ACTIVEMQ相关知识点

JMS始终在JavaEE五花八门的协议里，WebService满天飞的时候占一位置，是因为：

   它可以把不影响用户执行结果又比较耗时的任务（比如发邮件通知管理员）异步的扔给JMS 服务端去做，而尽快的把屏幕返还给用户。服务端能够多线程排队响应高并发的请求。可以在Java世界里达到最高的解耦。客户端与服务端无需直连，甚至无需知晓对方是谁、在哪里、有多少人，只要对流过的信息作响应就行了，在企业应用环境复杂时作用明显。

 

JMS(Java Message Service)即 java消息服务 用于分布式系统得消息通信，JMS是J2EE技术中的一个部分，Sun公司定义了JMS的标准接口，即javax.jms.*。JMS服务使得分布式系统的信息通信松散连接的，发送信息的客户端只需要负责发送信息，接收信息的客户端接收信息，两个客户端之间没有必要是同时可用的，甚至发送客户端都没有必要知道客户端的信息，只要负责发送到接收的服务端就可以，JMS可以说是低耦合的。同时JMS API 做到了以下2点：
异步的，服务端可以发送信息到一个客户端，客户端不需要为了收到信息而请求信息。

可靠的，JMS API保证了服务端所有发送的信息最少发送一次和只发送一次，下面介绍一些JMS API 的基本知识

JMS API 基本组成

        JMS provider服务者，是一个消息系统通过实现JMS API 接口，用于管理和控制信息。l
     l   JMS client   客户端  用于发送和接收信息，通常是用在java程序中用java编写的
        Messagesl 用于在客户端信息通信的对象
        Administered Objects 由JMSl provider为了client创建的对象，通常是connectionFactory和destination

Messages 通信方式
JMS通信方式分为点对点通信，和发布/订阅方式

点对点方式（point-to-point）
点对点的消息发送方式主要建立在 Message Queue,Sender,reciever上，Message Queue 存贮消息，Sneder 发送消息，receive接收消息，具体的信息就是 Sender Client发送Message 到Queue ,而 receiver Cliernt 从Queue中接收消息和发送消息已接受到Quere,确认消息接收。在使用点对点方式时需要注意，一条消息只有一个接收端，消息发送客户端与接收客户端没有时间上的依赖，发送客户端可以在任何时刻发送信息到Queue，而不需要知道接收客户端是不是在运行

发布/订阅 方式（publish/subscriber Messaging）
发布/订阅方式用于多接收客户端的方式
作为发布订阅的方式，可能存在多个接收客户端，并且接收端客户端与发送客户端存在时间上的依赖。一个接收端只能接收他创建以后发送客户端发送的信息。

作为subscriber ,在接收消息时有两种方法，destination的receive方法，和实现message listener 接口的onMessage 方法。

基础知识这里说的很少，具体的可以参照java.sun.com.的JMS API 指南

ActiveMQ的特性：

完全支持JMS1.1和J2EE 1.4规范的 JMS Provider实现，也是Apache Geronimo默认的JMS provider。

POJO withdout EJB Container，不需要实现EJB繁琐复杂的Message Bean接口和配置。

Spring Base，可以使用Spring的各种特性如IOC、AOP 。

Effective，基于Jencks的JCA Container实现 pool connection，control transactions and manage security。 

下面是它的特性列表 
    1.多种语言和协议编写客户端
     语言: Java, C, C++, C#, Ruby, Perl, Python, PHP 
     应用协议: OpenWire,Stomp REST,WS Notification,XMPP,AMQP
    2.完全支持JMS1.1和J2EE 1.4规范  (持久化,XA消息,事务)
    3.对Spring的支持,ActiveMQ可以很容得内嵌到使用Spring的系统里面去,而且也支持Spring2.0的特性
   4.通过了常见J2EE服务器(如 Geronimo,JBoss 4, GlassFish,WebLogic)的测试,其中通过JCA 1.5 resource adaptors的配置,
    可以让ActiveMQ可以自动的部署到任何兼容J2EE 1.4 商业服务器上
    5.支持多种传送协议:in-VM,TCP,SSL,NIO,UDP,JGroups,JXTA
    6.支持通过JDBC和journal提供高速的消息持久化
    7.从设计上保证了高性能的集群,客户端-服务器,点对点
    8.支持Ajax
    9.支持与Axis的整合
    10.可以很容易得调用内嵌JMS provider,进行测试

 

