使用 ActiveMQ 示例

 

企業中各項目中相互協作的時候可能用得到消息通知機制。比如有東西更新了，可以通知做索引。

在 Java 裏有 JMS 的多個實現。其中 apache 下的 ActiveMQ 就是不錯的選擇。還有一個比較熱的是 RabbitMQ （是 erlang 語言實現的）。這裏示例下使用 ActiveMQ

用 ActiveMQ 最好還是瞭解下 JMS

JMS 公共	點對點域	發佈/訂閱域
ConnectionFactory	QueueConnectionFactory	TopicConnectionFactory
Connection	QueueConnection	TopicConnection
Destination	Queue	Topic
Session	QueueSession	TopicSession
MessageProducer	QueueSender	TopicPublisher
MessageConsumer	QueueReceiver	TopicSubscriber

JMS 定義了兩種方式：Quere（點對點）；Topic（發佈/訂閱）。

ConnectionFactory 是連接工廠，負責創建Connection。

Connection 負責創建 Session。

Session 創建 MessageProducer（用來發消息） 和 MessageConsumer（用來接收消息）。

Destination 是消息的目的地。

詳細的可以網上找些 JMS 規範（有中文版）。

下載 apache-activemq-5.3.0。http://activemq.apache.org/download.html，解壓，然後雙擊 bin/activemq.bat。運行後，可以在 http://localhost:8161/admin 觀察。也有 demo， http://localhost:8161/demo。把 activemq-all-5.3.0.jar 加入 classpath。

Jms 發送 代碼：

public static void main(String[] args) throws Exception {
    ConnectionFactory connectionFactory = new ActiveMQConnectionFactory();

    Connection connection = connectionFactory.createConnection();
    connection.start();

    Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
    Destination destination = session.createQueue("my-queue");

    MessageProducer producer = session.createProducer(destination);
    for(int i=0; i<3; i++) {
        MapMessage message = session.createMapMessage();
        message.setLong("count", new Date().getTime());
        Thread.sleep(1000);
        //通過消息生產者發出消息
        producer.send(message);
    }
    session.commit();
    session.close();
    connection.close();
}

public static void main(String[] args) throws Exception {
	ConnectionFactory connectionFactory = new ActiveMQConnectionFactory();

	Connection connection = connectionFactory.createConnection();
	connection.start();

	Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
	Destination destination = session.createQueue("my-queue");

	MessageProducer producer = session.createProducer(destination);
	for(int i=0; i<3; i++) {
		MapMessage message = session.createMapMessage();
		message.setLong("count", new Date().getTime());
		Thread.sleep(1000);
		//通過消息生產者發出消息
		producer.send(message);
	}
	session.commit();
	session.close();
	connection.close();
}

Jms 接收代碼：

public static void main(String[] args) throws Exception {
    ConnectionFactory connectionFactory = new ActiveMQConnectionFactory();

    Connection connection = connectionFactory.createConnection();
    connection.start();

    final Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
    Destination destination = session.createQueue("my-queue");

    MessageConsumer consumer = session.createConsumer(destination);
    /*//listener 方式
    consumer.setMessageListener(new MessageListener() {

        public void onMessage(Message msg) {
            MapMessage message = (MapMessage) msg;
            //TODO something....
            System.out.println("收到消息：" + new Date(message.getLong("count")));
            session.commit();
        }

    });
    Thread.sleep(30000);
    */
    int i=0;
    while(i<3) {
        i++;
        MapMessage message = (MapMessage) consumer.receive();
        session.commit();

        //TODO something....
        System.out.println("收到消息：" + new Date(message.getLong("count")));
    }

    session.close();
    connection.close();
}

public static void main(String[] args) throws Exception {
	ConnectionFactory connectionFactory = new ActiveMQConnectionFactory();

	Connection connection = connectionFactory.createConnection();
	connection.start();

	final Session session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE);
	Destination destination = session.createQueue("my-queue");

	MessageConsumer consumer = session.createConsumer(destination);
	/*//listener 方式
	consumer.setMessageListener(new MessageListener() {

		public void onMessage(Message msg) {
			MapMessage message = (MapMessage) msg;
			//TODO something....
			System.out.println("收到消息：" + new Date(message.getLong("count")));
			session.commit();
		}

	});
	Thread.sleep(30000);
	*/
	int i=0;
	while(i<3) {
		i++;
		MapMessage message = (MapMessage) consumer.receive();
		session.commit();

