package com.sb.mqtt;
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MqttTest {
    public static void main(String[] args) {
        // 1. 基础配置
        String subTopic = "testtopic/#";       // 订阅主题（通配符，匹配 testtopic/1、testtopic/2 等）
        String pubTopic = "testtopic/1";       // 发布主题
        String content = "Hello World 2026";       // 消息内容
        int qos = 2;                           // 服务质量：0最多一次，1至少一次，2 exactly once
        String broker = "tcp://192.168.91.165:9610";// MQTT Broker 地址
        String clientId = "admin_" + System.currentTimeMillis(); // 客户端ID（必须全局唯一）  admin_   emqx_test_
        MemoryPersistence persistence = new MemoryPersistence(); // 内存持久化（生产环境可改用文件持久化）
        try {
            // 2. 创建 MQTT 客户端实例
            MqttClient client = new MqttClient(broker, clientId, persistence);
            // 3. 配置连接选项
            MqttConnectOptions connOpts = new MqttConnectOptions();
            connOpts.setUserName("admin");                  // 用户名  emqx_test admin
            connOpts.setPassword("public".toCharArray()); // 密码  emqx_test_password    public
            connOpts.setCleanSession(true);                     // 清除会话：true=不保留离线消息，false=保留
            connOpts.setConnectionTimeout(10);                   // 连接超时时间（秒）
            connOpts.setKeepAliveInterval(60);                  // 心跳间隔（秒）
            // 4. 设置回调函数（核心：处理连接丢失、消息接收、消息送达）
            client.setCallback(new MqttCallback() {
                /**
                 * 连接丢失时触发（如网络断开、Broker 宕机）
                 */
                @Override
                public void connectionLost(Throwable cause) {
                    System.out.println("连接断开，可做重连：" + cause.getMessage());
                    // 生产环境：在此处实现自动重连逻辑
                }
                /**
                 * 订阅主题收到消息时触发
                 */
                @Override
                public void messageArrived(String topic, MqttMessage message) throws Exception {
                    System.out.println("=====================================");
                    System.out.println("接收消息主题: " + topic);
                    System.out.println("接收消息Qos: " + message.getQos());
                    System.out.println("接收消息内容: " + new String(message.getPayload()));
                    System.out.println("=====================================");
                }
                /**
                 * 消息发布完成时触发（仅 QoS 1/2 有效）
                 */
                @Override
                public void deliveryComplete(IMqttDeliveryToken token) {
                    System.out.println("deliveryComplete---------" + token.isComplete());
                }
            });
            // 5. 建立连接
            System.out.println("Connecting to broker: " + broker);
            client.connect(connOpts);
            System.out.println("Connected");
            // 6. 订阅主题
            System.out.println("Subscribing to topic: " + subTopic);
            client.subscribe(subTopic, qos);
            System.out.println("Subscribed");
            // 7. 发布消息
            System.out.println("Publishing message: " + content);
            MqttMessage message = new MqttMessage(content.getBytes());
            message.setQos(qos);
            message.setRetained(false); // 保留消息：false=不持久化，true=Broker 存储，新订阅者立即收到
            client.publish(pubTopic, message);
            System.out.println("Message published");
            // 8. 等待消息接收（测试用，生产环境不要主动断开）
            Thread.sleep(2000);
            // 9. 断开连接、关闭资源
            client.disconnect();
            System.out.println("Disconnected");
            client.close();
            System.exit(0);
        } catch (MqttException me) {
            // 异常处理
            System.out.println("reason " + me.getReasonCode());
            System.out.println("msg " + me.getMessage());
            System.out.println("loc " + me.getLocalizedMessage());
            System.out.println("cause " + me.getCause());
            System.out.println("excep " + me);
            me.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

Connecting to broker: tcp://192.168.91.165:9610
Connected
Subscribing to topic: testtopic/#
Subscribed
Publishing message: Hello World 2026
Message published
deliveryComplete---------true
=====================================
接收消息主题: testtopic/1
接收消息Qos: 2
接收消息内容: Hello World 2026
=====================================
Disconnected