add simple code for MQTT connection

build.gradle

@@ -34,6 +34,7 @@ dependencies {
 	implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.12.0'
 	implementation group: 'org.apache.commons', name: 'commons-text', version: '1.9'
 	implementation group: 'org.apache.tika', name: 'tika-core', version: '2.4.1'
+  implementation group: 'org.springframework.integration', name: 'spring-integration-mqtt', version: '6.0.2'
 	implementation 'net.sf.jasperreports:jasperreports:6.19.1'
 
 	implementation group: 'org.springdoc', name: 'springdoc-openapi-ui', version: '1.6.9'

src/main/java/com/ffii/towngas/config/MqttConsumerCallBack.java

@@ -0,0 +1,25 @@
+package com.ffii.towngas.config;
+
+import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
+import org.eclipse.paho.client.mqttv3.MqttCallback;
+import org.eclipse.paho.client.mqttv3.MqttMessage;
+
+public class MqttConsumerCallBack implements MqttCallback {
+  @Override
+  public void connectionLost(Throwable throwable) {
+    System.out.println("Disconnected with server");
+  }
+
+  @Override
+  public void messageArrived(String topic, MqttMessage message) throws Exception {
+    System.out.println(String.format("Topic: %s", topic));
+    System.out.println(String.format("Qos : %d", message.getQos()));
+    System.out.println(String.format("Content: %s", new String(message.getPayload())));
+    System.out.println(String.format("Retained : %b", message.isRetained()));
+  }
+
+  @Override
+  public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
+
+  }
+}

src/main/java/com/ffii/towngas/config/MqttConsumerConfig.java

@@ -0,0 +1,77 @@
+package com.ffii.towngas.config;
+
+import javax.annotation.PostConstruct;
+
+import org.eclipse.paho.client.mqttv3.MqttClient;
+import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
+import org.eclipse.paho.client.mqttv3.MqttException;
+import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class MqttConsumerConfig {
+  @Value("${spring.mqtt.username}")
+  private String username;
+
+  @Value("${spring.mqtt.password}")
+  private String password;
+
+  @Value("${spring.mqtt.url}")
+  private String hostUrl;
+
+  @Value("${spring.mqtt.client.id}")
+  private String clientId;
+
+  @Value("${spring.mqtt.default.topic}")
+  private String defaultTopic;
+
+  private MqttClient client;
+
+  @PostConstruct
+  public void init() {
+    connect();
+  }
+
+  public void connect() {
+    try {
+      // Create a client instance
+      client = new MqttClient(hostUrl, clientId, new MemoryPersistence());
+      // Create a connection option object
+      MqttConnectOptions options = new MqttConnectOptions();
+      // set connection option
+      options.setCleanSession(true);
+      options.setUserName(username);
+      options.setPassword(password.toCharArray());
+      options.setConnectionTimeout(100);
+      options.setKeepAliveInterval(20);
+      options.setWill("willTopic", (clientId + "Disconnected").getBytes(), 0, false);
+      client.setCallback(new MqttConsumerCallBack());
+      System.out.println("Start Connection");
+      client.connect(options);
+      System.out.println("End Connection");
+      int[] qos = { 1, 1 };
+      // Topics
+      String[] topics = { "topic1", "topic2" };
+      client.subscribe(topics, qos);
+    } catch (MqttException e) {
+      e.printStackTrace();
+    }
+  }
+
+  public void disConnect() {
+    try {
+      client.disconnect();
+    } catch (MqttException e) {
+      e.printStackTrace();
+    }
+  }
+
+  public void subscribe(String topic, int qos) {
+    try {
+      client.subscribe(topic, qos);
+    } catch (MqttException e) {
+      e.printStackTrace();
+    }
+  }
+}

src/main/java/com/ffii/towngas/sensor/web/TestController.java

@@ -0,0 +1,38 @@
+package com.ffii.towngas.sensor.web;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.ffii.core.support.AbstractController;
+import com.ffii.towngas.config.MqttConsumerConfig;
+
+@RestController
+@RequestMapping("/protected/sensorData")
+public class TestController extends AbstractController {
+
+  @Value("${spring.mqtt.client.id}")
+  private String clientId;
+
+  private MqttConsumerConfig client;
+
+  public TestController(MqttConsumerConfig client) {
+    this.client = client;
+  }
+
+  @RequestMapping("connect")
+  @ResponseBody
+  public String connect() {
+    client.connect();
+    return clientId + "Connected to the server";
+  }
+
+  @RequestMapping("dis-connect")
+  @ResponseBody
+  public String disConnect() {
+    client.disConnect();
+    return clientId + "Disconnected from the server";
+  }
+
+}

src/main/resources/application-db-238.yml

@@ -0,0 +1,5 @@
+spring:
+  datasource:
+    url: jdbc:mysql://192.168.1.238:3306/towngasdb?useUnicode=true&characterEncoding=UTF8&serverTimezone=GMT%2B8
+    username: root
+    password: secret

src/main/resources/application-mqtt-config.yml

@@ -0,0 +1,9 @@
+spring:
+  mqtt:
+    url: tcp://202.130.68.18:1883
+    username: test
+    password: q1w2e3r4
+    client:
+      id: cfghiftghigyui
+    default:
+      topic: topic