Spring Cloud @SqsListener MessageConversionException：无法从 [java.lang.String] 转换为 GenericMessage

Question

我在尝试使用 SQS 消息时看到以下异常：

org.springframework.messaging.converter.MessageConversionException: 

Cannot convert from [java.lang.String] to [com.example.demo.Foo] for GenericMessage [payload={}, headers={LogicalResourceId=my-queue, ApproximateReceiveCount=1, SentTimestamp=1529021258825, ReceiptHandle=xxxx, Visibility=org.springframework.cloud.aws.messaging.listener.QueueMessageVisibility@47ce6922, SenderId=xxxx, lookupDestination=my-queue, ApproximateFirstReceiveTimestamp=1529021264456, MessageId=xxxx}]
    at org.springframework.messaging.handler.annotation.support.PayloadArgumentResolver.resolveArgument(PayloadArgumentResolver.java:144)
    at org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:116)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:137)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:109)
    at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMatch(AbstractMethodMessageHandler.java:515)
    at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessageInternal(AbstractMethodMessageHandler.java:473)
    at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessage(AbstractMethodMessageHandler.java:409)
    at org.springframework.cloud.aws.messaging.listener.SimpleMessageListenerContainer.executeMessage(SimpleMessageListenerContainer.java:205)
    at org.springframework.cloud.aws.messaging.listener.SimpleMessageListenerContainer$MessageExecutor.run(SimpleMessageListenerContainer.java:342)
    at org.springframework.cloud.aws.messaging.listener.SimpleMessageListenerContainer$SignalExecutingRunnable.run(SimpleMessageListenerContainer.java:397)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

Spring Boot 代码如下：

@Configuration
@EnableSqs
public class AmazonSqsConfiguration {

    @Bean
    public AmazonSQS amazonSQSAsync() {
        return AmazonSQSAsyncClientBuilder.standard()
            .withRegion(Regions.US_WEST_2)
            .build();
    }
}

@Service
public class MyService {

    // Throws MessageConversionException
    @SqsListener("my-queue")
    public void listen(Foo payload) {

    }

    // Works fine
    @SqsListener("my-queue")
    public void listen(String payload) {

    }
}

我正在使用org.springframework.cloud:spring-cloud-aws-messaging:2.0.0.RC2

我的类路径中确实有 Jackson 2 库，因此 PayloadArgumentResolver 正在尝试使用 MappingJackson2MessageConverter 反序列化我的消息负载。但是，由于 SQS 消息缺少 contentType 标头并且 strictContentTypeMatch 设置为 true，所以 canConvertFrom 返回 false。

https://github.com/spring-projects/spring-framework/blob/f5e8f4983f7653169f3da8a3287499fce93cadd4/spring-messaging/src/main/java/org/springframework/messaging/converter/AbstractMessageConverter.java#L237

我看不到如何为 SQS 消息设置 contentType 标头 - 我错过了什么吗？

Spring Cloud QueueMessageHandler 是否应该将 strictContentTypeMatch 设置为 true？

https://github.com/spring-cloud/spring-cloud-aws/blob/6a7c3c31709d4239131b27936de29385df414d41/spring-cloud-aws-messaging/src/main/java/org/springframework/cloud/aws/messaging/listener/QueueMessageHandler.java#L217

Answer 1

遇到同样的问题，我会根据谁生成消息以两种方式之一回答问题

• 是的，可以在消息上设置contentType，如果您控制正在生成的消息，这是首选。在 AWS 控制台中，当您手动发送消息时，有一个“消息属性”选项卡。您将添加名称为contentType 和值application/json 的属性。 AWS SDK 调用应该允许您从应用程序代码中执行相同的操作。

• 对于 AWS 生成的没有指定内容类型的消息，例如 S3 事件，您实际上需要将 strictContentMatch 设置为 false。这记录在这里： http://cloud.spring.io/spring-cloud-static/spring-cloud-aws/2.0.0.RELEASE/multi/multi__messaging.html#_consuming_aws_event_messages_with_amazon_sqs

该文档令人困惑，因为它说“没有 mime 类型的标题”，但标题的实际名称是 contentType，正如您自己发现的那样。

Answer 2

在“发送”和“收听”方法中都有一个一致的转换器：

/** Provides a deserialization template for incoming SQS messages */
@Bean
public QueueMessageHandlerFactory queueMessageHandlerFactory(MessageConverter messageConverter) {

    var factory = new QueueMessageHandlerFactory();
    factory.setArgumentResolvers(singletonList(new PayloadArgumentResolver(messageConverter)));
    return factory;
}

/** Provides a serialization template for outgoing SQS messages */
@Bean
public QueueMessagingTemplate queueMessagingTemplate(AmazonSQSAsync amazonSQSAsync, MessageConverter messageConverter) {
    return new QueueMessagingTemplate(amazonSQSAsync, (ResourceIdResolver) null, messageConverter);
}

/** Provides JSON converter for SQS messages */
@Bean
protected MessageConverter messageConverter(ObjectMapper objectMapper) {

  var converter = new MappingJackson2MessageConverter();
  converter.setObjectMapper(objectMapper);
  // Serialization support:
  converter.setSerializedPayloadClass(String.class);
  // Deserialization support: (suppress "contentType=application/json" header requirement)
  converter.setStrictContentTypeMatch(false);
  return converter;
}

在原始接受的答案中查看详细信息。感谢@wrschneider。

注意：上面的例子注入并设置了 ObjectMapper。对于 HTTP REST 控制器的一致性（如果有），这是可选的。

---

进口：

import static java.util.Collections.singletonList;

import com.amazonaws.services.sqs.AmazonSQSAsync;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cloud.aws.core.env.ResourceIdResolver;
import org.springframework.cloud.aws.messaging.config.QueueMessageHandlerFactory;
import org.springframework.cloud.aws.messaging.core.QueueMessagingTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.messaging.converter.MessageConverter;
import org.springframework.messaging.handler.annotation.support.PayloadArgumentResolver;

---

用法：

  @SqsListener("my-queue")
  public void listen(Foo payload) {

  }

  public void send(Foo dto) {
    queueMessagingTemplate.convertAndSend(url, dto);
  }