Question

I would like to replace the default objectMapper of the MappingJacksonHttpMessageConverter.

I found a working solution but I am not happy about it:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:util="http://www.springframework.org/schema/util"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
                       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                       http://www.springframework.org/schema/context
                       http://www.springframework.org/schema/context/spring-context-3.1.xsd
                       http://www.springframework.org/schema/util
                       http://www.springframework.org/schema/util/spring-util-2.0.xsd">

<!-- Scans the classpath of this application for @Components to deploy as beans -->
<context:component-scan base-package="org.mypackage.service"/>

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
    <property name="messageConverters">
        <list>
            <!--Adding the default message converters-->
            <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="writeAcceptCharset" value="false"/>
            </bean>
            <bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter"/>

            <!--Adding our custom JSON converter-->
            <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
                <property name="objectMapper">
                    <util:constant static-field="org.mypackage.JsonUtils.MAPPER"/>
                </property>
            </bean>
        </list>
    </property>
</bean>

The solution initializes RequestMappingHandlerAdapter classes with my custom list of message converters.

I don’t like this solution because I needed to add the default message converters (which I copied from the org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter constructor).

Without adding the default converters – my controllers could handle only application/json requests and forgot how to handle other basic requests such as application/xml.

Thanks.

Answer 1

You can do it through code, without having to declare the RequestMappingHandlerAdapter bean and manually initialize all of those converters. You should write a BeanPostProcessor, like so:

public class MyBeanPostProcessor implements BeanPostProcessor {

    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }

    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof AnnotationMethodHandlerAdapter) {
            AnnotationMethodHandlerAdapter adapter = (AnnotationMethodHandlerAdapter) bean;
            HttpMessageConverter<?>[] converters = adapter.getMessageConverters();

            for (HttpMessageConverter<?> converter : converters) {
                if (converter instanceof MappingJacksonHttpMessageConverter) {
                    initConverter((MappingJacksonHttpMessageConverter) converter);
                }
            }
        } else  if(bean instanceof MappingJacksonHttpMessageConverter){
            initConverter((MappingJacksonHttpMessageConverter) bean);
        }
        return bean;
    }

    private void initConverter(MappingJacksonHttpMessageConverter converter) {
            MappingJacksonHttpMessageConverter jsonConverter = (MappingJacksonHttpMessageConverter) converter;
            final ObjectMapper mapper = // get your mapper from wherever
            jsonConverter.setObjectMapper(mapper);

            /* here you can apply any other configuration you wish*/
     }
}

And define it as a bean:

<bean class="my.package.MyBeanPostProcessor" id="myBeanPostProcessor" lazy-init="false"/>

This way you edit exactly what actually interests you – the MappingJacksonHttpMessageConverter.