Autowiring in JsonDeserializer: SpringBeanAutowiringSupport vs HandlerInstantiator

Question

I have written a custom JsonDeserializer which contains an autowired service, as follows:

public class PersonDeserializer extends JsonDeserializ         


        

Answer 1

As suggested in this comment and found on this link you need to create custom HandlerInstantiator:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;

import com.fasterxml.jackson.databind.DeserializationConfig;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.KeyDeserializer;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.cfg.HandlerInstantiator;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.introspect.Annotated;
import com.fasterxml.jackson.databind.jsontype.TypeIdResolver;
import com.fasterxml.jackson.databind.jsontype.TypeResolverBuilder;

@Component
public class SpringBeanHandlerInstantiator extends HandlerInstantiator {

    private ApplicationContext applicationContext;

    @Autowired
    public SpringBeanHandlerInstantiator(ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }

    @Override
    public JsonDeserializer deserializerInstance(DeserializationConfig config,
            Annotated annotated,
            Class deserClass) {
        try {
            return (JsonDeserializer) applicationContext.getBean(deserClass);
        } catch (Exception e) {
            // Return null and let the default behavior happen
        }
        return null;
    }

    @Override
    public KeyDeserializer keyDeserializerInstance(DeserializationConfig config,
            Annotated annotated,
            Class keyDeserClass) {
        try {
            return (KeyDeserializer) applicationContext.getBean(keyDeserClass);
        } catch (Exception e) {
            // Return null and let the default behavior happen
        }
        return null;
    }

    @Override
    public JsonSerializer serializerInstance(SerializationConfig config, Annotated annotated, Class serClass) {
        try {
            return (JsonSerializer) applicationContext.getBean(serClass);
        } catch (Exception e) {
            // Return null and let the default behavior happen
        }
        return null;
    }

    @Override
    public TypeResolverBuilder typeResolverBuilderInstance(MapperConfig config, Annotated annotated,
            Class builderClass) {
        try {
            return (TypeResolverBuilder) applicationContext.getBean(builderClass);
        } catch (Exception e) {
            // Return null and let the default behavior happen
        }
        return null;
    }

    @Override
    public TypeIdResolver typeIdResolverInstance(MapperConfig config, Annotated annotated, Class resolverClass) {
        try {
            return (TypeIdResolver) applicationContext.getBean(resolverClass);
        } catch (Exception e) {
            // Return null and let the default behavior happen
        }
        return null;
    }
}

Custom ObjectMapper:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.cfg.HandlerInstantiator;


public class CustomObjectMapper extends ObjectMapper {
    private static final long serialVersionUID = -8865944893878900100L;

    @Autowired
    ApplicationContext applicationContext;

    public JamaxObjectMapper() {
        // Problems serializing Hibernate lazily initialized collections?  Fix here.
//        HibernateModule hm = new HibernateModule();
//        hm.configure(com.fasterxml.jackson.module.hibernate.HibernateModule.Feature.FORCE_LAZY_LOADING, true);
//        this.registerModule(hm);

        // Jackson confused by what to set or by extra properties?  Fix it.
        this.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        this.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        this.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
    }

    @Override
    @Autowired
    public Object setHandlerInstantiator(HandlerInstantiator hi) {
        return super.setHandlerInstantiator(hi);
    }
}

and register your custom ObjectMapper:

At this moment you can use:

@JsonDeserialize(contentUsing=PersonDeserializer.class)
public void setPerson(Person person) {
    ...
}

... and personService will not be null.