作为一个JMS client 都需要以下的组成
Administered Objects：ConnectionFactory，Destination
Connection；
Session
Message Producers/Message Cosumers
Messages

 

Hello实例

=================================Hello.java===========================

import java.io.Serializable;

/**Hello.java用来传递JAVA对象
* Author: cjp
* Date: 2005-11-8
* Time: 22:24:02
*/
public class Hello implements Serializable {
private String id;
private Hello hello;
private PointList pointList;
public String getId() {
return id;
}

public void setId(String id) {
this.id = id;
}

public Hello getHello() {
return hello;
}

public void setHello(Hello hello) {
this.hello = hello;
}
}

=========================SpringTest .java========================

import org.springframework.jms.core.JmsTemplate;
import org.springframework.jms.core.MessageCreator;
import org.springframework.test.AbstractDependencyInjectionSpringContextTests;

import javax.jms.*;

/**

*发送JMS消息

*/
public class SpringTest extends AbstractDependencyInjectionSpringContextTests
{
protected String[] getConfigLocations()
{
return new String[]{"file:D:\\wosame\\test\\com\\wosame\\room\\jms\\jms.xml"};
}

public void testSendMessage() throws Exception
{
JmsTemplate jmsTemplate = (JmsTemplate) applicationContext.getBean("jmsTemplate");
jmsTemplate.send(new MessageCreator()
{
public Message createMessage(Session session) throws JMSException
{
ObjectMessage message=session.createObjectMessage();
Hello hello=new Hello();
hello.setId("test");
message.setObject(hello);
return message;
}
});
}
}

================================HelloMDP .java==================================

/**

处理JMS消息

*/

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import javax.jms.*;

public class HelloMDP implements MessageListener
{
protected Log log = LogFactory.getLog(HelloMDP.class);

public void onMessage(Message message)
{
try
{
ObjectMessage objMessage = (ObjectMessage) message;
Hello hello= (Hello) objMessage.getObject();
System.out.println("hello.getId() = " + hello.getId());
} catch (JMSException e)
{
log.error("Parse failed", e);
}
}
}

================================jms.xml==================================

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
" http://www.springframework.org/dtd/spring-beans.dtd">

<beans>

<!--嵌入式的JMS连接，也就是跟随JVM一起启动,可以参看activemq的文档-->
<bean id="connectionFactory" class="org.activemq.ActiveMQConnectionFactory"> <property name="brokerURL" value="vm://localhost"/>
<property name="useEmbeddedBroker" value="true"/>
</bean>

<!--消息监听器，也就是消息的具体的处理器-->
<bean id="HelloMDP" class="HelloMDP"/>

<!--jms监听需要JTA容器的支持-->
<bean id="activeMQContainer" class="org.activemq.jca.JCAContainer">
<property name="workManager">
<bean id="workManager" class="org.activemq.work.SpringWorkManager"/>
</property>
<property name="resourceAdapter">
<bean id="activeMQResourceAdapter" class="org.activemq.ra.ActiveMQResourceAdapter">
<property name="serverUrl" value="vm://localhost"/>
</bean>
</property>
</bean>

<!--消息的消费者，也就是将监听器与具体的队列关联-->
<bean id="HelloQueueConsumer" factory-method="addConnector" factory-bean="activeMQContainer">
<property name="activationSpec">
<bean class="org.activemq.ra.ActiveMQActivationSpec">
<property name="destination" value="Hello.Queue"/>
<property name="destinationType" value="javax.jms.Queue"/>
</bean>
</property>
<property name="ref" value="HelloMDP"/>
</bean>

<!--spring的JMS template,用来发送JMS消息到指定的队列-->
<bean id="jmsTemplate" class="org.springframework.jms.core.JmsTemplate">
<property name="defaultDestinationName" value="Hello.Queue"/>
<property name="connectionFactory" ref="connectionFactory"/>
</bean>
</beans>

 

例子二 MQ源码

import java.util.Arrays;
import java.util.Date;

import javax.jms.Connection;
import javax.jms.DeliveryMode;
import javax.jms.Destination;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.util.IndentPrinter;

