OnDemandJsonPrettyPrintingFilter.java

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.jaxrs.cfg.EndpointConfigBase;
import com.fasterxml.jackson.jaxrs.cfg.ObjectWriterInjector;
import com.fasterxml.jackson.jaxrs.cfg.ObjectWriterModifier;

import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerResponseContext;
import javax.ws.rs.container.ContainerResponseFilter;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;

@Provider
public class OnDemandJsonPrettyPrintingFilter implements ContainerResponseFilter {
    public static String X_COMPANY_PRETTY_PRINT = "X-Company-Pretty-Print";
    public static String PRETTY_PRINT = "pretty-print";
    
    @Override
    public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) {
        if ("true".equalsIgnoreCase(requestContext.getUriInfo()
                                                  .getQueryParameters()
                                                  .getFirst(PRETTY_PRINT))
            || "true".equalsIgnoreCase(requestContext.getHeaders().getFirst(X_COMPANY_PRETTY_PRINT))) {
            ObjectWriterInjector.set(IndentingModifier.INSTANCE);
        }
    }

    private static class IndentingModifier extends ObjectWriterModifier {
        private static ObjectWriterModifier INSTANCE = new IndentingModifier();

        @Override
        public ObjectWriter modify(EndpointConfigBase<?> endpointConfigBase,
                                   MultivaluedMap<String, Object> multivaluedMap,
                                   Object valueToWrite,
                                   ObjectWriter objectWriter,
                                   JsonGenerator jsonGenerator) {
            jsonGenerator.useDefaultPrettyPrinter();
            return objectWriter;
        }
    }
}