Question

我正在尝试使用Spring Cloud Stream Kafka Binding来发送和接收本地zookeeper和kafka服务器的消息。但是，在启动Spring MVC服务器时，我看到以下异常：

Caused by: org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers
at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:154) ~[spring-integration-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:121) ~[spring-integration-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:77) ~[spring-integration-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
... 28 common frames omitted

服务器非常简单，一个类和一个spring应用程序属性文件：

package com.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.PostConstruct;
import java.util.Map;

@RestController
@EnableBinding(ProducerChannels.class)
@SpringBootApplication
public class ProducerApplication {

  private final MessageChannel consumer;

  public ProducerApplication(ProducerChannels channels){
      this.consumer = channels.consumer();
  }

  @PostMapping("/greet/{name}")
  public void publish(@RequestBody Map<String, String> name){
      String greeting = "Hello, " + name + "!";

      Message<String> msg = MessageBuilder.withPayload(greeting).build();

      consumer.send(msg);
  }

  public static void main(String[] args) {
      SpringApplication.run(ProducerApplication.class, args);
  }
}

interface ProducerChannels {

  @Output
  MessageChannel consumer();
}

块引用 spring.cloud.stream.kafka.bindings.consumer.destination = consumer server.port = 8080

配置Spring Cloud Stream还需要做些什么？

Answer 1

您使用的是哪个版本？我只是将你的代码粘贴到一个启动1.4.2应用程序（1.1.0.RELEASE为流启动器），它对我来说很好。

Answer 2

消费者是一个特殊的关键字。你不应该使用它。我认为，如果您按照以下说明进行修复，将会发生这种情况。

if ! [[ -d "$AEM_SEGMENTSTORE_LOCATION" && -d "$AEM_SEGMENTSTORE_LOCATION_AZURE" ]]; then
    echo "not found"
fi

application.yml文件

public interface ProducerChannels {
    
    String OUTPUT = "example-topic";

    @Output(OUTPUT)
    MessageChannel exampleTopic();
}

或

spring:
  cloud:
    stream:
      kafka:
        binder:
          brokers: localhost:9092
      bindings:
        example-topic:
          destination: example-topic
          contentType: application/json

Spring Cloud Stream Kafka：org.springframework.integration.MessageDispatchingException：Dispatcher没有订阅者

2 个答案: