java - 是否可以在@RabbitListener 上设置预取计数

Question

我知道可以制作 SimpleMessageListenerContainer bean 并在此处设置预取计数和消息监听器，如下所示:

@Bean
public SimpleMessageListenerContainer messageListenerContainer(
        ConnectionFactory rabbitConnectionFactory,
        Receiver receiver) {
    SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
    container.setConnectionFactory(rabbitConnectionFactory);
    container.setQueueNames("hello");
    container.setMessageListener(new MessageListenerAdapter(receiver, "receive"));
    container.setPrefetchCount(1000);
    return container;
}

但是，如果我想使用 @RabbitListener 的声明式方法，如何设置 channel 的预取计数？

@Component
public class Receiver {

    private static final Logger log = LoggerFactory.getLogger(Receiver.class);

    @RabbitListener(queues = "hello") // how to set prefetch count here?
    public void receive(String message) {
        log.info(" [x] Received '{}'.", message);
    }

}

这不可能吗？

Answer 1

根据@artem-bilan 回答的解决方案:

在某些 @Configuration 类中声明 RabbitListenerContainerFactory 预取计数为 10 的 bean:

@Bean
public RabbitListenerContainerFactory<SimpleMessageListenerContainer> prefetchTenRabbitListenerContainerFactory(ConnectionFactory rabbitConnectionFactory) {
    SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
    factory.setConnectionFactory(rabbitConnectionFactory);
    factory.setPrefetchCount(10);
    return factory;
}

Receiver bean 使用这个工厂 bean:

@Component
public class Receiver {

    private static final Logger log = LoggerFactory.getLogger(Receiver.class);

    @RabbitListener(queues = "hello", containerFactory = "prefetchTenRabbitListenerContainerFactory")
    public void receive(String message) {
        log.info(" [x] Received '{}'.", message);
    }

    @RabbitListener(queues = "hello")
    public void receiveWithoutPrefetch(String message) {
        log.info(" [x] Received without prefetch '{}'.", message);
    }

}

此处的两个监听器仅用于演示目的。
使用此配置，Spring 创建了两个 AMQP channel 。每个 @RabbitListener 一个。首先使用我们新的 prefetchTenRabbitListenerContainerFactory bean 预取计数 10，第二个使用默认 rabbitListenerContainerFactory bean 预取计数 1。