Spring JMS和ActiveMQ的应用
笔者近期参与一个分析log的项目。主要流程是：读取Log文件，对每一行Text解析成对应的Object，解析器会将多个Object存放到一个List中并发送到ActiveMQ的Queue中，即Queue中的一个Message即应一个Objects List。然后数据处理thread会consume存放在Queue中的Message，并将处理的结果保存到db。
采用JMS来实现读取Log和分析Log之间的异步运行，使用ActiveMQ的可持久化的Queue，当Message被放进Queue中并持久化后，就会更新Log的读取进度，这样即使程序break down，也不会导致数据被漏掉。
使用Spring来配置JMS，则可以简化和方便JMS的使用，同时还可以使用到Transaction Management。
由于程序并不是很复杂，同时也不需要单独提供ActiveMQ server来运行，所以这里使用的是embed的方式。
总的来说，程序运行起来之后，将会启动以下几个Service：
1. JMS service，这个service会启动一个embed broker。
2. Data Reader & Parser service，这个service会引用一个JMS Message Provider，用于发送Message到Queue中。
3. 使用Message Listener Containers来监听Queue，并使用MDP(Message Drive POJO)的方法，来处理并消费掉Message。
本文主要说明如何通过Spring的配置来实现JMS和ActiveMQ的应用，对于这个程序的其他的代码不涉及。
第一步，JMS Service并start embed broker
public class JMSService extends AbstractService {
private BrokerService broker;
private String mqConfigFile = "xbean:activemq.xml";
public void start() throws Exception {
if(broker == null) {
broker = BrokerFactory.createBroker(new URI(mqConfigFile));
broker.start();
broker.waitUntilStarted();
}
super.start();
}
public void stop() throws Exception {
if(broker != null && broker.isStarted()) {
broker.stop();
broker.waitUntilStopped();
}
super.stop();
}
}
这里使用BrokerService broker = BrokerFactory.createBroker(new URI(someURI));来创建一个broker，关于someURI的配置，详见这里：http://activemq.apache.org/broker-configuration-uri.html
我这里的xbean:activemq.xml如下：
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<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:amq="http://activemq.apache.org/schema/core" 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-2.0.xsd
http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
<!-- Allows us to use system properties as variables in this configuration
file -->
<bean
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>mw.properties</value>
</property>
</bean>
<!-- The <broker> element is used to configure the ActiveMQ broker. -->
<broker useJmx="true" xmlns="http://activemq.apache.org/schema/core"
brokerName="${activemq.broker.name}" dataDirectory="${activemq.broker.datadir}">
<destinationPolicy>
<policyMap>
<policyEntries>
<policyEntry topic=">" producerFlowControl="true"
memoryLimit="10mb">
<pendingSubscriberPolicy>
<vmCursor />
</pendingSubscriberPolicy>
</policyEntry>
<policyEntry queue="mdp.queue." producerFlowControl="true"
memoryLimit="128mb">
</policyEntry>
</policyEntries>
</policyMap>
</destinationPolicy>
<!-- The managementContext is used to configure how ActiveMQ is exposed
in JMX. By default, ActiveMQ uses the MBean server that is started by the
JVM. For more information, see: http://activemq.apache.org/jmx.html -->
<managementContext>
<managementContext createConnector="true" />
</managementContext>
<!-- Configure message persistence for the broker. The default persistence
mechanism is the KahaDB store (identified by the kahaDB tag). For more information,
see: http://activemq.apache.org/persistence.html -->
<persistenceAdapter>
<kahaDB directory="${activemq.broker.datadir}/kahadb"
journalMaxFileLength="96mb" indexWriteBatchSize="10000"
indexCacheSize="100000" />
</persistenceAdapter>
<plugins>
<!-- Configure authentication; Username, passwords and groups -->
<simpleAuthenticationPlugin>
<users>
<authenticationUser username="${activemq.userName}"
password="${activemq.password}" groups="users,admins" />
<authenticationUser username="admin" password="pass"
groups="users" />
<authenticationUser username="guest" password="pass"
groups="guests" />
</users>
</simpleAuthenticationPlugin>
<!-- Lets configure a destination based authorization mechanism -->
<authorizationPlugin>
<map>
<authorizationMap>
<authorizationEntries>
<authorizationEntry queue=">" read="admins"
write="admins" admin="admins" />
<authorizationEntry queue="USERS.>" read="users"
write="users" admin="users" />
<authorizationEntry queue="GUEST.>" read="guests"
write="guests,users" admin="guests,users" />
<authorizationEntry queue="TEST.Q" read="guests"
write="guests" />
<authorizationEntry topic=">" read="admins"
write="admins" admin="admins" />
<authorizationEntry topic="USERS.>" read="users"
write="users" admin="users" />
<authorizationEntry topic="GUEST.>" read="guests"
write="guests,users" admin="guests,users" />
<authorizationEntry topic="ActiveMQ.Advisory.>"
read="guests,users" write="guests,users" admin="guests,users" />
