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Question

我正在尝试在kafka上使用spring-cloud-stream。下面是示例代码。但它似乎没有任何作用。它总是创建一个名为 "output "的主题。但是值没有被发布。

应用程序.yaml

spring.cloud.stream:
  function:
    definition: streamSupplier
  bindings:
    streamSupplier-out-0:
      destination: numbers

我的目标是只产生数值。

@SpringBootApplication
@EnableBinding(Source.class)
public class CloudStreamDemoApplication {

    private AtomicInteger atomicInteger = new AtomicInteger();
    public static void main(String[] args) {
        SpringApplication.run(CloudStreamDemoApplication.class, args);
    }

    @Bean
    public Supplier<Integer> streamSupplier(){
        return () -> {
            System.out.println("Publishing : " + atomicInteger.incrementAndGet());
            return atomicInteger.get();
        };
    }
}

依赖性 - 2.2.6.RELEASE

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-stream</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-stream-binder-kafka</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka</artifactId>
    </dependency>

Answer 1

你需要删除 @EnableBinding(Source.class) 的类。如果存在这种情况，功能绑定将不会发生。

Answer 2

注释@EnableBinding导致了上述问题。

请阅读下面来自spring Docs的摘录。

Unlike previous versions of spring-cloud-stream which relied on @EnableBinding and @StreamListener annotations, the above example looks no different then any vanilla spring-boot application. It defines a single bean of type Function and that it is. So, how does it became spring-cloud-stream application? It becomes spring-cloud-stream application simply based on the presence of spring-cloud-stream and binder dependencies and auto-configuration classes on the classpath effectively setting the context for your boot application as spring-cloud-stream application. And in this context beans of type Supplier, Function or Consumer are treated as defacto message handlers triggering binding of to destinations exposed by the provided binder following certain naming conventions and rules to avoid extra configuration.