无法连接到MQTT服务器：“原因代码：5-无权执行请求的操作”

Question

• 任务：将“ Hello world”发送到服务器进行测试。
• 服务器：clouldMQTT。
• 库：PahoMQTT。
• 原因码：5-无权执行请求的操作。
• 原因：空。
• 消息代码：无连接权限。

• 代码：

  String topic    = "Lesson_MQTT_server";
  String broker   = "tcp://m15.cloudmqtt.com:18594";
  char [] pass    = "qmaoaTfDebag".toCharArray(); // Fake pass
  String userId   = "oelmanhl";
  String content  = "Hello world!";
  int qos         = 0;
  
  
  try {
      MqttClient client = new MqttClient (broker, userId, new MemoryPersistence());
      MqttConnectOptions options = new MqttConnectOptions ();
      options.setAutomaticReconnect(true);
      options.setCleanSession(true);
      options.setPassword(pass);          
      System.out.println ("Connecting..."); 
  
      client.connect(options); 
      System.out.println ("Conntected!");
  
      MqttMessage message = new MqttMessage ();
      message.clearPayload();
      message.setPayload(content.getBytes());
      message.setQos(qos);
      System.out.println ("Publishing message...");
  
      client.publish(topic, message);
      System.out.println ("Message published!");
  
      client.disconnect();
      System.out.println ("Disconect!");
  
  } catch (MqttException ex) {
      System.out.println ("Reason code: " + ex.getReasonCode());
      System.out.println ("Cause code: " + ex.getCause());
      System.out.println ("Message code: " + ex.getMessage());
  }