Java 无法从Vert.x MQTT服务器接收消息

我试图让一些基于Paho的客户机与Vert.x MQTT服务器一起工作。我正试图发布到接收客户端订阅的测试主题。我很难从我的客户端发布者向我的客户端订阅者发送消息

使用我在互联网上看到的真实示例，我构建了一个MQTT代理。Vert.x MQTT代理代码的代码如下：

public class MQTTBroker
{      
   public MQTTBroker()
   {
      MqttServerOptions opts = new MqttServerOptions();
      opts.setHost("localhost");
      opts.setPort(1883);

      MqttServer server = MqttServer.create(Vertx.vertx(),opts);

      server.endpointHandler(endpoint -> {
      System.out.println("MQTT client [" + endpoint.clientIdentifier() + "] request to connect, clean session = " + endpoint.isCleanSession());
      endpoint.accept(false);

      if("Test_Send".equals(endpoint.clientIdentifier()))
      {
         doPublish(endpoint);

         handleClientDisconnect(endpoint);
      }
      else
      {
          handleSubscription(endpoint);
          handleUnsubscription(endpoint);
          handleClientDisconnect(endpoint);
      }
     }).listen(ar -> {
      if (ar.succeeded()) {
           System.out.println("MQTT server is listening on port " + ar.result().actualPort());
       } else {
           System.out.println("Error on starting the server");
           ar.cause().printStackTrace();
       }
   });
 }

  protected void handleSubscription(MqttEndpoint endpoint) {
     endpoint.subscribeHandler(subscribe -> {
         List grantedQosLevels = new ArrayList < > ();
         for (MqttTopicSubscription s: subscribe.topicSubscriptions()) {
             System.out.println("Subscription for " + s.topicName() + " with QoS " + s.qualityOfService());
             grantedQosLevels.add(s.qualityOfService());
        }
        endpoint.subscribeAcknowledge(subscribe.messageId(), grantedQosLevels);
    });
}

protected void handleUnsubscription(MqttEndpoint endpoint) {
    endpoint.unsubscribeHandler(unsubscribe -> {
        for (String t: unsubscribe.topics()) {
            System.out.println("Unsubscription for " + t);
        }
        endpoint.unsubscribeAcknowledge(unsubscribe.messageId());
    });
}

protected void publishHandler(MqttEndpoint endpoint) {
     endpoint.publishHandler(message -> {
     endpoint.publishAcknowledge(message.messageId());
     }).publishReleaseHandler(messageId -> {
         endpoint.publishComplete(messageId);
     });
 }

protected void handleClientDisconnect(MqttEndpoint endpoint) {
    endpoint.disconnectHandler(h -> {
        System.out.println("The remote client has closed the connection.");
    });
}

protected void doPublish(MqttEndpoint endpoint) {

   // just as example, publish a message with QoS level 2
   endpoint.publish("Test_Topic",
     Buffer.buffer("Hello from the Vert.x MQTT server"),
     MqttQoS.EXACTLY_ONCE,
     false,
     false);
   publishHandler(endpoint);

   // specifing handlers for handling QoS 1 and 2
   endpoint.publishAcknowledgeHandler(messageId -> {

     System.out.println("Received ack for message = " +  messageId);

   }).publishReceivedHandler(messageId -> {

     endpoint.publishRelease(messageId);

   }).publishCompleteHandler(messageId -> {

     System.out.println("Received ack for message = " +  messageId);
   });
  }
}

public class Receiver implements MqttCallback
{

   public Receiver()
   {     
      MqttClient client = null;

      try
      {
         MemoryPersistence persist = new MemoryPersistence(); 
         client = new MqttClient("tcp://localhost:1883",persist);
         client.setCallback(this);
         client.connect();
         client.subscribe("Test_Topic");
         System.out.println("The receiver is initialized.");
      }
      catch(Exception exe)
      {
         exe.printStackTrace();
      }
   }

   @Override
   public void connectionLost(Throwable arg0)
   {
      System.out.println("Connection is lost!");
   }

   @Override
   public void deliveryComplete(IMqttDeliveryToken arg0)
   {
      System.out.println("Delivered!");
   }

    @Override
   public void messageArrived(String theStr, MqttMessage theMsg)
   {
     System.out.println("Message from: "+theStr);

      try
      {
         String str = new String(theMsg.getPayload());
         System.out.println("Message is: "+str); 
      }
      catch(Exception exe)
      {
         exe.printStackTrace();
      }

   }

 }

public void publish(String theMsg)
{
   MqttClient nwclient = null;

   try
  {
      ServConfigurator serv = ServConfigurator.getInstance();
      MemoryPersistence persist = new MemoryPersistence(); 
      String url = "tcp://localhost:1883";

      nwclient = new MqttClient(url,"Test_Send",persist);

      MqttConnectOptions option = new MqttConnectOptions();
      option.setCleanSession(true);

      nwclient.connect(option);

      MqttMessage message = new MqttMessage(theMsg.getBytes());
      message.setQos(2);
      nwclient.publish("Test_Topic",message);

      nwclient.disconnect();
      nwclient.close();

   }
   catch(Exception exe)
   {
       exe.printStackTrace();
   }
}

订阅者和发布者是本地的，但一旦我部署应用程序，它们可以（并且将）远离代理。我用于发布的基于泛美卫生组织的代码如下：

public class MQTTBroker
{      
   public MQTTBroker()
   {
      MqttServerOptions opts = new MqttServerOptions();
      opts.setHost("localhost");
      opts.setPort(1883);

