使用 ActiveMQ 取消订阅持久订阅者

Question

我正在尝试取消订阅 TOPICS 的持久订阅者。

我的应用是一种社交网络：每个用户都是其他用户的话题。因此，每次用户在做某事时，都会通知他的朋友。当然，订阅者可能会取消订阅某个主题，不想再收到有关用户的通知。

每次我尝试取消订阅某个主题的订阅者时，都会收到一条错误消息，告诉我：“javax.jms.JMSException: Durable consumer is in use”

这是我的 2 个类，SENDER 一个和 RECEIVER 一个。谁能告诉我我做错了什么？？

SENDER 类：

package com.citizenweb.classes;

import java.util.Date;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageFormatException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.jms.Topic;
import javax.jms.ObjectMessage;
import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;

import com.citizenweb.interfaces.PostIF;
import com.citizenweb.interfaces.UserIF;

public class Sender {

    private ActiveMQConnectionFactory factory = null;
    private ActiveMQConnection connection = null;
    private ActiveMQSession session = null;
    private Destination destination = null;
    private MessageProducer producer = null;

    public Sender() {
    }

    public void connect(){
        try{
            factory = new ActiveMQConnectionFactory(ActiveMQConnection.DEFAULT_BROKER_URL);
            // TODO Mécanisme de sécurité d'ActiveMQ à rétablir en production
            factory.setTrustAllPackages(true);
            connection = (ActiveMQConnection) factory.createConnection();
            connection.start();
            session = (ActiveMQSession) connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        } catch (JMSException e){
            e.printStackTrace();
        }
    }

    public void sendPost(UserIF user,PostIF post) {
        if(session==null){connect();}
        try {
            destination = session.createTopic(user.toString());
            producer = session.createProducer(destination);
            ObjectMessage postMessage = session.createObjectMessage();
            postMessage.setObject(post);
            producer.send(postMessage);
            System.out.println("\n SENDER Object message sent");



        } catch (MessageFormatException e) {
            e.printStackTrace();
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public void sendInformation(UserIF user,String info){
        if(session==null){connect();}
        try {
            destination = session.createTopic(user.toString());
            producer = session.createProducer(destination);
            TextMessage infoMessage = session.createTextMessage();
            infoMessage.setText(info);
            producer.send(infoMessage);
            System.out.println("\n SENDER Information message sent");
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {

        UserIF u1, u2, u3;
        String[] nom = new String[5];
        String[] prenom = new String[5];
        String[] login = new String[5];
        String[] password = new String[5];
        Date[] naiss = new Date[5];
        String[] mail = new String[5];
        for (int i = 0; i < 5; i++) {
            nom[i] = "nom_" + i;
            prenom[i] = "prenom_" + i;
            login[i] = "login_" + i;
            password[i] = "password_" + i;
            naiss[i] = new Date();
            mail[i] = "mail_" + i;
        }

        System.out.println("\n SENDER AFFECTATION DES NOMS");
        u1 = new User(nom[0], prenom[0], login[0], password[0], naiss[0], mail[0]);
        u2 = new User(nom[1], prenom[1], login[1], password[1], naiss[1], mail[1]);
        u3 = new User(nom[2], prenom[2], login[2], password[2], naiss[2], mail[2]);


        Sender sender = new Sender();

        sender.sendInformation(u1, "U1 notification");
        sender.sendInformation(u2, "U2 notification");
        sender.sendInformation(u3, "U3 notification");
        //PostIF post = new Post("Mon Post","Ceci est mon message",u1,u1,"Classe Sender",((User) u1).getIdUser(),0);
        //sender.sendPost(user, post);
        sender.session.close();
        sender.connection.close();

    }

}

接收器类：

package com.citizenweb.classes;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.ObjectMessage;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.jms.Topic;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.broker.region.Destination;
import com.citizenweb.interfaces.PostIF;
import com.citizenweb.interfaces.UserIF;
import com.citizenweb.classes.Post;

public class Receiver implements MessageListener, Serializable {

    private static final long serialVersionUID = 1L;
    private ActiveMQConnectionFactory factory = null;
    private ActiveMQConnection connection = null;
    private ActiveMQSession session = null;
    private Topic destination = null;
    private MessageConsumer consumer = null;

    UserIF userTopic = new User();
    UserIF userSubscriber = new User();
    List<Message> listeMsg = new ArrayList<Message>();

    public Receiver(UserIF subscriber) {
        this.userSubscriber = subscriber;
    }

    public void connect() {
        try {
            factory = new ActiveMQConnectionFactory(ActiveMQConnection.DEFAULT_BROKER_URL);
            // TODO Mécanisme de sécurité d'ActiveMQ à rétablir en production
            factory.setTrustAllPackages(true);
            connection = (ActiveMQConnection) factory.createConnection();
            // ClientID :
            // https://qnalist.com/questions/2068823/create-durable-topic-subscriber
            connection.setClientID(userSubscriber.toString());
            connection.start();
            session = (ActiveMQSession) connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public void receiveMessage(UserIF topic) {
        try {
            if (session == null) {
                connect();
            }
            destination = session.createTopic(topic.toString());
            String nomAbonnement = topic.toString() + "->" + userSubscriber.toString();
            //String nomAbonnement = userSubscriber.toString();
            consumer = session.createDurableSubscriber(destination, nomAbonnement);
            consumer.setMessageListener(this);
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public void unsubscribe(UserIF topic) {
        try {
            if (session == null) {
                connect();
            }
            System.out.println("\n RECEIVER Désinscription du topic " + topic.toString());
            //consumer.close();
            String nomAbonnement = topic.toString() + "->" + userSubscriber.toString();
            //String nomAbonnement = userSubscriber.toString();
            System.out.println("\n RECEIVER Abonnement à clore = " + nomAbonnement);
            session.unsubscribe(nomAbonnement);
            System.out.println("\n RECEIVER " + userSubscriber.toString() + " s'est désinscrit de " + nomAbonnement);
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onMessage(Message message) {
        System.out.println("\n RECEIVER OnMessage triggered for " + userSubscriber.toString());
        listeMsg.add(message);
        System.out.println("\n RECEIVER Nombre de messages reçus par " + userSubscriber + " = " + listeMsg.size());
        String classe = message.getClass().getSimpleName();
        System.out.println("\n RECEIVER Classe de message : " + classe);
        try {
            if (message instanceof TextMessage) {
                TextMessage text = (TextMessage) message;
                System.out.println("\n RECEIVER Information : " + text.getText());
            }
            if (message instanceof ObjectMessage) {
                System.out.println("\n RECEIVER ObjectMessage");
                ObjectMessage oMessage = (ObjectMessage) message;
                if (oMessage.getObject() instanceof PostIF) {
                    PostIF post = (PostIF) oMessage.getObject();
                    String s = ((Post) post).getCorpsMessage();
                    System.out.println("\n RECEIVER Post : " + s);
                }
            }
        } catch (JMSException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws JMSException {

        /*
         * EACH USER IS A TOPIC FOR OTHER USERS
         * WHATEVER A USER DOES RESULTS IN A NOTIFICATION TO SUBSCRIBERS
        */

        //CREATE USER
        UserIF u1, u2, u3;
        String[] nom = new String[5];
        String[] prenom = new String[5];
        String[] login = new String[5];
        String[] password = new String[5];
        Date[] naiss = new Date[5];
        String[] mail = new String[5];
        for (int i = 0; i < 5; i++) {
            nom[i] = "nom_" + i;
            prenom[i] = "prenom_" + i;
            login[i] = "login_" + i;
            password[i] = "password_" + i;
            naiss[i] = new Date();
            mail[i] = "mail_" + i;
        }

        u1 = new User(nom[0], prenom[0], login[0], password[0], naiss[0], mail[0]);
        u2 = new User(nom[1], prenom[1], login[1], password[1], naiss[1], mail[1]);
        u3 = new User(nom[2], prenom[2], login[2], password[2], naiss[2], mail[2]);

        /*
         * MAKE EACH USER A SUBSCRIBER
         */
        Receiver receiver1 = new Receiver(u1);
        Receiver receiver2 = new Receiver(u2);
        Receiver receiver3 = new Receiver(u3);

        /*
         * PUT A MESSAGE LISTENER FOR EACH USER
         */
        receiver1.receiveMessage(u2);
        receiver1.receiveMessage(u3);
        receiver2.receiveMessage(u1);
        receiver2.receiveMessage(u3);
        receiver3.receiveMessage(u1);
        receiver3.receiveMessage(u2);

        /*
         * CALL THE SENDER CLASS TO SEND MESSAGES
         */
        try {
            Sender.main(args);
        } catch (Exception e1) {
            e1.printStackTrace();
        }

        /*
         * A SLEEP TO HAVE ENOUGH TIME TO LOOK AT THE ACTIVEMQ CONSOLE
         * CAN BE REMOVE
         */
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return;
        }

        /*
         * UNSUBSCRIBE SUBSCRIBERS FROM TOPICS
         */
        receiver1.unsubscribe(u2);
        receiver1.unsubscribe(u3);
        receiver2.unsubscribe(u1);
        receiver2.unsubscribe(u3);
        receiver3.unsubscribe(u1);
        receiver3.unsubscribe(u2);
    }

}

Answer 1

如果当前没有活动订阅者正在使用它，您只能取消订阅持久订阅。看起来您的代码创建了多个订阅并且不会停止消费者，因此取消订阅当然会失败，如果您关闭消费者然后取消订阅，您应该会得到您正在寻找的结果。

持久订阅取消订阅的一个例子是here。

Answer 2

每个连接都需要唯一的 ClientID：connection.setClientID("clientID");

我的错误是误解了给定客户的这种独特性。

当客户端订阅一个 Topic 时，该 Topic 有一个连接。因此，对于订阅 3 个主题的给定客户端（例如），需要 3 个 ClientID，因为需要 3 个连接。 ClientID 必须是唯一的，因为它为一个主题标识了一个客户端的一个连接。

这就是为什么当我想结束订阅时，有这么多JMSException 告诉我“正在使用耐用消费者”。