message.getPayload().toString();
                System.out.println("\n--------------------START-------------------\n" +
                        "接收到订阅消息:\ntopic:" + topic + "\nmessage:" + msg +
                        "\n---------------------END--------------------");
            }
        };
    }
}

二、测试运行

项目启动后，我们使用 MQTTBox 对“hangge”这个主题，发送一条消息：

可以看到 SprinBoot 项目这边成功接收到消息并打印出来：

发送“hello”主题的消息：

可以看到“hello”主题消息也已被接收成功

注意主题配置