How can we configure the internal Jackson mapper when using RestTemplate?

Question

I want to update the SerializationConfig.Feature... properties of the jackson mapper used by Spring RestTemplate, Any idea how I can get to it or where I can/should configure it.

Answer 1

The default RestTemplate constructor registers a set of HttpMessageConverters:

this.messageConverters.add(new ByteArrayHttpMessageConverter()); this.messageConverters.add(new StringHttpMessageConverter()); this.messageConverters.add(new ResourceHttpMessageConverter()); this.messageConverters.add(new SourceHttpMessageConverter()); this.messageConverters.add(new XmlAwareFormHttpMessageConverter()); if (jaxb2Present) {     this.messageConverters.add(new Jaxb2RootElementHttpMessageConverter()); } if (jacksonPresent) {     this.messageConverters.add(new MappingJacksonHttpMessageConverter()); } if (romePresent) {     this.messageConverters.add(new AtomFeedHttpMessageConverter());     this.messageConverters.add(new RssChannelHttpMessageConverter()); } 

The MappingJacksonHttpMessageConverter in turns, creates ObjectMapper instance directly. You can either find this converter and replace ObjectMapper or register a new one before it. This should work:

@Bean public RestOperations restOperations() {     RestTemplate rest = new RestTemplate();     //this is crucial!     rest.getMessageConverters().add(0, mappingJacksonHttpMessageConverter());     return rest; }  @Bean public MappingJacksonHttpMessageConverter mappingJacksonHttpMessageConverter() {     MappingJacksonHttpMessageConverter converter = new MappingJacksonHttpMessageConverter();     converter.setObjectMapper(myObjectMapper());     return converter; }  @Bean public ObjectMapper myObjectMapper() {     //your custom ObjectMapper here } 

In XML it is something along these lines:

<bean id="restOperations" class="org.springframework.web.client.RestTemplate">     <property name="messageConverters">         <util:list>             <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>             <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>             <bean class="org.springframework.http.converter.ResourceHttpMessageConverter"/>             <bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter"/>             <bean class="org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter"/>             <bean class="org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter"/>             <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">                 <property name="objectMapper" ref="customObjectMapper"/>             </bean>         </util:list>     </property> </bean>  <bean id="customObjectMapper" class="org.codehaus.jackson.map.ObjectMapper"/> 

Note that the transition isn't really 1:1 - I have to explicitly create messageConverters list in XML while with @Configuration approach I could reference existing one and simply modify it. But this should work.

Answer 2

If you are not using Spring IOC, you can do something like this (Java 8):

ObjectMapper objectMapper = new ObjectMapper(); // configure your ObjectMapper here  RestTemplate restTemplate = new RestTemplate();      MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter(); messageConverter.setPrettyPrint(false); messageConverter.setObjectMapper(objectMapper); restTemplate.getMessageConverters().removeIf(m -> m.getClass().getName().equals(MappingJackson2HttpMessageConverter.class.getName())); restTemplate.getMessageConverters().add(messageConverter);