Spring Integration http：outbound-gateway“没有合适的HttpMessageConverter”

Question

We are receiving the following error:

org.springframework.web.client.RestClientException: Could not write request:
  no suitable HttpMessageConverter found for
  request type [com.company.FileRecord] and
  content type [application/x-java-serialized-object]
    at org.springframework.web.client.RestTemplate$HttpEntityRequestCallback.doWithRequest(RestTemplate.java:770)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:549)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:527)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:472)
...

This is being thrown by an http:outbound-gateway with a MappingJackson2HttpMessageConverter attached, like so:

<bean id="jsonMessageConverter"
      class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
    <property name="supportedMediaTypes"
              value="application/x-java-serialized-object"/>
</bean>

<int:transformer input-channel="transformationChannel"
                 output-channel="registrationQueue"
                 ref="fileTransformer"/>

<int:channel id="registrationQueue"/>

<int-http:outbound-gateway id="gateway"
                           request-channel="registrationQueue"
                           message-converters="jsonMessageConverter"
                           url-expression="@urlGenerator.resolve()"
                           http-method="POST"
                           expected-response-type="javax.ws.rs.core.Response"
                           reply-channel="nullChannel"
                           error-handler="httpResponseErrorHandler"/>

Out object being serialized is annotated for Jackson serialization:

public class FileRecord {

    @JsonProperty
    private final String id;
    @JsonProperty
    private final String path;

    ...

}

I believe this was working with Spring Integration 2.2 and started to fail with a migration to 3.0.

It jumps out at me as odd that we are trying to serialize as application/x-java-serialized-object . I'd expect application/json here. Perhaps a header-enricher is called for? If so, I'd like to understand why exactly this needs to expressed. Shouldn't my jsonMessageConverter know this?

Answer 1

I'm not sure what the true cause or fix is, but I found a different approach which does the trick.

First, I removed the MappingJackson2HttpMessageConverter bean entirely.

I then added an extra transformer to explicitly convert my POJO to JSON:

<int:transformer input-channel="objectTransformationChannel"
                 output-channel="jsonTransformationChannel"
                 ref="fileTransformer"/>
<int:channel id="jsonTransformationChannel"/>
<int:object-to-json-transformer input-channel="jsonTransformationChannel"
                                output-channel="registrationQueue"/>
<int:channel id="registrationQueue"/>

For the outbound-gateway , I just needed to remove the message-converters as my payload is now JSON.

<int-http:outbound-gateway id="gateway"
                           request-channel="registrationQueue"
                           url-expression="@urlGenerator.resolve()"
                           http-method="POST"
                           expected-response-type="javax.ws.rs.core.Response"
                           reply-channel="nullChannel"
                           error-handler="httpResponseErrorHandler"/>

Answer 2

??

You are replacing the default supported (json) media types with this...

<property name="supportedMediaTypes"
          value="application/x-java-serialized-object"/>

...the constructor sets them up properly...

public MappingJackson2HttpMessageConverter() {
    super(new MediaType("application", "json", DEFAULT_CHARSET),
            new MediaType("application", "*+json", DEFAULT_CHARSET));
}

Just remove...

<property name="supportedMediaTypes"
          value="application/x-java-serialized-object"/>

...and you should be good.