SpringBoot/Jackson 2.13.x - outputting standalone="yes" in XML Header

Question

I'm configuring my ObjectMapper/XmlMessageConverter in Spring Boot with the following Beans:

    @Bean
    public Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder()
    {
        final AnnotationIntrospector introspector = new JaxbAnnotationIntrospector(TypeFactory.defaultInstance());
        return new Jackson2ObjectMapperBuilder().serializationInclusion(JsonInclude.Include.NON_NULL).defaultUseWrapper(false)
                                                .annotationIntrospector(introspector);
    }
    
    @Bean
    @Autowired
    public MappingJackson2XmlHttpMessageConverter mappingJackson2XmlHttpMessageConverter(Jackson2ObjectMapperBuilder builder)
    {
        final XmlMapper xmlMapper = builder.createXmlMapper(true).build();
        xmlMapper.configure(ToXmlGenerator.Feature.WRITE_XML_DECLARATION, true);
        xmlMapper.getFactory().getXMLOutputFactory().setProperty(WstxOutputProperties.P_USE_DOUBLE_QUOTES_IN_XML_DECL, true);
        return new MappingJackson2XmlHttpMessageConverter(xmlMapper);
    }

But I can't seem to find a way for force the output of standalone="yes" into the xml header.

Does anyone know how I can do this?

Answer 1

Looks like jackson can do it only with a (custom) BufferingXmlWriter:

• https://www.google.com/search?q=xmlmapper+add+standalone
• https://stackoverflow.com/a/63505475/592355
• http://fasterxml.github.io/jackson-dataformat-xml/javadoc/2.13/com/fasterxml/jackson/dataformat/xml/ser/ToXmlGenerator.Feature.html

But you have "spring alternatives":

• Jaxb2RootElementHttpMessageConverter
• alternatively MarshallingHttpMessageConverter in combination with spring-oxm.

..can achieve it/have it as default.

• https://www.google.com/search?q=spring+boot+xml+standalone%3Dyes