使用spring集成kafka，我们仍然可以使用@messaginggateway和@gateway。
我当前的代码如下所示：

@MessagingGateway
public interface OrderGateway {
 @Gateway(requestChannel = "requestChannel", replyChannel = "replyChannel",headers = {@GatewayHeader(name = "kafka_topic", value ="requestTopic"))
  Order order(Item item)
}

在我的spring配置中：

@Bean
@ServiceActivator(inputChannel = "requestChannel")
public MessageHandler kafkaMessageHandler(KafkaTemplate kafkaTemplate) {
    KafkaProducerMessageHandler<String, String> messageHandler = new KafkaProducerMessageHandler<>(kafkaTemplate);
    messageHandler.setMessageKeyExpression(new LiteralExpression("spring-integration-kafka"));
    messageHandler.setTopicExpression(new SpelExpressionParser().parseExpression("headers.kafka_topic"));
    return messageHandler;
}

在这个设置中，我得到了一个错误消息：

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