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Most people do not understand the knowledge points of this "Spring boot how to integrate MQTT" article, so the editor summarizes the following content, detailed content, clear steps, and has a certain reference value. I hope you can get something after reading this article. Let's take a look at this "Spring boot how to integrate MQTT" article.

I. brief introduction

MQTT (Message Queuing Telemetry Transport, message queuing Telemetry Transport Protocol) is a "lightweight" communication protocol based on publish / subscribe (publish/subscribe) mode, which can provide real-time and reliable message service for connecting remote devices with very little code and limited bandwidth. At present, it is widely used in the Internet of things, small devices, mobile applications and so on.

II. Main characteristics

(1) using the publish / subscribe message pattern to provide one-to-many message publishing and uncoupling the application.

(2) message transmission that masks payload content.

(3) use TCP/IP to provide network connection.

(4) there are three kinds of quality of service for message publishing:

"at most once," the release of messages depends entirely on the underlying TCP/IP network. Messages can be lost or duplicated. This level can be used in the case of environmental sensor data, it doesn't matter if you lose a read record, because there will be a second transmission soon. This method is mainly ordinary APP push, if your smart device is not online when the message is pushed, and the push is not received in the past, it will not be received when you connect to the Internet again.

"at least once" to ensure that the message arrives, but message repetition may occur.

"only once", make sure the message arrives once. This level can be used in some more stringent billing systems. In the billing system, duplicate or lost messages can lead to incorrect results. This highest quality messaging service can also be used for instant messaging APP push, ensuring that users receive it and only receive it once.

(5) small transmission, the overhead is very small (the fixed-length header is 2 bytes), and protocol switching is minimized to reduce network traffic.

(6) the mechanism for notifying the parties concerned of abnormal client interruptions using Last Will and Testament features.

Last Will: the last note mechanism, which is used to notify other devices under the same topic that the device that sent the last message has been disconnected.

Testament: a testamentary mechanism that functions like Last Will.

Third, integration step 1. Introduce the related jar package org.springframework.integration spring-integration-stream org.springframework.integration spring-integration-mqtt2. The core configuration class @ Configurationpublic class MqttConfig {@ Autowired private MqttProperties mqttProperties; / * Connector * @ return * / @ Bean public MqttConnectOptions getMqttConnectOptions () {MqttConnectOptions mqttConnectOptions = new MqttConnectOptions (); / / sets whether to empty session,false means that the server keeps the connection record of the client, and true means that every time you connect to the server, you connect to mqttConnectOptions.setCleanSession (true) with a new identity. / / set the timeout. Default is 30 seconds mqttConnectOptions.setConnectionTimeout (mqttProperties.getConnectionTimeOut ()); mqttConnectOptions.setKeepAliveInterval (mqttProperties.getKeepAlive ()); mqttConnectOptions.setAutomaticReconnect (true); / / set the connection user name mqttConnectOptions.setUserName (mqttProperties.getUsername ()); / / set the connection password mqttConnectOptions.setPassword (mqttProperties.getPassword (). ToCharArray ()) / / Server address mqttConnectOptions.setServerURIs (new String [] {mqttProperties.getUrl ()}); mqttConnectOptions.setKeepAliveInterval (2); return mqttConnectOptions;} / * MQTT client * @ return * / @ Bean ("mqttClientFactory") public MqttPahoClientFactory mqttClientFactory () {DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory (); factory.setConnectionOptions (getMqttConnectOptions ()); return factory } / *-configuration of message producer-* / / * MQTT production side release processor * * @ return {@ link org.springframework.messaging.MessageHandler} * / @ Bean @ ServiceActivator (inputChannel = "mqttOutboundChannel") public MessageHandler mqttOutbound () {MqttPahoMessageHandler messageHandler = new MqttPahoMessageHandler (mqttProperties.getProducerClientId () MqttClientFactory () MessageHandler.setAsync (true); return messageHandler;} / * MQTT production release channel * @ return * / @ Bean ("mqttOutboundChannel") public MessageChannel mqttOutboundChannel () {return new DirectChannel () } / *-configuration of message consumers-* / / * * MQTT consumer subscription channel * * @ return {@ link org.springframework.messaging.MessageChannel} * / @ Bean (name = "mqttInboundChannel") Public MessageChannel mqttInboundChannel () {return new DirectChannel () MQTT consumer connection configuration * * @ param channel {@ link org.springframework.messaging.MessageChannel} * @ param factory {@ link org.springframework.integration.mqtt.core.MqttPahoClientFactory} * @ return {@ link org.springframework.integration.core.MessageProducer} * / @ Bean public MessageProducer inbound (@ Qualifier ("mqttInboundChannel") MessageChannel channel @ Qualifier ("mqttClientFactory") MqttPahoClientFactory factory) {MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter (mqttProperties.getConsumerClientId (), factory, "test") Adapter.setCompletionTimeout (30000); adapter.setConverter (new DefaultPahoMessageConverter ()); / / 0 at most, data may be lost / / 1 at least once, data may be repeated / / 2 only once, and the most performance-consuming adapter.setQos (1); / / set subscription channel adapter.setOutputChannel (channel); return adapter } @ ConfigurationProperties ("mqtt") @ Componentpublic class MqttProperties implements Serializable {private static final long serialVersionUID =-1425980007744001158L; private String url; private String username; private String password; private int keepAlive; private int connectionTimeOut; private String producerClientId; private String producerQos; private String consumerClientId; private String consumerQos; private String consumerTopic; private int completionTimeout; private String defaultTopic; / / get, set method omitted} 3. Gateway configuration @ MessagingGateway (defaultRequestChannel = "mqttOutboundChannel") public interface MqttGateway {void sendToMqtt (byte [] data,@Header (MqttHeaders.TOPIC) String topic);} 4. Write a test class @ Autowired private MqttGateway mqttGateway; @ RequestMapping ("/ sendTest") public String sendMqttTest (String msg) {mqttGateway.send ("test", msg); return "OK" } 5.yml configuration information mqtt: url: tcp://localhost:1883 username: test password: test1234 keep-alive: 30 connection-timeout: 3000 producerClientId: test-producer producerQos: 1 consumerClientId: test-consumer consumerQos: 1 deafultTopic: test above is about "how Spring boot integrates MQTT". I believe you all have some understanding. I hope the content shared by the editor will be helpful to you, if you want to know more about it. Please follow the industry information channel.

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