      MqttServer server = MqttServer.create(Vertx.vertx(),opts);

      server.endpointHandler(endpoint -> {
      System.out.println("MQTT client [" + endpoint.clientIdentifier() + "] request to connect, clean session = " + endpoint.isCleanSession());
      endpoint.accept(false);

      if("Test_Send".equals(endpoint.clientIdentifier()))
      {
         doPublish(endpoint);

         handleClientDisconnect(endpoint);
      }
      else
      {
          handleSubscription(endpoint);
          handleUnsubscription(endpoint);
          handleClientDisconnect(endpoint);
      }
     }).listen(ar -> {
      if (ar.succeeded()) {
           System.out.println("MQTT server is listening on port " + ar.result().actualPort());
       } else {
           System.out.println("Error on starting the server");
           ar.cause().printStackTrace();
       }
   });
 }

  protected void handleSubscription(MqttEndpoint endpoint) {
     endpoint.subscribeHandler(subscribe -> {
         List grantedQosLevels = new ArrayList < > ();
         for (MqttTopicSubscription s: subscribe.topicSubscriptions()) {
             System.out.println("Subscription for " + s.topicName() + " with QoS " + s.qualityOfService());
             grantedQosLevels.add(s.qualityOfService());
        }
        endpoint.subscribeAcknowledge(subscribe.messageId(), grantedQosLevels);
    });
}

protected void handleUnsubscription(MqttEndpoint endpoint) {
    endpoint.unsubscribeHandler(unsubscribe -> {
        for (String t: unsubscribe.topics()) {
            System.out.println("Unsubscription for " + t);
        }
        endpoint.unsubscribeAcknowledge(unsubscribe.messageId());
    });
}

protected void publishHandler(MqttEndpoint endpoint) {
     endpoint.publishHandler(message -> {
     endpoint.publishAcknowledge(message.messageId());
     }).publishReleaseHandler(messageId -> {
         endpoint.publishComplete(messageId);
     });
 }

protected void handleClientDisconnect(MqttEndpoint endpoint) {
    endpoint.disconnectHandler(h -> {
        System.out.println("The remote client has closed the connection.");
    });
}

protected void doPublish(MqttEndpoint endpoint) {

   // just as example, publish a message with QoS level 2
   endpoint.publish("Test_Topic",
     Buffer.buffer("Hello from the Vert.x MQTT server"),
     MqttQoS.EXACTLY_ONCE,
     false,
     false);
   publishHandler(endpoint);

   // specifing handlers for handling QoS 1 and 2
   endpoint.publishAcknowledgeHandler(messageId -> {

     System.out.println("Received ack for message = " +  messageId);

   }).publishReceivedHandler(messageId -> {

     endpoint.publishRelease(messageId);

   }).publishCompleteHandler(messageId -> {

     System.out.println("Received ack for message = " +  messageId);
   });
  }
}

public class Receiver implements MqttCallback
{

   public Receiver()
   {     
      MqttClient client = null;

      try
      {
         MemoryPersistence persist = new MemoryPersistence(); 
         client = new MqttClient("tcp://localhost:1883",persist);
         client.setCallback(this);
         client.connect();
         client.subscribe("Test_Topic");
         System.out.println("The receiver is initialized.");
      }
      catch(Exception exe)
      {
         exe.printStackTrace();
      }
   }

   @Override
   public void connectionLost(Throwable arg0)
   {
      System.out.println("Connection is lost!");
   }

   @Override
   public void deliveryComplete(IMqttDeliveryToken arg0)
   {
      System.out.println("Delivered!");
   }

    @Override
   public void messageArrived(String theStr, MqttMessage theMsg)
   {
     System.out.println("Message from: "+theStr);

      try
      {
         String str = new String(theMsg.getPayload());
         System.out.println("Message is: "+str); 
      }
      catch(Exception exe)
      {
         exe.printStackTrace();
      }

   }

 }

public void publish(String theMsg)
{
   MqttClient nwclient = null;

   try
  {
      ServConfigurator serv = ServConfigurator.getInstance();
      MemoryPersistence persist = new MemoryPersistence(); 
      String url = "tcp://localhost:1883";

      nwclient = new MqttClient(url,"Test_Send",persist);

      MqttConnectOptions option = new MqttConnectOptions();
      option.setCleanSession(true);

      nwclient.connect(option);

      MqttMessage message = new MqttMessage(theMsg.getBytes());
      message.setQos(2);
      nwclient.publish("Test_Topic",message);

      nwclient.disconnect();
      nwclient.close();

   }
   catch(Exception exe)
   {
       exe.printStackTrace();
   }
}

请注意，我正在从代理发布一个硬编码字符串（用于测试目的）（如doPublish方法中所示），但应该注意的是，我正在捕获发布服务器客户端在端点处理程序中发布的尝试。不幸的是，虽然将订阅者和发布者连接到代理没有问题，但由于某些原因，消息没有到达订阅者。我尝试了各种方法，但是当发布者客户端实际发布到代理时，由于某种原因，代理的发布无法将字符串发送到订阅者

我很确定我在这里错过了什么，但我想不出会是什么。有人能帮我把这件事做好吗

---

提前感谢您提供的任何帮助或见解。

当MQTT服务器收到来自发布服务器的消息，以便调用endpoint.publishHandler将消息传递给它时，我看不到您的代码中有任何逻辑来获取主题并搜索为该主题注册的订阅者（端点）并向他们发送消息。 同时，我并没有看到你们在订阅者端点和订阅主题之间以某种方式保存引用来进行上述研究。

---

请记住，MQTT服务器不是一个代理，它不会为您处理主题上订阅的客户机列表；你可以在上面建立一个经纪人，这应该是你正在尝试做的事情？

事实证明，你是对的。我组装了一个服务器，并认为我在使用一个代理。这实际上是一件好事，因为我可以让经纪人做任何我想要的事情。我现在让我的客户接收消息，并将建立一个很好的定制基础设施。谢谢你的洞察力。