		//TODO something....
		System.out.println("收到消息：" + new Date(message.getLong("count")));
	}

	session.close();
	connection.close();
}

啓動 JmsReceiver 和 JmsSender 可以在看輸出三條時間信息。當然 Jms 還指定有其它格式的數據，如 TextMessage

結合 Spring 的 JmsTemplate 方便用：

xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

<!-- 在非 web / ejb 容器中使用 pool 時，要手動 stop，spring 不會爲你執行 destroy-method 的方法
    <bean id="jmsFactory" class="org.apache.activemq.pool.PooledConnectionFactory" destroy-method="stop">
        <property name="connectionFactory">
            <bean class="org.apache.activemq.ActiveMQConnectionFactory">
                <property name="brokerURL" value="tcp://localhost:61616" />
            </bean>
        </property>
    </bean>
-->
    <bean id="jmsFactory" class="org.apache.activemq.ActiveMQConnectionFactory">
        <property name="brokerURL" value="tcp://localhost:61616" />
    </bean>
    <bean id="jmsTemplate" class="org.springframework.jms.core.JmsTemplate">
        <property name="connectionFactory" ref="jmsFactory" />
        <property name="defaultDestination" ref="destination" />
        <property name="messageConverter">
            <bean class="org.springframework.jms.support.converter.SimpleMessageConverter" />
        </property>
    </bean>

    <bean id="destination" class="org.apache.activemq.command.ActiveMQQueue">
        <constructor-arg index="0" value="my-queue" />
    </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
		xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

<!-- 在非 web / ejb 容器中使用 pool 時，要手動 stop，spring 不會爲你執行 destroy-method 的方法
	<bean id="jmsFactory" class="org.apache.activemq.pool.PooledConnectionFactory" destroy-method="stop">
		<property name="connectionFactory">
			<bean class="org.apache.activemq.ActiveMQConnectionFactory">
				<property name="brokerURL" value="tcp://localhost:61616" />
			</bean>
		</property>
	</bean>
-->
	<bean id="jmsFactory" class="org.apache.activemq.ActiveMQConnectionFactory">
		<property name="brokerURL" value="tcp://localhost:61616" />
	</bean>
	<bean id="jmsTemplate" class="org.springframework.jms.core.JmsTemplate">
		<property name="connectionFactory" ref="jmsFactory" />
		<property name="defaultDestination" ref="destination" />
		<property name="messageConverter">
			<bean class="org.springframework.jms.support.converter.SimpleMessageConverter" />
		</property>
	</bean>

	<bean id="destination" class="org.apache.activemq.command.ActiveMQQueue">
		<constructor-arg index="0" value="my-queue" />
	</bean>

</beans>

sender：

public static void main(String[] args) {
    ApplicationContext ctx = new FileSystemXmlApplicationContext("classpath:app*.xml");

    JmsTemplate jmsTemplate = (JmsTemplate) ctx.getBean("jmsTemplate");

    jmsTemplate.send(new MessageCreator() {

        public Message createMessage(Session session) throws JMSException {
            MapMessage mm = session.createMapMessage();
            mm.setLong("count", new Date().getTime());
            return mm;
        }

    });
}

public static void main(String[] args) {
	ApplicationContext ctx = new FileSystemXmlApplicationContext("classpath:app*.xml");

	JmsTemplate jmsTemplate = (JmsTemplate) ctx.getBean("jmsTemplate");

	jmsTemplate.send(new MessageCreator() {

		public Message createMessage(Session session) throws JMSException {
			MapMessage mm = session.createMapMessage();
			mm.setLong("count", new Date().getTime());
			return mm;
		}

	});
}

receiver：

public static void main(String[] args) {
    ApplicationContext ctx = new FileSystemXmlApplicationContext("classpath:app*.xml");

    JmsTemplate jmsTemplate = (JmsTemplate) ctx.getBean("jmsTemplate");
    while(true) {
        Map<String, Object> mm =  (Map<String, Object>) jmsTemplate.receiveAndConvert();
        System.out.println("收到消息：" + new Date((Long)mm.get("count")));
    }
}

public static void main(String[] args) {
	ApplicationContext ctx = new FileSystemXmlApplicationContext("classpath:app*.xml");

	JmsTemplate jmsTemplate = (JmsTemplate) ctx.getBean("jmsTemplate");
	while(true) {
		Map<String, Object> mm =  (Map<String, Object>) jmsTemplate.receiveAndConvert();
		System.out.println("收到消息：" + new Date((Long)mm.get("count")));
	}
}

注意：直接用 Jms 接口時接收了消息後要提交一下，否則下次啓動接收者時還可以收到舊數據。有了 JmsTemplate 就不用自己提交 session.commit() 了。如果使用了 PooledConnectionFactory 要把 apache-activemq-5.3.0\lib\optional\activemq-pool-5.3.0.jar 加到 classpath

參考資料：

Hello ActiveMQ

Spring2.5整合ActiveMQ 5.2

spring-support

JMS 相關資料

 

轉載自：http://blog.chenlb.com/2010/01/activemq-hello.html