RabbitMQ学习总结 第五篇:路由Routing
- Q1对所有橘色的(orange)的动物感兴趣;
- Q2希望能拿到所有兔子的(rabbit)信息,还有比较懒惰的(lazy.#)动物信息。
一条以” quick.orange.rabbit”为routing key的消息将会推送到Q1和Q2两个queue上,routing key为“lazy.orange.elephant”的消息同样会被推送到Q1和Q2上。但如果routing key为”quick.orange.fox”的话,消息只会被推送到Q1上;routing key为”lazy.brown.fox”的消息会被推送到Q2上,routing key为"lazy.pink.rabbit”的消息也会被推送到Q2上,但同一条消息只会被推送到Q2上一次。
如果在发送消息时所指定的exchange和routing key在消费者端没有对应的exchange和binding key与之绑定的话,那么这条消息将会被丢弃掉。例如:"orange"和"quick.orange.male.rabbit"。但是routing为”lazy.orange.male.rabbit”的消息,将会被推到Q2上。
Topic类型的exchange:
Topic类型的exchange是很强大的,也可以实现其它类型的exchange。
- 当一个队列被绑定为binding key为”#”时,它将会接收所有的消息,此时和fanout类型的exchange很像。
- 当binding key不包含”*”和”#”时,这时候就很像direct类型的exchange。
2、最终实现
我们准备在日志系统中使用topic类型的exchange。开始我们准备routing keys使用两个单词:"<facility>.<severity>"。代码和上篇博文里的差不多,EmitLogTopic.java:
public class EmitLogTopic { private static final String EXCHANGE_NAME = "topic_logs"; public static void main(String[] argv) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setHost("localhost"); Connection connection = factory.newConnection(); Channel channel = connection.createChannel(); //指定一个topic类型的exchange channel.exchangeDeclare(EXCHANGE_NAME, "topic"); //这里拿到routing key String routingKey = getRouting(argv); String message = getMessage(argv); channel.basicPublish(EXCHANGE_NAME, routingKey, null, message.getBytes()); System.out.println(" [x] Sent '" + routingKey + "':'" + message + "'"); connection.close(); } //... }
ReceiveLogsTopic.java的代码:
public class ReceiveLogsTopic { private static final String EXCHANGE_NAME = "topic_logs"; public static void main(String[] argv) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setHost("localhost"); Connection connection = factory.newConnection(); Channel channel = connection.createChannel(); //指定一个topic类型的exchange channel.exchangeDeclare(EXCHANGE_NAME, "topic"); String queueName = channel.queueDeclare().getQueue(); if (argv.length < 1){ System.err.println("Usage: ReceiveLogsTopic [binding_key]..."); System.exit(1); } //绑定binding key for(String bindingKey : argv){ channel.queueBind(queueName, EXCHANGE_NAME, bindingKey); } System.out.println(" [*] Waiting for messages. To exit press CTRL+C"); QueueingConsumer consumer = new QueueingConsumer(channel); channel.basicConsume(queueName, true, consumer); while (true) { QueueingConsumer.Delivery delivery = consumer.nextDelivery(); String message = new String(delivery.getBody()); String routingKey = delivery.getEnvelope().getRoutingKey(); System.out.println(" [x] Received '" + routingKey + "':'" + message + "'"); } } }
运行情况如下:
3、总结
在上边的基础上,只是丰富了routing key和binding key的写法。
参考链接:http://www.rabbitmq.com/tutorials/tutorial-five-java.html