rabbitMQ之发布/订阅

发布消息：

public class EmitLog {

    private static final String EXCHANGE_NAME = "logs";

    public static void main(String[] argv)
                  throws java.io.IOException {

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.exchangeDeclare(EXCHANGE_NAME, "fanout");

        String message = getMessage(argv);

        channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes());
        System.out.println(" [x] Sent '" + message + "'");

        channel.close();
        connection.close();
    }
    //...
}

 

订阅消息：

public class ReceiveLogs {
  private static final String EXCHANGE_NAME = "logs";

  public static void main(String[] argv) throws Exception {
    ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("localhost");
    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();

    channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
    String queueName = channel.queueDeclare().getQueue();
    channel.queueBind(queueName, EXCHANGE_NAME, "");

    System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

    Consumer consumer = new DefaultConsumer(channel) {
      @Override
      public void handleDelivery(String consumerTag, Envelope envelope,
                                 AMQP.BasicProperties properties, byte[] body) throws IOException {
        String message = new String(body, "UTF-8");
        System.out.println(" [x] Received '" + message + "'");
      }
    };
    channel.basicConsume(queueName, true, consumer);
  }
}

 订阅可以分为持久订阅和非持久订阅，对于持久订阅的消费者，在队列声明时，要声明为持久队列

channel.queueDeclare(queueName, true, false, false, null);

 持久订阅的队列在rabbitmq服务器重启的情况下，还可以继续持有该队列数据

非持久订阅队列在服务器重启的情况下，会失去所有未消费的队列数据

注意：由于是发布/订阅模式，所以在exchange绑定时是不需要指定routingKey的

channel.queueBind(queueName, Constants.EXCHANGE_FANT, "");