Spring集成错误“没有可用的输出通道或回复通道头"

我不知道为什么会出现异常

I am not sure why I am getting the exception

Caused by: org.springframework.messaging.core.DestinationResolutionException: no output-channel or replyChannel header available

它只是一个简单的 IntegrationFlow，但不确定我在下面的代码中缺少什么.

Its just a simple IntegrationFlow but not sure what am I missing here in the code below.

  @Bean
  Exchange messageExchange() {
    return ExchangeBuilder
        .directExchange("attr")
        .durable(true)
        .build();
  }

  @Bean
  Queue queue() {
    return QueueBuilder
        .durable("attr_queue")
        .build();
  }

  @Bean
  Binding binding() {
    return BindingBuilder
        .bind(queue())
        .to(messageExchange())
        .with("attr_queue")
        .noargs();
  }

  @Bean
  IntegrationFlow deltaFlow(ConnectionFactory connectionFactory) {
    return IntegrationFlows.from(Amqp
        .inboundAdapter(connectionFactory, queue()))
        .handle(String.class, (payload, headers) -> {
          if (payload.isEmpty()) {
            log.info("Payload empty");
          } else {
            log.info("Payload : " + payload);
          }
          return payload;
        })
        .get();
  }

我试图接触 Spring Integration，但不确定为什么会出现此异常.我要做的就是使用 inboundAdapter 从队列中读取数据，然后将其记录到控制台.代码运行良好，但是当我向队列发布消息时，出现此异常.使用 Amqp 适配器时是否必须始终指定 replyChannel 或 output-channel ?

I was trying to get my hands on Spring Integration and was not sure why I am getting this exception. All I'm trying to do is to read from a queue using an inboundAdapter and just log it to the console. The code runs fine, but when I publish a message to the queue, I get this exception. Do I have to specify a replyChannel or output-channel always when using Amqp adapters?