Java SDK

package com.tencenttdmq.mqtt.demo;

import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallbackExtended;
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.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import java.nio.charset.StandardCharsets;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.util.concurrent.TimeUnit;

public class QuickStartTls {

    public static SSLSocketFactory buildSSLSocketFactory() throws NoSuchAlgorithmException, KeyManagementException {
        SSLContext ctx = SSLContext.getInstance("TLS");
        ctx.init(null, null, null);
        return ctx.getSocketFactory();
    }

    public static void main(String[] args) throws MqttException, InterruptedException, NoSuchAlgorithmException, KeyManagementException {

        // 从MQTT控制台获取接入点:
        // 通过Private Link实现VPC网络打通的用户, 使用内网接入点;
        // 通过公网访问的用户, 确保公网安全策略允许, 程序运行机器有公网接入;
        String serverUri = "ssl://mqtt-xxxx.mqtt.tencenttdmq.com:8883";
        
        // 合法的Client Identifier包含 数字0-9, 小写英文字母a-z, 以及大写英文字母A-Z, 总长度为1-23个字符
        // 参考 https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901059
        String clientId = "ClientQuickStartTls";

        // 在控制台 --> 认证 Tab页创建账户, 复制用户名和密码
        String username = "YOUR_USERNAME";
        String password = "YOUR_PASSWORD";

        // 确认一级主题 "home" 在MQTT控制台已经创建
        String topic = "home/test";

        String[] topicFilters = new String[]{"home/test"};
        int[] qos = new int[]{1};

        int total = 16;

        try (MqttClient client = new MqttClient(serverUri, clientId, new MemoryPersistence())) {
            client.setTimeToWait(3000);
            MqttConnectOptions options = new MqttConnectOptions();
            options.setUserName(username);
            options.setPassword(password.toCharArray());
            options.setSocketFactory(buildSSLSocketFactory());
            options.setHttpsHostnameVerificationEnabled(false);
            options.setMqttVersion(MqttConnectOptions.MQTT_VERSION_3_1_1);
            options.setCleanSession(true);
            options.setAutomaticReconnect(true);
            client.connect(options);

            client.setCallback(new MqttCallback(client, topicFilters, qos));

            for (int i = 0; i < total; i++) {
                String msg = "Hello MQTT " + i;
                MqttMessage message = new MqttMessage(msg.getBytes());
                message.setQos(1);
                System.out.printf("Prepare to publish message %d%n", i);
                client.publish(topic, message);
                System.out.printf("Published message %d%n", i);
                TimeUnit.SECONDS.sleep(1);
            }

            TimeUnit.SECONDS.sleep(3);

            client.disconnect();
        }
    }

    static class MqttCallback implements MqttCallbackExtended {

        private final MqttClient client;

        private final String[] topicFilters;
        private final int[] qos;

        public MqttCallback(MqttClient client, String[] topicFilters, int[] qos) {
            this.client = client;
            this.topicFilters = topicFilters;
            this.qos = qos;
        }

        public void messageArrived(String topic, MqttMessage message) {
            System.out.printf("Message arrived, topic=%s, QoS=%d content=[%s]%n", topic, message.getQos(),
                    new String(message.getPayload(), StandardCharsets.UTF_8));
        }

        public void connectionLost(Throwable cause) {
            System.out.println("connectionLost: " + cause.getMessage());
        }

        @Override
        public void connectComplete(boolean reconnect, String serverURI) {
            System.out.println(reconnect ? "Reconnected" : "Connect" + serverURI);
            try {
                client.subscribe(topicFilters, qos);
                System.out.printf("Subscribed %d topics%n", topicFilters.length);
            } catch (MqttException e) {
                e.printStackTrace();
            }
        }

        public void deliveryComplete(IMqttDeliveryToken token) {
            System.out.printf("Delivery completed: packet-id=%d%n", token.getMessageId());
        }
    }
}