activemq点对点发送 mqtt 点对点发送消息

转载

mob64ca13fbd761 2024-03-07 14:35:32

文章标签 activemq点对点发送 java activemq mqtt 发布订阅 文章分类 机器学习人工智能

使用语言：java
消息中间件：activemq
用到工具：git、maven、任意文本编辑器

1、使用git下载activemq源码
git clone https://git-wip-us.apache.org/repos/asf/activemq.git
2、git自动下载最新版本的源码，需要下载和你使用的mq程序对应的版本，上一步的网址中有tag一栏，选择对应的版本进去，查看对应的commit所产生的hashcode
git reset –hard <对应版本hashcode>
3、自定义消息到topic后推送给订阅者的消息分发策略
策略存放路径在项目根路径下的\activemq-broker\src\main\java\org\apache\activemq\broker\region\policy\
在此目录下随便选一个原有的*Policy.java文件，修改此文件内容
4、重新编译broker
在\activemq-broker\下执行mvn package进行打包（打包后的内容应该在target文件夹中）
把生成的activemq-broker-version.jar拷贝到使用的mq程序的lib目录下
5、修改activemq的配置文件

接下来就是实现点对点的重点，自定义分发策略
1、点对点的实现是通过设置clientId来确定两个点，因为MQTT框架无法设置message的properties属性，所以把clientId放到消息体中，用某个特殊符号隔开，我这里用的是@符号
2、producer.send(message);发送消息后到达topic中，如果此topic有订阅的消费者，那么才会进入到分发策略，而进入到哪个分发策略是你在第五步配置的\conf\activemq.xml中指定的那个，配置文件更改后就会进入到下面的策略中。
3、分发策略中定义，必须是在名为.ptp结尾的topic中才会进行点对点推送，不然就和正常的一样一对多的推送

String msgBody = "message body";
String clientId = "mqtt-1012";
producer.send(clientId+"@"+msgBody);

package org.apache.activemq.broker.region.policy;

import java.util.List;

import org.apache.activemq.broker.region.MessageReference;
import org.apache.activemq.broker.region.Subscription;
import org.apache.activemq.command.ActiveMQDestination;
import org.apache.activemq.filter.MessageEvaluationContext;

public class PriorityDispatchPolicy extends SimpleDispatchPolicy {

    public boolean dispatch(MessageReference node, MessageEvaluationContext msgContext, List<Subscription> consumers) throws Exception {
        //指定特定后缀名的topic进入自定义分发策略
        if(!node.getMessage().getDestination().getQualifiedName().endsWith(".ptp"))
            return super.dispatch(node, msgContext, consumers);

        String _clientId = "";
        //获取消息内容
        ByteSequence sequence = node.getMessage().getContent();
        byte[] message = sequence.getData();
        String strMessage = new String(message, "utf-8");

        //format：clientID@messageBody
        if (!"".equals(strMessage) && strMessage.indexOf("@")>-1) 
            _clientId = strMessage.substring(0, strMessage.indexOf("@"));
        if ("".equals(_clientId))
            return super.dispatch(node, msgContext, consumers);

        strMessage = strMessage.substring(strMessage.indexOf("@") + 1, strMessage.length());
        node.getMessage().setContent(new ByteSequence(strMessage.getBytes("utf-8")));

        ActiveMQDestination _destination = node.getMessage().getDestination();

        int count = 0;
        for (Subscription sub : consumers) {
            // Don't deliver to browsers
            if (sub.getConsumerInfo().isBrowser()) {
                continue;
            }
            // Only dispatch to interested subscriptions
            if (!sub.matches(node, msgContext)) {
                sub.unmatched(node);
                continue;
            }
            if (_clientId != null && _destination.isTopic() && _clientId.equals(sub.getContext().getClientId())
                    && _destination.getQualifiedName().endsWith(".ptp")) {
                //把消息推送给满足要求的subscription
                sub.add(node);
                count++;
            } else {
                sub.unmatched(node);
            }
        }

        return count > 0;
    }

}

下面展示的是第五步修改的内容，用文本编辑器打开mq程序根目录\conf\activemq.xml文件，寻找到broker标签，修改其中的内容

<destinationPolicy>
            <policyMap>
              <policyEntries>
                <policyEntry topic=">" >

                  <dispatchPolicy>
                    <!-- 这里的priorityDispatchPolicy是你选对的策略分发类，首字母小写 -->
                    <priorityDispatchPolicy />
                  </dispatchPolicy>

                  <pendingMessageLimitStrategy>
                    <constantPendingMessageLimitStrategy limit="1000"/>
                  </pendingMessageLimitStrategy>
                </policyEntry>
              </policyEntries>
            </policyMap>
        </destinationPolicy>

点对点测试程序

直接贴代码，不做解释啦

public class P2PMqttTest {
    public static Connection connection;
    public static Statement stat;

    public static void main(String[] args) throws JMSException {
        DefaultMessageListenerContainer container = new DefaultMessageListenerContainer();
        ActiveMQConnectionFactory factory = new ActiveMQConnectionFactory("admin", "admin", "tcp://localhost:61616");
        //consumer
        subMsg(factory, "mqtt-1011");
        subMsg(factory, "mqtt-1012");
        subMsg(factory, "aaaaaa");

        //product
        sendMsg(factory);
    }

    private static void subMsg(ActiveMQConnectionFactory factory, String clientId) throws JMSException {
        Connection connection = factory.createConnection();
        connection.setClientID(clientId);
        connection.start();
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        Topic topic = session.createTopic("channel.ptp");
        MessageConsumer consumer = session.createConsumer(topic);
        consumer.setMessageListener(new ConsumeListenerMessage(clientId));
    }

    private static void sendMsg(ActiveMQConnectionFactory factory) throws JMSException {
        Connection connection = factory.createConnection();
        connection.setClientID("mqtt-1022");
        connection.start();
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        Topic topic = session.createTopic("channel.ptp");
        MessageProducer producer = session.createProducer(topic);
        //clientId@messageBody
        Message message = session.createTextMessage("mqtt-1011"+"@"+"test");
        producer.send(message);
    }

    static class ConsumeListenerMessage implements MessageListener {
        private String thisClientId;

        public void onMessage(Message message) {
            TextMessage msg = (TextMessage) message;
            try {
                String clientId = msg.getStringProperty("PTP_CLIENTID");
                String msgBody = msg.getText();
                System.out.println("============================================");
                System.out.println(thisClientId+" recive message");
                System.out.println(msgBody);
                System.out.println("============================================");
            } catch (JMSException e) {
                e.printStackTrace();
            }
        }

        public ConsumeListenerMessage(String thisClientId) {
            this.thisClientId = thisClientId;
        }
    }
}

本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。