写一个基于springboot的，mqtt和websocket配合使用的例子

### 回答1：

答：基于Spring Boot的MQTT和WebSocket配合使用的例子如下：
1. 创建Spring Boot应用程序，并使用@EnableWebSocketMessageBroker注解将其作为WebSocket服务器配置；
2. 在Spring Boot应用程序中配置MQTT客户端，以实现MQTT和WebSocket协议之间的通信；
3. 在应用程序中创建WebSocket消息处理器，以处理来自客户端的WebSocket消息；
4. 在应用程序中创建MQTT消息处理器，以处理来自客户端的MQTT消息；
5. 使用WebSocket和MQTT客户端发送和接收消息，并使用消息处理器来处理来自客户端的消息。

### 回答2：
以下是一个基于Spring Boot的MQTT和WebSocket配合使用的例子：

首先，在pom.xml文件中添加以下依赖：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-websocket</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.integration</groupId>
        <artifactId>spring-integration-mqtt</artifactId>
    </dependency>
</dependencies>

接下来，创建一个WebSocket配置类（WebSocketConfig.java）：

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/websocket-example").withSockJS();
    }
}

然后，创建一个MQTT配置类（MqttConfig.java）：

@Configuration
@Slf4j
public class MqttConfig {

    @Value("${mqtt.broker.url}")
    private String mqttBrokerUrl;

    @Value("${mqtt.client.id}")
    private String mqttClientId;

    @Bean
    public MqttPahoClientFactory mqttClientFactory() {
        DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
        MqttConnectOptions options = new MqttConnectOptions();
        options.setServerURIs(new String[]{mqttBrokerUrl});
        options.setKeepAliveInterval(60);
        factory.setConnectionOptions(options);
        return factory;
    }

    @Bean
    public AbstractMqttPahoClientFactorySender mqttSender(MqttPahoClientFactory mqttClientFactory) {
        AbstractMqttPahoClientFactorySender sender = new AbstractMqttPahoClientFactorySender(mqttClientFactory, mqttClientId);
        sender.setAsync(true);
        sender.setDefaultQos(1);
        return sender;
    }

    @Bean
    public MessageProducer mqttInbound(MqttPahoClientFactory mqttClientFactory) {
        String clientId = "mqtt-inbound-" + UUID.randomUUID().toString();

        MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter(clientId, mqttClientFactory, "topic1", "topic2");
        adapter.setCompletionTimeout(5000);
        adapter.setConverter(new DefaultPahoMessageConverter());
        adapter.setQos(1);

        return adapter;
    }

    @ServiceActivator(inputChannel = "mqttInboundChannel")
    public void handleMqttMessage(Message<org.eclipse.paho.client.mqttv3.MqttMessage> message) {
        log.info("MQTT Message: " + message.getPayload().toString());
    }
}

最后，创建一个WebSocket控制器类（WebSocketController.java）：

@Controller
@Slf4j
public class WebSocketController {

    @Autowired
    private SimpMessagingTemplate messagingTemplate;

    @MessageMapping("/send-message")
    public void sendMessage(String message) {
        messagingTemplate.convertAndSend("/topic/receive-message", message);
    }

    @SubscribeMapping("/topic/receive-message")
    public void handleSubscribe() {
        log.info("Client subscribed to /topic/receive-message.");
    }
}

以上例子实现了一个简单的功能：通过MQTT发布消息，然后通过WebSocket订阅并接收这些消息，并将其发送到前端页面。你可以根据自己的需求进一步修改和扩展此例子。注意，在应用的配置文件中要提供MQTT的连接URL和客户端ID。

希望这个例子对你有所帮助！

### 回答3：
下面是一个基于Spring Boot的示例，展示了如何使用MQTT和WebSocket进行通信的例子：

首先，我们需要添加以下依赖项到pom.xml文件中：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-mqtt</artifactId>
</dependency>

然后，创建一个WebSocket配置类，用于配置WebSocket的相关设置：

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/ws").withSockJS();
    }
}

接下来，创建一个MqttConfig类，用于配置MQTT的相关设置：

@Configuration
@EnableMqtt
public class MqttConfig {

    @Value("${mqtt.broker}")
    private String broker;

    @Value("${mqtt.username}")
    private String username;

    @Value("${mqtt.password}")
    private String password;

    @Bean
    public MqttPahoClientFactory mqttClientFactory() {
        DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
        MqttConnectOptions options = new MqttConnectOptions();
        options.setServerURIs(new String[]{broker});
        options.setUserName(username);
        options.setPassword(password.toCharArray());
        factory.setConnectionOptions(options);
        return factory;
    }

    @Bean
    public MqttPahoMessageHandler mqttMessageHandler() {
        MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler("mqttClient", mqttClientFactory());
        messageHandler.setAsync(true);
        messageHandler.setDefaultTopic("topic");
        return messageHandler;
    }

    @Bean
    public MessageProducerSupport mqttInbound() {
        MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter("mqttClient", mqttClientFactory(),
                "topic1", "topic2");
        adapter.setCompletionTimeout(5000);
        adapter.setConverter(new DefaultPahoMessageConverter());
        adapter.setQos(1);
        adapter.setOutputChannel(mqttInputChannel());
        return adapter;
    }

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

最后，创建一个WebSocketController类，用于处理WebSocket请求：

@Controller
public class WebSocketController {

    @MessageMapping("/send")
    @SendTo("/topic/messages")
    public String sendMessage(String message) {
        return "Received: " + message;
    }
}

这样，我们就完成了一个基于Spring Boot的MQTT和WebSocket配合使用的例子。通过WebSocket发送消息到`/app/send`，然后通过MQTT接收到的消息将会发送到`/topic/messages`频道，并在WebSocket上进行广播。

请确保在application.properties或application.yml文件中配置了正确的MQTT代理地址、用户名和密码，例如：

mqtt.broker=tcp://localhost:1883
mqtt.username=username
mqtt.password=password

希望这个例子能够帮助到你！