Support Jackson2 based XML serialization/deserialization [SPR-11785]

[spring-projects-issues]

Sébastien Deleuze opened SPR-11785 and commented

It is basically a MappingJackson2HttpMessageConverter where we register a JacksonXmlModule. It could allow users to setup easily a XML + JSON webservice supporting filtering thanks to JsonView.

It is also a nice alternative to Jaxb2 since it allows to get XML support without @XmlRootElement annotations.

It would not impact existing Jaxb2 support since it can be activated only if JacksonXmlModule class from jackson-dataformat-xml JAR module is detected on the classpath.

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Issue Links:

• Support Jackson based XML serialization in RestTemplate [SPR-12225] #16840 Support Jackson based XML serialization in RestTemplate
• Integrate Jackson @JsonView [SPR-7156] #11815 Integrate Jackson @JsonView
• Create builder for Jackson ObjectMapper [SPR-12243] #16857 Create builder for Jackson ObjectMapper
• AllEncompassingFormHttpMessageConverter does not prefer Jackson2 over JAXB for XML marshalling [SPR-13240] #17831 AllEncompassingFormHttpMessageConverter does not prefer Jackson2 over JAXB for XML marshalling

Referenced from: commits ebc726a, 6665634

[spring-projects-issues]

Juergen Hoeller commented

Could we also do this as a flag on MappingJackson2HttpMessageConverter itself, or even let it happen automatically there if jackson-dataformat-xml is on the classpath?

Juergen

[spring-projects-issues]

Sébastien Deleuze commented

We could, and it was in fact my first intention. But MappingJackson2HttpMessageConverter package is org.springframework.http.converter.json, and I was not confortable with the idea to put XML related functionalities in it.

That's why I ended up with the following proposal:

• Common code in org.springframework.http.converter.AbstractMappingJackson2HttpMessageConverter
• JSON converter : org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
• XML converter : org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter
• +1 for automatic registration when jackson-dataformat-xml is in the classpath

If we could move MappingJackson2HttpMessageConverter to org.springframework.http.converter package, staying with a single class would be perfect, but I don't know if we can do a such breaking change. Do you think we could, or is it fine for you to put XML related code in org.springframework.http.converter.json.MappingJackson2HttpMessageConverter ?

[spring-projects-issues]

Juergen Hoeller commented

Fair enough, that's a good point. However, given the options, I'd rather put the support into MappingJackson2HttpMessageConverter itself, interpreting the subpackage name as "primarily json oriented providers" (or as an abbreviation for j-ack-son) ;-) Seriously, I don't think it's worth a convoluted split here, in particular given that Jackson2ObjectMapperFactoryBean lives in the json subpackage as well and is probably equally useful for the jackson-dataformat-xml case.

Juergen

[spring-projects-issues]

Sébastien Deleuze commented

Thanks for your feedback ! Thinking more about that, Jackson itself use a lot of JSON historically related stuff (including configuration options) for XML serialization, so yes it is better to add support in existing MappingJackson2HttpMessageConverter. It may allow us to add other formats supported by Jackson more easily later if we want to.

I have updated the issue title accordingly.