direct类型的交换器(exchange),交换器将会对binding key和routing key进行精确匹配,从而确定消息该分发到哪个队列。
topic类型的交换器,通过设置routing key,交换器匹配其表达式,从而确认消息分发的队列。
topic类型交换器不能声明任意的routing key,它的组成是一系列的words,不同word之间使用分隔符分开。word可以是任意单词,通常是有意义的描述。如:"stock.usd.nyse", "nyse.vmw","quick.orange.rabbit",最长是255字节。
routing key可以有通配符组成:
*:匹配一个word #:配置0个或多个word
如上图:
Q1将绑定“*.orange.*”
Q2将绑定“*.*.rabbit”与"lzay.*"
一条消息的routing key 满足 "quick.orge.rabbit"将匹配Q1与Q2
“lazy.orange.elephant”也同时满足Q1、Q2
同理,按照规范配置就OK。
生产者代码
public class EmitLogTopic { private static final String EXCHANGE_NAME = "topic_logs"; public static void main(String[] argv) { Connection connection = null; Channel channel = null; try { ConnectionFactory factory = new ConnectionFactory(); factory.setHost("localhost"); connection = factory.newConnection(); channel = connection.createChannel(); channel.exchangeDeclare(EXCHANGE_NAME, "topic"); String routingKey = getRouting(argv); String message = getMessage(argv); channel.basicPublish(EXCHANGE_NAME, routingKey, null, message.getBytes()); System.out.println(" [x] Sent '" + routingKey + "':'" + message + "'"); } catch (Exception e) { e.printStackTrace(); } finally { if (connection != null) { try { connection.close(); } catch (Exception ignore) {} } } } private static String getRouting(String[] strings){ if (strings.length < 1) return "anonymous.info"; return strings[0]; } private static String getMessage(String[] strings){ if (strings.length < 2) return "Hello World!"; return joinStrings(strings, " ", 1); } private static String joinStrings(String[] strings, String delimiter, int startIndex) { int length = strings.length; if (length == 0 ) return ""; if (length < startIndex ) return ""; StringBuilder words = new StringBuilder(strings[startIndex]); for (int i = startIndex + 1; i < length; i++) { words.append(delimiter).append(strings[i]); } return words.toString(); } }
消费者代码
public class ReceiveLogsTopic { private static final String EXCHANGE_NAME = "topic_logs"; public static void main(String[] argv) { Connection connection = null; Channel channel = null; try { ConnectionFactory factory = new ConnectionFactory(); factory.setHost("localhost"); connection = factory.newConnection(); channel = connection.createChannel(); channel.exchangeDeclare(EXCHANGE_NAME, "topic"); String queueName = channel.queueDeclare().getQueue(); if (argv.length < 1){ System.err.println("Usage: ReceiveLogsTopic [binding_key]..."); System.exit(1); } 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 + "'"); } } catch (Exception e) { e.printStackTrace(); } finally { if (connection != null) { try { connection.close(); } catch (Exception ignore) {} } } } }