初学者springboot集成mqtt实例

最近开发一款物联网相关设备，接触到了mqtt协议，网上找了很多资料，但基本都是“犹抱琵琶半遮面”，总有些内容缺失。可能是作者们认为那些太基础的内容不需要说，但对于我这种初学者来说，就很不善了。
所幸，历经坎坷，总算调通了一个，记录在这里，给像我一样的小白提供一些参考。
首先，基于mqqt协议的通信，你得有一个服务器，这个我都不知道。。。。。。（坑1）
mqtt服务的基本原理是，大家同服务器连接后，可以向服务器订阅n个“主题”，比如“hello”“test”等。然后有张三需要向服务器发送消息时，会告知服务器自己所发送的消息是什么主题的，比如“hello"。服务器收到张三的主题为“hello”的消息后，会查看都有谁向自己订阅了“hello”主题的消息，然后就把消息转发到那些订阅者那里去，完成通信。
我用的是emqx作为mqtt服务器软件，当然还有其他的开源的，这个好找，不多说了。
emqx我放在了阿里云上新购买的实例上。新买实例后，需要修改密码并重启后才能连接到实例上，这一点他们没有提示（坑2）。
然后，安装好，运行起来emqx，发现远程端口没打开，又学习了安全方面的设置，还有监听0.0.0.0地址的端口才是公网端口（坑3）。
把服务器软件装好后，用通讯猫或者paho测试了一下，能够远程正常连接并发送主题（一定要先测试好）。
最后是springboot整合mqtt做客户端部分。

先上原码：放心下载，不需要C币

1. pox.xml 引入需要的包，主要是最后面3个依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.2.5.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.bam</groupId>
	<artifactId>mqtt</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
	<name>MQTT-1</name>
	<description>Demo project for Shiro</description>
	<properties>
		<java.version>1.8</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-tomcat</artifactId>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-freemarker</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework.integration</groupId>
			<artifactId>spring-integration-stream</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.integration</groupId>
			<artifactId>spring-integration-mqtt</artifactId>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<optional>true</optional>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>

2. 然后是application.yml

mqtt:
  username: admin							
  password: public						
  host-url: tcp://123.123.123.123:1883		# 你自己服务器的地址和端口，这个需要改 
  clientID: test							# 这个改不改随意，但不同的客户端肯定不能一样
  default-topic: test						# 默认主题
  timeout: 100							   
  keepalive: 100

3. 读取配置文件

package com.bam;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

import lombok.Getter;
import lombok.Setter;

/**
 * @Classname MqttConfig
 * @Description mqtt相关配置信息
 * @Date 2020/3/5 11:00
 * @Created by bam
 */
@Component
@ConfigurationProperties("mqtt")
@Setter
@Getter
public class MqttConfig {
    @Autowired
    private MqttPushClient mqttPushClient;

    /**
     * 用户名
     */
   // @Value("username")
    private String username;
    /**
     * 密码
     */
    private String password;
    /**
     * 连接地址
     */
    private String hostUrl;
    /**
     * 客户Id
     */
    private String clientID;
    /**
     * 默认连接话题
     */
    private String defaultTopic;
    /**
     * 超时时间
     */
    private int timeout;
    /**
     * 保持连接数
     */
    private int keepalive;

    @Bean
    public MqttPushClient getMqttPushClient() {
    	System.out.println("hostUrl: "+ hostUrl);
    	System.out.println("clientID: "+ clientID);
    	System.out.println("username: "+ username);
    	System.out.println("password: "+ password);
    	System.out.println("timeout: "+timeout);
    	System.out.println("keepalive: "+ keepalive);
        mqttPushClient.connect(hostUrl, clientID, username, password, timeout, keepalive);
        // 以/#结尾表示订阅所有以test开头的主题
        mqttPushClient.subscribe(defaultTopic, 0);
        return mqttPushClient;
    }
}

4. MqttPushClient 发布消息类

package com.bam;

import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;

/**
 * 
 * @author bam
 * 2020年3月5日
 * MqttPushClient.java
 *
 */
@Component
public class MqttPushClient {
    private static final Logger logger = LoggerFactory.getLogger(MqttPushClient.class);

    @Autowired
    private PushCallback pushCallback;

    private static MqttClient client;

    private static MqttClient getClient() {
        return client;
    }

    private static void setClient(MqttClient client) {
        MqttPushClient.client = client;
    }

    /**
     * 客户端连接
     *
     * @param host      ip+端口
     * @param clientID  客户端Id
     * @param username  用户名
     * @param password  密码
     * @param timeout   超时时间
     * @param keepalive 保留数
     */
    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
     *
     * @param qos         连接方式
     * @param retained    是否保留
     * @param topic       主题
     * @param pushMessage 消息体
     */
    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
     *
     * @param topic 主题
     * @param qos   连接方式
     */
    public void subscribe(String topic, int qos) {
        logger.info("开始订阅主题" + topic);
        try {
            MqttPushClient.getClient().subscribe(topic, qos);
        } catch (MqttException e) {
            e.printStackTrace();
        }
    }
}

5. 收到消息的处理

package com.bam;

import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * @Classname PushCallback
 * @Description 消费监听类
 * @Date 2019/4/11 23:31
 * @Created by Jack
 */
@Component
public class PushCallback implements MqttCallback {
    private static final Logger logger = LoggerFactory.getLogger(MqttPushClient.class);

    @Autowired
    private MqttConfig mqttConfig;

    private static MqttClient client;

    @Override
    public void connectionLost(Throwable throwable) {
        // 连接丢失后，一般在这里面进行重连
        logger.info("连接断开，可以做重连");
        if (null != client) {
            mqttConfig.getMqttPushClient();
        }
    }

    @Override
    public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
        // subscribe后得到的消息会执行到这里面
        logger.info("接收消息主题 : " + topic);
        logger.info("接收消息Qos : " + mqttMessage.getQos());
        logger.info("接收消息内容 : " + new String(mqttMessage.getPayload()));
    }

    @Override
    public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
        logger.info("deliveryComplete---------" + iMqttDeliveryToken.isComplete());
    }
}

6. 发送方法测试

package com.bam;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;

/**
 * 
 * @author bam
 * 2020年3月5日
 * TestController.java
 *
 */
@RestController
@RequestMapping("/")
public class TestController {
 
    @Autowired
    private MqttPushClient mqttPushClient;

    @GetMapping(value = "/publishTopic")
    public String publishTopic() {
    	String topicString = "test";
        mqttPushClient.publish(0, false, topicString, "测试一下发布消息");
        return "ok";
    }
 // 发送自定义消息内容（使用默认主题）
    @RequestMapping("/publishTopic/{data}")
    public void test1(@PathVariable("data") String data) {
    	String topicString = "test";
    	mqttPushClient.publish(0,false,topicString, data);
    	return "ok";
    }
 
    // 发送自定义消息内容，且指定主题
    @RequestMapping("/publishTopic/{topic}/{data}")
    public void test2(@PathVariable("topic") String topic, @PathVariable("data") String data) {
    	mqttPushClient.publish(0,false,topic, data);
    	return "ok";
    }
}

7. 上图

paho收消息截图

eclipse后台截图