/**
* A simple tool for publishing messages
* 
* @version $Revision: 1.2 $
*/
public class ProducerTool {

        private Destination destination;
        private int messageCount = 10;
        private long sleepTime = 0L;
        private boolean verbose = true;
        private int messageSize = 255;
        private long timeToLive;
        private String user = ActiveMQConnection.DEFAULT_USER;
        private String password = ActiveMQConnection.DEFAULT_PASSWORD;
        private String url = ActiveMQConnection.DEFAULT_BROKER_URL;
        private String subject = "TOOL.DEFAULT";
        private boolean topic = false;
        private boolean transacted = false;
        private boolean persistent = false;

        public static void main(String[] args) {
                ProducerTool producerTool = new ProducerTool();
            String[] unknonwn = CommnadLineSupport.setOptions(producerTool, args);
            if( unknonwn.length > 0 ) {
                    System.out.println("Unknown options: "+Arrays.toString(unknonwn));
                        System.exit(-1);
            }                    
            producerTool.run();
        }

        public void run() {
                Connection connection=null;
                try {
                        System.out.println("Connecting to URL: " + url);
                        System.out.println("Publishing a Message with size " + messageSize+ " to " + (topic ? "topic" : "queue" + ": " + subject);
                        System.out.println("Using " + (persistent ? "persistent" : "non-persistent" + " messages" ;
                        System.out.println("Sleeping between publish " + sleepTime + " ms" ;
                        if (timeToLive != 0) {
                                System.out.println("Messages time to live " + timeToLive + " ms" ;
                        }
                        
                        // Create the connection.
                        ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(user, password, url);                        
                        connection = connectionFactory.createConnection();
                        connection.start();
                        
                        // Create the session
                        Session session = connection.createSession(transacted, Session.AUTO_ACKNOWLEDGE);
                        if (topic) {
                                destination = session.createTopic(subject);
                        } else {
                                destination = session.createQueue(subject);
                        }
                        
                        // Create the producer.
                        MessageProducer producer = session.createProducer(destination);
                        if (persistent) {
                                producer.setDeliveryMode(DeliveryMode.PERSISTENT);
                        } else {
                                producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
                        }                        
                        if (timeToLive != 0)
                                producer.setTimeToLive(timeToLive);
                                                
                        // Start sending messages
                        sendLoop(session, producer);

                        System.out.println("Done." ;
                        
                        // Use the ActiveMQConnection interface to dump the connection stats.
                        ActiveMQConnection c = (ActiveMQConnection) connection;
                        c.getConnectionStats().dump(new IndentPrinter());
                                                
                } catch (Exception e) {
                        System.out.println("Caught: " + e);
                        e.printStackTrace();
                } finally {
                        try { 
                                connection.close();
                        } catch (Throwable ignore) {
                        }
                }
        }

        protected void sendLoop(Session session, MessageProducer producer)
                        throws Exception {

                for (int i = 0; i < messageCount || messageCount == 0; i++) {

                        TextMessage message = session
                                        .createTextMessage(createMessageText(i));

                        if (verbose) {
                                String msg = message.getText();
                                if (msg.length() > 50) {
                                        msg = msg.substring(0, 50) + "...";
                                }
                                System.out.println("Sending message: " + msg);
                        }

                        producer.send(message);
                        if (transacted) {
                                session.commit();
                        }

                        Thread.sleep(sleepTime);

                }

        }

        private String createMessageText(int index) {
                StringBuffer buffer = new StringBuffer(messageSize);
                buffer.append("Message: " + index + " sent at: " + new Date());
                if (buffer.length() > messageSize) {
                        return buffer.substring(0, messageSize);
                }
                for (int i = buffer.length(); i < messageSize; i++) {
                        buffer.append(' ');
                }
                return buffer.toString();
        }

        public void setPersistent(boolean durable) {
                this.persistent = durable;
        }
        public void setMessageCount(int messageCount) {
                this.messageCount = messageCount;
        }
        public void setMessageSize(int messageSize) {
                this.messageSize = messageSize;
        }
        public void setPassword(String pwd) {
                this.password = pwd;
        }
        public void setSleepTime(long sleepTime) {
                this.sleepTime = sleepTime;
        }
        public void setSubject(String subject) {
                this.subject = subject;
        }
        public void setTimeToLive(long timeToLive) {
                this.timeToLive = timeToLive;
        }
        public void setTopic(boolean topic) {
                this.topic = topic;
        }
        public void setQueue(boolean queue) {
                this.topic = !queue;
        }        
        public void setTransacted(boolean transacted) {
                this.transacted = transacted;
        }
        public void setUrl(String url) {
                this.url = url;
        }
        public void setUser(String user) {
                this.user = user;
        }
        public void setVerbose(boolean verbose) {
                this.verbose = verbose;
        }
}

 

本文转自elbertchen 51CTO博客，原文链接：http://blog.51cto.com/linkyou/283240，如需转载请自行联系原作者