使用 ActiveMQ 示例

原文出处：http://blog.chenlb.com/2010/01/activemq-hello.html

企业中各项目中相互协作的时候可能用得到消息通知机制。比如有东西更新了，可以通知做索引。

在 Java 里有 JMS 的多个实现。其中 apache 下的 ActiveMQ 就是不错的选择。还有一个比较热的是 RabbitMQ （是 erlang 语言实现的）。这里示例下使用 ActiveMQ

用 ActiveMQ 最好还是了解下 JMS

JMS 公共	点对点域	发布/订阅域
ConnectionFactory	QueueConnectionFactory	TopicConnectionFactory
Connection	QueueConnection	TopicConnection
Destination	Queue	Topic
Session	QueueSession	TopicSession
MessageProducer	QueueSender	TopicPublisher
MessageConsumer	QueueReceiver	TopicSubscriber

JMS 定义了两种方式：Quere（点对点）；Topic（发布/订阅）。

ConnectionFactory 是连接工厂，负责创建Connection。

Connection 负责创建 Session。

Session 创建 MessageProducer（用来发消息） 和 MessageConsumer（用来接收消息）。

Destination 是消息的目的地。

详细的可以网上找些 JMS 规范（有中文版）。

下载 apache-activemq-5.3.0。http://activemq.apache.org/download.html ，解压，然后双击 bin/activemq.bat。运行后，可以在 http://localhost:8161/admin 观察。也有 demo， http://localhost:8161/demo 。把 activemq-all-5.3.0.jar 加入 classpath。

Jms 发送 代码：

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
);
        //通过消息生产者发出消息
        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);
		//通过消息生产者发出消息
		producer.send(message);
	}
	session.commit();
	session.close();
	connection.close();
}

Jms 接收代码：

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();
}

启动 JmsReceiver 和 JmsSender 可以在看输出三条时间信息。当然 Jms 还指定有其它格式的数据，如 TextMessage

结合 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 时，要手动 stop，spring 不会为你执行 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 时，要手动 stop，spring 不会为你执行 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 接口时接收了消息后要提交一下，否则下次启动接收者时还可以收到旧数据。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

参考资料：

Hello ActiveMQ

Spring2.5整合ActiveMQ 5.2

spring-support

JMS 相关资料