</authorizationEntries>
</authorizationMap>
</map>
</authorizationPlugin>
</plugins>
<!-- The systemUsage controls the maximum amount of space the broker will
use before slowing down producers. For more information, see: http://activemq.apache.org/producer-flow-control.html -->
<systemUsage>
<systemUsage>
<memoryUsage>
<memoryUsage limit="2048 mb" />
</memoryUsage>
<storeUsage>
<storeUsage limit="32 gb" name="mdp" />
</storeUsage>
<tempUsage>
<tempUsage limit="1024 mb" />
</tempUsage>
</systemUsage>
</systemUsage>
<!-- The transport connectors expose ActiveMQ over a given protocol to
clients and other brokers. For more information, see: http://activemq.apache.org/configuring-transports.html -->
<transportConnectors>
<transportConnector name="openwire" uri="${activemq.broker.url}" />
</transportConnectors>
</broker>
<!-- Uncomment to enable Camel Take a look at activemq-camel.xml for more
details <import resource="camel.xml"/> -->
<!-- Enable web consoles, REST and Ajax APIs and demos Take a look at activemq-jetty.xml
for more details <import resource="jetty.xml"/> -->
</beans>
第二步，配置JMS ConnectionFactory和Destination
<bean id="jmsConnectionFactory" class="org.apache.activemq.ActiveMQConnectionFactory"> <property name="brokerURL"> <value>vm://localhost:61616</value> </property> </bean> <!-- Queue --> <bean id="destinationQueue" class="org.apache.activemq.command.ActiveMQQueue"> <constructor-arg index="0"> <value>UserMessageQueue</value> </constructor-arg> </bean>
第三步，配置JMS Template，以及Message converter
<!-- Spring JmsTemplate config --> <bean id="jmsTemplate" class="org.springframework.jms.core.JmsTemplate"> <property name="connectionFactory"> <!-- lets wrap in a pool to avoid creating a connection per send --> <bean class="org.springframework.jms.connection.SingleConnectionFactory"> <property name="targetConnectionFactory" ref="jmsConnectionFactory" /> </bean> </property> <!-- custom MessageConverter --> <!-- no message converter configured, so it'll use the SimpleMessageConverter --> </bean>
注意，这里使用了一个 SingleConnectionFactory，这是spring对ConnectionFactory的一个实现，这个实现会在调用createConnection的地方返回相同的Connection并且忽略所有的close()方法，这样多个JMSTemplate可以共用一个相同的connection，避免每次都重复创建connection造成资源的浪费。
并且，我没有配置MessageConverter，而且使用Spring自带的SimpleMessageConverter，这是默认选项，不配就是使用SimpleMessageConverter。
第四步，配置JMS Message producer
<!-- POJO which send Message uses Spring JmsTemplate --> <bean id="userMessageProducer" class="cn.lettoo.meetingwatch.jms.UserMessageProducer"> <property name="template" ref="jmsTemplate" /> <property name="destination" ref="destinationQueue" /> </bean>
Message Producer通过JMS Template和destination来发送Message。下面是代码实现：
public class UserMessageProducer implements IMessageProducer {
protected JmsTemplate template;
protected Queue destination;
public void setTemplate(JmsTemplate template) {
this.template = template;
}
public void setDestination(Queue destination) {
this.destination = destination;
}
public void send(Object object) {
template.convertAndSend(this.destination, object);
}
}
因为我并没有为JMS template指定特定的MessageConverter，所以这里template.convertAndSend()应该就是SimpleMessageConverter.convertAndSend()来实现的。
第五步，配置JMS Message Consumer
我并没有在spring的配置文件单独配置一个Message Consumer，这是一个非常简单的POJO，这里只是为测试写的一个简单示例：只是简单把读到的Message打印出来。
public class UserMessageConsumer {
public void printUser(User user) {
user.getId();
user.getName();
System.out.println(user);
}
}
第六步，配置JMS Message Listener Container以及Listerer
<!-- Message Driven POJO --> <bean id="messageListener" class="org.springframework.jms.listener.adapter.MessageListenerAdapter"> <constructor-arg> <bean class="cn.lettoo.meetingwatch.jms.UserMessageConsumer"> </bean> </constructor-arg> <property name="defaultListenerMethod" value="printUser" /> </bean> <!-- listener container --> <bean id="listenerContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer"> <property name="connectionFactory" ref="jmsConnectionFactory" /> <property name="destination" ref="destinationQueue" /> <property name="messageListener" ref="messageListener" /> </bean>
这里使用org.springframework.jms.listener.adapter.MessageListenerAdapter来实现一个Listener，这样做的好处是，可以使用非常简单的POJO来作为一个consumer，就是上面的UserMessageConsumer一样。当Queue里有一条Message的时候，会使用UserMessageConsumer的printUser来消费掉这条Message。
Spring JMS提供3种ListenerContainer，最常使用的是DefaultMessageListenerContainer。这里把Listener注入，来实现对Message的Listener。
参考：