Gists for JsonSnakeCase Annotation (From Dropwizard)

AnnotationSensitivePropertyNamingStrategy.java

package com.yammer.dropwizard.json;

import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.introspect.AnnotatedField;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
import com.fasterxml.jackson.databind.introspect.AnnotatedParameter;

/**
 * A {@link PropertyNamingStrategy} implementation which, if the declaring class of a property is
 * annotated with {@link JsonSnakeCase}, uses a {@link LowerCaseWithUnderscoresStrategy}, and uses
 * the default {@link PropertyNamingStrategy} otherwise.
 */
public class AnnotationSensitivePropertyNamingStrategy extends PropertyNamingStrategy {
    private static final long serialVersionUID = -1372862028366311230L;

    private final LowerCaseWithUnderscoresStrategy snakeCase;

    public AnnotationSensitivePropertyNamingStrategy() {
        super();
        this.snakeCase = new LowerCaseWithUnderscoresStrategy();
    }

    @Override
    public String nameForConstructorParameter(MapperConfig<?> config,
                                              AnnotatedParameter ctorParam,
                                              String defaultName) {
        if (ctorParam.getDeclaringClass().isAnnotationPresent(JsonSnakeCase.class)) {
            return snakeCase.nameForConstructorParameter(config, ctorParam, defaultName);
        }
        return super.nameForConstructorParameter(config, ctorParam, defaultName);
    }

    @Override
    public String nameForField(MapperConfig<?> config,
                               AnnotatedField field,
                               String defaultName) {
        if (field.getDeclaringClass().isAnnotationPresent(JsonSnakeCase.class)) {
            return snakeCase.nameForField(config, field, defaultName);
        }

        return super.nameForField(config, field, defaultName);
    }

    @Override
    public String nameForGetterMethod(MapperConfig<?> config,
                                      AnnotatedMethod method,
                                      String defaultName) {
        if (method.getDeclaringClass().isAnnotationPresent(JsonSnakeCase.class)) {
            return snakeCase.nameForGetterMethod(config, method, defaultName);
        }
        return super.nameForGetterMethod(config, method, defaultName);
    }

    @Override
    public String nameForSetterMethod(MapperConfig<?> config,
                                      AnnotatedMethod method,
                                      String defaultName) {
        if (method.getDeclaringClass().isAnnotationPresent(JsonSnakeCase.class)) {
            return snakeCase.nameForSetterMethod(config, method, defaultName);
        }
        return super.nameForSetterMethod(config, method, defaultName);
    }
}

JsonSnakeCase.java

package com.yammer.dropwizard.json;

import com.fasterxml.jackson.annotation.JacksonAnnotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Marker annotation which indicates that the annotated case class should be
 * serialized and deserialized using {@code snake_case} JSON field names instead
 * of {@code camelCase} field names.
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotation
public @interface JsonSnakeCase {

}

USAGE

    private static ObjectMapper configure(ObjectMapper mapper) {
        mapper.registerModule(new GuavaModule());
        mapper.registerModule(new LogbackModule());
        mapper.registerModule(new GuavaExtrasModule());
        mapper.registerModule(new JodaModule());
        mapper.registerModule(new AfterburnerModule());
        mapper.registerModule(new FuzzyEnumModule());
        mapper.registerModule(new Jdk7Module());
        mapper.setPropertyNamingStrategy(new AnnotationSensitivePropertyNamingStrategy());
        mapper.setSubtypeResolver(new DiscoverableSubtypeResolver());

        return mapper;
    }