Spring integration spring集成中的尝试与建议

我创建了一个简单的示例来了解重试和建议。以下是示例配置：

@Configuration
@EnableIntegration
@IntegrationComponentScan
@ComponentScan
public class SimpleConfiguration2 {
  @Bean
  public DirectChannel requestChannel() {
   return new DirectChannel();
  }

  @Bean
  public DirectChannel aChannel() {
   return new DirectChannel();
  }

  @Bean
  public DirectChannel retryLaterChannel() {
   return new DirectChannel();
  }

  @Bean
  public DirectChannel tapChannel() {
   return new DirectChannel();
  }

  @Bean
  public DirectChannel endChannel() {
   return new DirectChannel();
  }

  @Bean
  public ExceptionThrowingTransformer exceptionThrowingTransformer() {
    return new ExceptionThrowingTransformer();
  }

  @Bean
  public IntegrationFlow initFlow() {
    return IntegrationFlows.from(requestChannel())
                           .gateway(aChannel(), e -> e.advice(retryAdvice())
                                                      .errorChannel(retryLaterChannel()))
                           .get();
  }

  @Bean
  public Advice retryAdvice() {
    final RequestHandlerRetryAdvice advice = new RequestHandlerRetryAdvice();
    advice.setRetryTemplate(retryTemplate());
    return advice;
  }

  @Bean
  public RetryTemplate retryTemplate() {
    final RetryTemplate ret = new RetryTemplate();
    ret.setRetryPolicy(retryPolicy());
    ret.setThrowLastExceptionOnExhausted(false);
    return ret;
  }

  @Bean
  public RetryPolicy retryPolicy() {
    final Map<Class<? extends Throwable>, Boolean> map = new HashMap<Class<? extends Throwable>, Boolean>() {{
        put(RuntimeException.class, true);
      }
      private static final long serialVersionUID = -1L;
    };
    final RetryPolicy ret = new SimpleRetryPolicy(3, map, true);
    return ret;
  }

  @Bean
  public IntegrationFlow aChannelFlow() {
    return IntegrationFlows.from(aChannel())
                           .transform("C: "::concat)
                           .transform(exceptionThrowingTransformer())
                           .channel(endChannel())
                           .get();
  }

  @Bean
  public IntegrationFlow endFlow() {
    return IntegrationFlows.from(endChannel())
                           .handle(String.class, (p, h) -> p)
                           .get();
  }

  @Bean
  public IntegrationFlow retryLaterFlow() {
    return IntegrationFlows.from(retryLaterChannel())
                           .wireTap(tapChannel())
//                           .bridge(null)
//                           .handle(String.class, (p, h) -> p)
                           .get();
  }

  @Bean
  public IntegrationFlow tapFlow() {
    return IntegrationFlows.from(tapChannel())
                           .handle(m -> System.err.println("tap [" + Thread.currentThread().getName() + "] " + m.getPayload() ))
                           .get();
  }
}

和回音网关：

@MessagingGateway(defaultReplyTimeout=600)
public interface EchoGateway {
  @Gateway(requestChannel = "requestChannel")
  String echo(String message);
}

问题1： 如果按原样运行代码，对于放置在requestChannel上的输入“MSG1”，我将获得以下输出：

main ExceptionThrowingTransformer will fail 1 more times
tap [main] org.springframework.integration.transformer.MessageTransformationException: ; nested exception is org.springframework.messaging.MessageHandlingException: ; nested exception is java.lang.RuntimeException
main ExceptionThrowingTransformer last failure
tap [main] org.springframework.integration.transformer.MessageTransformationException: ; nested exception is org.springframework.messaging.MessageHandlingException: ; nested exception is java.lang.RuntimeException
main C: MSG1

而我希望看到的是：

main ExceptionThrowingTransformer will fail 1 more times
main ExceptionThrowingTransformer last failure
main C: MSG1

重试会发生，但原始异常仍会传播到initFlow网关中指定的errorChannel。有没有办法防止这种情况发生

问题2： 当numFail更改为3时，除了问题1中的输出外，还会向调用者返回一个异常：

org.springframework.messaging.MessagingException: failure occurred in error-handling flow; nested exception is org.springframework.messaging.MessageDeliveryException: Dispatcher has no subscribers for channel 'application:-1.retryLaterChannel'.; nested exception is org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers

如果只有retryLaterFlow中的第一条注释未注释，则exceptionThrowingTransformer引发的异常将返回给调用方。 既然retryTemplate已经设置了setThrowLastExceptionOnExhausted（false），为什么会这样

问题3： 如果retryLaterFlow中只有第二条注释未注释，则输出如下所示：

main ExceptionThrowingTransformer  will fail 2 more times
tap [main] org.springframework.integration.transformer.MessageTransformationException: ; nested exception is org.springframework.messaging.MessageHandlingException: ; nested exception is java.lang.RuntimeException
org.springframework.integration.transformer.MessageTransformationException: ; nested exception is org.springframework.messaging.MessageHandlingException: ; nested exception is java.lang.RuntimeException

为什么重试没有生效？（对问题1的回答也可以回答此问题）

您有两个网关（初始和中流），您正在建议中流网关，以便它按预期工作

您应该建议变压器获得您期望的结果

org.springframework.messaging.MessagingException: failure occurred in error-handling flow; nested exception is org.springframework.messaging.MessageDeliveryException: Dispatcher has no subscribers for channel 'application:-1.retryLaterChannel'.; nested exception is org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers

main ExceptionThrowingTransformer  will fail 2 more times
tap [main] org.springframework.integration.transformer.MessageTransformationException: ; nested exception is org.springframework.messaging.MessageHandlingException: ; nested exception is java.lang.RuntimeException
org.springframework.integration.transformer.MessageTransformationException: ; nested exception is org.springframework.messaging.MessageHandlingException: ; nested exception is java.lang.RuntimeException