rabbitmq入门-主题

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) {}
      }
    }
  }
}