ActiveMQ入门示例

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。ActiveMQ 是Apache出品，最流行的，能力强劲的开源消息总线。ActiveMQ 是一个完全支持JMS1.1和J2EE 1.4规范的 JMS Provider实现。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();   
}




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);   
    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();   
}




JMS五种消息的发送/接收的例子

转自：http://chenjumin.javaeye.com/blog/687124  

1、消息发送

//连接工厂  
ConnectionFactory connFactory = new ActiveMQConnectionFactory(  
        ActiveMQConnection.DEFAULT_USER,  
        ActiveMQConnection.DEFAULT_PASSWORD,  
        "tcp://localhost:61616");  
 
//连接到JMS提供者  
Connection conn = connFactory.createConnection();  
conn.start();  
 
//事务性会话，自动确认消息  
Session session = conn.createSession(true, Session.AUTO_ACKNOWLEDGE);  
 
//消息的目的地  
Destination destination = session.createQueue("queue.hello");  
 
//消息生产者  
MessageProducer producer = session.createProducer(destination);  
producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT); //不持久化  
 
 
//文本消息  
TextMessage textMessage = session.createTextMessage("文本消息");  
producer.send(textMessage);  
 
//键值对消息  
MapMessage mapMessage = session.createMapMessage();  
mapMessage.setLong("age", new Long(32));  
mapMessage.setDouble("sarray", new Double(5867.15));  
mapMessage.setString("username", "键值对消息");  
producer.send(mapMessage);  
 
//流消息  
StreamMessage streamMessage = session.createStreamMessage();  
streamMessage.writeString("streamMessage流消息");  
streamMessage.writeLong(55);  
producer.send(streamMessage);  
 
//字节消息  
String s = "BytesMessage字节消息";  
BytesMessage bytesMessage = session.createBytesMessage();  
bytesMessage.writeBytes(s.getBytes());  
producer.send(bytesMessage);  
 
//对象消息  
User user = new User("cjm", "对象消息"); //User对象必须实现Serializable接口  
ObjectMessage objectMessage = session.createObjectMessage();  
objectMessage.setObject(user);  
producer.send(objectMessage);  
 
 
session.commit(); //在事务性会话中，只有commit之后，消息才会真正到达目的地  
producer.close();  
session.close();  
conn.close(); 




2、消息接收：通过消息监听器的方式接收消息


public class Receiver implements MessageListener{  
    private boolean stop = false;  
      
    public void execute() throws Exception {  
        //连接工厂  
        ConnectionFactory connFactory = new ActiveMQConnectionFactory(  
                ActiveMQConnection.DEFAULT_USER,  
                ActiveMQConnection.DEFAULT_PASSWORD,  
                "tcp://localhost:61616");  
          
        //连接到JMS提供者  
        Connection conn = connFactory.createConnection();  
        conn.start();  
          
        //事务性会话，自动确认消息  
        Session session = conn.createSession(true, Session.AUTO_ACKNOWLEDGE);  
          
        //消息的来源地  
        Destination destination = session.createQueue("queue.hello");  
          
        //消息消费者  
        MessageConsumer consumer = session.createConsumer(destination);  
        consumer.setMessageListener(this);  
          
        //等待接收消息  
        while(!stop){  
            Thread.sleep(5000);  
        }  
          
        session.commit();  
          
        consumer.close();  
        session.close();  
        conn.close();  
    }  
 
    public void onMessage(Message m) {  
        try{  
            if(m instanceof TextMessage){ //接收文本消息  
                TextMessage message = (TextMessage)m;  
                System.out.println(message.getText());  
            }else if(m instanceof MapMessage){ //接收键值对消息  
                MapMessage message = (MapMessage)m;  
                System.out.println(message.getLong("age"));  
                System.out.println(message.getDouble("sarray"));  
                System.out.println(message.getString("username"));  
            }else if(m instanceof StreamMessage){ //接收流消息  
                StreamMessage message = (StreamMessage)m;  
                System.out.println(message.readString());  
                System.out.println(message.readLong());  
            }else if(m instanceof BytesMessage){ //接收字节消息  
                byte[] b = new byte[1024];  
                int len = -1;  
                BytesMessage message = (BytesMessage)m;  
                while((len=message.readBytes(b))!=-1){  
                    System.out.println(new String(b, 0, len));  
                }  
            }else if(m instanceof ObjectMessage){ //接收对象消息  
                ObjectMessage message = (ObjectMessage)m;  
                User user = (User)message.getObject();  
                System.out.println(user.getUsername() + " _ " + user.getPassword());  
            }else{  
                System.out.println(m);  
            }  
              
            stop = true;  
        }catch(JMSException e){  
            stop = true;  
            e.printStackTrace();  
        }  
    }  
}