Java 如何在HiveMQ客户端中打印所有主题？（MQTT）

是否有方法打印HiveMQ代理存储的所有主题？我想打印出客户端连接到的所有主题，以便在HiveMQ客户端的主类中进行测试。我为HiveMQ客户端和社区（代理）留下了链接

HiveMQ：

HiveMQ客户端的my main类中的代码：

package com.main;

import java.util.UUID;

import com.hivemq.client.mqtt.MqttGlobalPublishFilter;
import com.hivemq.client.mqtt.datatypes.MqttQos;
import com.hivemq.client.mqtt.mqtt5.Mqtt5BlockingClient;
import com.hivemq.client.mqtt.mqtt5.Mqtt5BlockingClient.Mqtt5Publishes;
import com.hivemq.client.mqtt.mqtt5.Mqtt5Client;
import com.hivemq.client.mqtt.mqtt5.message.publish.Mqtt5Publish;
import java.util.logging.Logger;
import java.util.NoSuchElementException;

import java.util.logging.Level;
import java.util.concurrent.TimeUnit;


public class Main {

    private static final Logger LOGGER = Logger.getLogger(Main.class.getName());  // Creates a logger instance 


    public static void main(String[] args) {

                Mqtt5BlockingClient client1 = Mqtt5Client.builder()
            .identifier(UUID.randomUUID().toString()) // the unique identifier of the MQTT client. The ID is randomly generated between 
            .serverHost("localhost")  // the host name or IP address of the MQTT server. Kept it 0.0.0.0 for testing. localhost is default if not specified.
            .serverPort(1883)  // specifies the port of the server
            .buildBlocking();  // creates the client builder

            client1.connect();  // connects the client
            System.out.println("Client1 Connected");
            System.out.println(client1.toString());


            String testmessage = "How is it going!";
            byte[] messagebytesend = testmessage.getBytes();   // stores a message as a byte array to be used in the payload 

    try {  

        Mqtt5Publishes publishes = client1.publishes(MqttGlobalPublishFilter.ALL);  // creates a "publishes" instance thats used to queue incoming messages

            client1.subscribeWith()  // creates a subscription 
            .topicFilter("test1/#")  // filters to receive messages only on this topic (# = Multilevel wild card, + = single level wild card)
            .qos(MqttQos.AT_LEAST_ONCE)  // Sets the QoS to 2 (At least once) 
            .send(); 
            System.out.println("The client1 has subscribed");


            client1.publishWith()  // publishes the message to the subscribed topic 
            .topic("test/pancakes/topic")   // publishes to the specified topic
            .qos(MqttQos.AT_LEAST_ONCE)  
            .payload(messagebytesend)  // the contents of the message 
            .send();
            System.out.println("The client1 has published");


            Mqtt5Publish receivedMessage = publishes.receive(5,TimeUnit.SECONDS).get(); // receives the message using the "publishes" instance waiting up to 5 seconds                                                                          // .get() returns the object if available or throws a NoSuchElementException 


         byte[] tempdata = receivedMessage.getPayloadAsBytes();    // converts the "Optional" type message to a byte array 
         System.out.println();
         String getdata = new String(tempdata); // converts the byte array to a String 
         System.out.println(getdata);


    }

    catch (InterruptedException e) {    // Catches interruptions in the thread 
        LOGGER.log(Level.SEVERE, "The thread was interrupted while waiting for a message to be received", e);
        }

    catch (NoSuchElementException e){
        System.out.println("There are no received messages");   // Handles when a publish instance has no messages 
    }

    client1.disconnect();  
    System.out.println("Client1 Disconnected");

    }

}

是否有方法打印HiveMQ代理拥有的所有主题 储存的

不，MQTT中没有“给我一个代理中所有主题的列表”这样的东西

您的代码可以订阅所有“活动”主题，但这意味着您将捕获所有主题，除非您让代码在数月或数年内7/24运行

只需将订阅更改为以下内容：

client1.subscribeWith().topicFilter("#")

---

现在，您的代码将获得发布者发布到的所有“活动”主题的消息。预先警告一下，您的代码每秒可能会收到数千条消息，其中许多消息可能是针对同一主题的。因此，您需要过滤掉这些内容。

好的，但我想知道是否有一种方法可以轻松打印出特定客户订阅的所有主题？而不是从客户的角度。