第十一章ActiveMQ代理器的新特性【笔记】

概述：主要介绍代理器比较炫特效，好用的功能。

11.1、介绍

包括通配符、多个目的地，提示信息、虚拟话题（topic）， 过期消息队列

11.2、通配符和多个目的地

11.2.1、订阅使用通配符目的地

有三种特殊通配符

.   : 点 用于区分目的地名称的元素

* ： 星号，匹配一个元素（这个和一般通配符不一样）

> : 右尖括号，配置一个或多个元素

String brokerURI = ActiveMQConnectionFactory.DEFAULT_BROKER_URL;ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(brokerURI);Connection connection = connectionFactory.createConnection();connection.start();Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);Topic allLeeds = session.createTopic("*.*.Leeds");MessageConsumer consumer = session.createConsumer(allLeeds);Message result = consumer.receive();

11.2.2.将消息发送到多个目的地

以逗号隔开   例如：session.createQueue("store.orders, topic://store.orders");

String brokerURI = ActiveMQConnectionFactory.DEFAULT_BROKER_URL;ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(brokerURI);Connection connection = connectionFactory.createConnection();connection.start();Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);Queue ordersDestination = session.createQueue("store.orders, topic://store.orders");MessageProducer producer = session.createProducer(ordersDestination);Message order = session.createObjectMessage();producer.send(order);

11.3、提示信息

系统提示信息，生成提示信息会产生Advisory相关属性

originBrokerId : 生成Id

originBrokerName: 名称

originBrokerURL : 传输url地址

String brokerURI = ActiveMQConnectionFactory.DEFAULT_BROKER_URL;ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(brokerURI);Connection connection = connectionFactory.createConnection();connection.start();Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);Topic connectionAdvisory = org.apache.activemq.advisory.AdvisorySupport.CONNECTION_ADVISORY_MessageConsumer consumer = session.createConsumer(connectionAdvisory);ActiveMQMessage message = (ActiveMQMessage) consumer.receive();DataStructure data = (DataStructure) message.getDataStructure();if (data.getDataStructureType() == ConnectionInfo.DATA_STRUCTURE_TYPE) {ConnectionInfo connectionInfo = (ConnectionInfo) data;System.out.println("Connection started: " + connectionInfo);} else if (data.getDataStructureType() == RemoveInfo.DATA_STRUCTURE_TYPE) {RemoveInfo removeInfo = (RemoveInfo) data;System.out.println("Connection stopped: " + removeInfo.getObjectId());} else {System.err.println("Unknown message " + data);}

<destinationPolicy>    <policyMap>        <policyEntries>            <policyEntry queue=">" advisoryForSlowConsumers="true" />        </policyEntries>    </policyMap></destinationPolicy>

11.4、虚拟话题

将多个queue组成一个topic（只是虚拟，实际不存在）

String brokerURI = ActiveMQConnectionFactory.DEFAULT_BROKER_URL;ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(brokerURI);Connection consumerConnection = connectionFactory.createConnection();consumerConnection.start();    Session consumerSessionA = consumerConnection.createSession(false,Session.AUTO_ACKNOWLEDGE);Queue consumerAQueue = consumerSessionA.createQueue("Consumer.A.VirtualTopic.orders");MessageConsumer consumerA = consumerSessionA.createConsumer(consumerAQueue);Session consumerSessionB = consumerConnection.createSession(false,Session.AUTO_ACKNOWLEDGE);Queue consumerBQueue = consumerSessionB.createQueue("Consumer.B.VirtualTopic.orders");MessageConsumer consumerB = consumerSessionB.createConsumer(consumerAQueue);//setup the senderConnection senderConnection = connectionFactory.createConnection();senderConnection.start();Session senerSession = senderConnection.createSession(false, Session.AUTO_ACKNOWLEDGE);Topic ordersDestination = senerSession.createTopic("VirtualTopic.orders");MessageProducer producer = senerSession.createProducer(ordersDestination);         

11.5、重新连接消费者

可以在断开连接之后，保存发送的消息，连接上在发送

设置consumer.retroactive=true

String brokerURI = ActiveMQConnectionFactory.DEFAULT_BROKER_URL;ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(brokerURI);Connection connection = connectionFactory.createConnection();connection.start();Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);Topic topic = session.createTopic("soccer.division1.leeds?consumer.retroactive=true");MessageConsumer consumer = session.createConsumer(topic);Message result = consumer.receive();

在服务端需要配置

<destinationPolicy>    <policyMap>        <policyEntries>            <policyEntry topic=">">                <subscriptionRecoveryPolicy>                    <fixedSizedSubscriptionRecoveryPolicy />                </subscriptionRecoveryPolicy>            </policyEntry>        </policyEntries>    </policyMap></destinationPolicy>

11.6、消息再次传递和失效消息队列

对于那些过期消息会移动到Dead Letter Queue(失效消息队列)，随后可以由管理员查看

消息会重新传递的情况：

• 客户端使用事务时调用rollback()方法
• 客户端使用事务，在提交之前关闭。
• 客户端正在使用CLIENT_ACKNOWLEDGE，然后调用recover

配置恢复规则

RedeliveryPolicy policy = connection.getRedeliveryPolicy();policy.setInitialRedeliveryDelay(500);policy.setBackOffMultiplier(2);policy.setUseExponentialBackOff(true);policy.setMaximumRedeliveries(2);

配置失效消息队列

<destinationPolicy>    <policyMap>        <policyEntries>            <policyEntry queue=">">                <deadLetterStrategy>                    <individualDeadLetterStrategy queuePrefix="DLQ." useQueueForQueueMessages="true" processExpired="false" processNonPersistent="false" />                </deadLetterStrategy>            </policyEntry>        </policyEntries>    </policyMap></destinationPolicy>

注意：这个配置忽略非持久和过期消息