[java] Spring configure @ResponseBody JSON format

Imagine I have this annotated method in a Spring 3 @Controller

@RequestMapping("")
public @ResponseBody MyObject index(@RequestBody OtherObject obj) {
    MyObject result = ...;
    return result;
}

But I need to configure the output json format, just as if I were doing:

ObjectMapper om = new ObjectMapper();
om.configure(JsonGenerator.Feature.QUOTE_FIELD_NAMES, true);
om.getSerializationConfig()
        .setSerializationInclusion(JsonSerialize.Inclusion.NON_DEFAULT);
om.getSerializationConfig()
        .set(SerializationConfig.Feature.INDENT_OUTPUT, false);

Is there any way to configure this behaviour?

I've found a couple of related questions, but I am not sure about how to adapt them to my specific case:

1. spring prefixjson with responsebody
2. Who sets response content-type in Spring MVC (@ResponseBody)

Thank you !

For the folks who are using Java based Spring configuration:

@Configuration
@ComponentScan(basePackages = "com.domain.sample")
@EnableWebMvc
public class SpringConfig extends WebMvcConfigurerAdapter {
....

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        final ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        converter.setObjectMapper(objectMapper);
        converters.add(converter);
        super.configureMessageConverters(converters);
    }

....

}

I'm using MappingJackson2HttpMessageConverter - which is from fasterxml.

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.3.1</version>
</dependency>

If you want to use codehaus-jackson mapper, instead use this one MappingJacksonHttpMessageConverter

 <dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-asl</artifactId>
    <version>${codehaus.jackson.version}</version>
 </dependency>

Take a look at Rick Hightower's approach. His approach avoids configuring ObjectMapper as a singleton and allows you to filter the JSON response for the same object in different ways per each request method.

http://www.jroller.com/RickHigh/entry/filtering_json_feeds_from_spring

You can do the following(jackson version < 2):

Custom mapper class:

import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize;

public class CustomObjectMapper extends ObjectMapper {
    public CustomObjectMapper() {
        super.configure(JsonGenerator.Feature.QUOTE_FIELD_NAMES, true);
        super.getSerializationConfig()
                .setSerializationInclusion(JsonSerialize.Inclusion.NON_DEFAULT);
        super.getSerializationConfig()
                .set(SerializationConfig.Feature.INDENT_OUTPUT, false);
    }
}

Spring config:

<mvc:annotation-driven>
    <mvc:message-converters register-defaults="false">
        <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
            <property name="objectMapper">
                <bean class="package.CustomObjectMapper"/>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

Yes but what happens if you start using mixins for example, you cant be having ObjectMapper as a singleton because you will be applying the configuration globally. So you will be adding or setting the mixin classes on the same ObjectMapper instance?

I wrote my own FactoryBean which instantiates an ObjectMapper (simplified version):

 public class ObjectMapperFactoryBean implements FactoryBean<ObjectMapper>{

        @Override
        public ObjectMapper getObject() throws Exception {
                ObjectMapper mapper = new ObjectMapper();
                mapper.getSerializationConfig().setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL);
                return mapper;
        }

        @Override
        public Class<?> getObjectType() {
                return ObjectMapper.class;
        }

        @Override
        public boolean isSingleton() {
                return true;
        }

}

And the usage in the spring configuration:

<bean
    class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <list>
            <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
                <property name="objectMapper" ref="jacksonObjectMapper" />
            </bean>
        </list>
    </property>
</bean>

For Spring version 4.1.3+

I tried Jama's solution, but then all responses were returned with Content-type 'application/json', including the main, generated HTML page.

Overriding configureMessageConverters(...) prevents spring from setting up the default converters. Spring 4.1.3 allows modification of already configured converters by overriding extendMessageConverters(...):

@Configuration
public class ConverterConfig extends WebMvcConfigurerAdapter {
    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        for (HttpMessageConverter<?> converter : converters) {
            if (converter instanceof AbstractJackson2HttpMessageConverter) {
                AbstractJackson2HttpMessageConverter c = (AbstractJackson2HttpMessageConverter) converter;
                ObjectMapper objectMapper = c.getObjectMapper();
                objectMapper.setSerializationInclusion(Include.NON_NULL);
            }
        }

        super.extendMessageConverters(converters);
    }
}

see org.springframework..WebMvcConfigurationSupport#getMessageConverters()

see org.springframework..WebMvcConfigurationSupport#addDefaultHttpMessageConverters(...)

You can configure the ObjectMapper as a bean in your Spring xml file. What holds a reference to the ObjectMapper is the MappingJacksonJsonView class. You then need to attach the view to a ViewResolver.

Something like this should work:

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
      <property name="mediaTypes">
      <map>
        <entry key="json" value="application/json" />
        <entry key="html" value="text/html" />
      </map>
    </property>
    <property name="viewResolvers">
      <list>
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
          <property name="prefix" value="/WEB-INF/jsp/" />
          <property name="suffix" value=".jsp" />
        </bean>
      </list>
    </property>
    <property name="defaultViews">
      <list>
        <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView">
          <property name="prefixJson" value="false" />
          <property name="objectMapper" value="customObjectMapper" />
        </bean>
      </list>
    </property>
  </bean>

Where customObjectMapper is defined elsewhere in the xml file. Note that you can directly set Spring property values with the Enums Jackson defines; see this question.

Also, ContentNegotiatingViewResolver probably isn't required, it's just the code I am using in an existing project.

Doesn't answer the question but this is the top google result.

If anybody comes here and wants do do it for Spring 4 (as it happened to me), you can use the annotation

@JsonInclude(Include.NON_NULL)

on the returning class.

I needeed to solve very similar problem, which is configuring Jackson Mapper to "Do not serialize null values for Christ's sake!!!".

I didn't want to leave fancy mvc:annotation-driven tag, so I found, how to configure Jackson's ObjectMapper without removing mvc:annotation-driven and adding not really fancy ContentNegotiatingViewResolver.

The beautiful thing is that you don't have to write any Java code yourself!

And here is the XML configuration (don't be confused with different namespaces of Jackson classes, I simply used new Jakson 2.x library ... the same should also work with Jackson 1.x libraries):

<mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <bean class="com.fasterxml.jackson.databind.ObjectMapper">
                    <property name="serializationInclusion">
                        <value type="com.fasterxml.jackson.annotation.JsonInclude.Include">NON_NULL</value>
                    </property>
                </bean>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

In spring3.2, new solution is introduced by: http://static.springsource.org/spring/docs/3.2.0.BUILD-SNAPSHOT/api/org/springframework/http/converter/json/Jackson2ObjectMapperFactoryBean.html , the below is my example:

 <mvc:annotation-driven>
   ?<mvc:message-converters>
     ??<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
       ???<property name="objectMapper">
         ????<bean
 class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
           ?????<property name="featuresToEnable">
             ??????<array>
               ???????<util:constant static-field="com.fasterxml.jackson.core.JsonParser.Feature.ALLOW_SINGLE_QUOTES" />
             ??????</array>
           ?????</property>
         ????</bean>
       ???</property>
     ??</bean>
   ?</mvc:message-converters>
 </mvc:annotation-driven>