How do I handle content-type null with Jackson2Jso

问题:

If it's not one problem, it's another... I seem to have gotten the 2 previous problems fixed but now when running outside of a test context, with a stood up application I see this.

o.s.a.s.c.Jackson2JsonMessageConverter   : Could not convert incoming message with content-type [null], 'json' keyword missing.

Like before, this message seems fairly clear. Heck, things even worked in a standalone test context, however when running in a standalone server the code seems to be taking a different path and is failing for the same reason but via a different component.

@Configuration
open class MessagingConfig {

    @Bean
    open fun jackson2Json(om: ObjectMapper): SmartMessageConverter {
        return Jackson2JsonMessageConverter(om)
    }

    @Bean
    open fun mappingJackson2(om: ObjectMapper): MappingJackson2MessageConverter {
        val mc = MappingJackson2MessageConverter()
        mc.objectMapper = om
        return mc
    }

    @Bean
    open fun defaultMessageHandlerMethodFactory(jackson: MappingJackson2MessageConverter): DefaultMessageHandlerMethodFactory {
        val factory = DefaultMessageHandlerMethodFactory()
        factory.setMessageConverter(jackson)
        return factory
    }


    @Bean
    open fun builder(): Jackson2ObjectMapperBuilderCustomizer {
        return Jackson2ObjectMapperBuilderCustomizer {
            it.modules(JavaTimeModule(), KotlinModule())
            it.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
        }
    }


    @Configuration
    open class RabbitConfigurer(val dmhmf: DefaultMessageHandlerMethodFactory) : RabbitListenerConfigurer {
        override fun configureRabbitListeners(registrar: RabbitListenerEndpointRegistrar?) {
            registrar?.messageHandlerMethodFactory = dmhmf
        }
    }
}

回答1:

You can add a MessagePostprocessor to the container factory to enhance the message with a content_id property.

factory.setAfterReceivePostProcessors(m -> {
    m.getMessageProperties().setContentId("application/json");
    return m;
}

回答2:

According the logic in the AbstractJackson2MessageConverter, the contentType AMQP property is required:

MessageProperties properties = message.getMessageProperties();
    if (properties != null) {
        String contentType = properties.getContentType();
        if (contentType != null && contentType.contains(this.supportedContentType.getSubtype())) {

I think we need to bring an improvement into this component do not be strict with it. The same way as we can do with the MappingJackson2MessageConverter via its:

/**
 * Whether this converter should convert messages for which no content type
 * could be resolved through the configured
 * {@link org.springframework.messaging.converter.ContentTypeResolver}.
 * <p>A converter can configured to be strict only when a
 * {@link #setContentTypeResolver contentTypeResolver} is configured and the
 * list of {@link #getSupportedMimeTypes() supportedMimeTypes} is not be empty.
 * <p>When this flag is set to {@code true}, {@link #supportsMimeType(MessageHeaders)}
 * will return {@code false} if the {@link #setContentTypeResolver contentTypeResolver}
 * is not defined or if no content-type header is present.
 */
public void setStrictContentTypeMatch(boolean strictContentTypeMatch) {

which is false by default.

Only the way to overcome the issue with missed contentType, but still proceed with the JSON message conversion, I see with a custom org.springframework.amqp.support.converter.AbstractMessageConverter implementation where you can combine a Jackson2JsonMessageConverter logic and don't care about missed contentType property.

Feel free to raise an issue against Spring AMQP to improve an AbstractJackson2MessageConverter!