How Can I Format LocalDate with Jackson in Java 8?

Formatting LocalDate with Jackson in Java 8

When dealing with java.util.Date, the @JsonFormat annotation provides convenient formatting. However, for Java 8's LocalDate field, using custom serializers and deserializers may not suffice.

To achieve the desired formatting, a more comprehensive approach is recommended. By introducing the Jackson JSR310Module, additional functionalities become available.

Dependency

First, add the Jackson dependency:

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.4.0</version>
</dependency>

Note: Ensure that the included dependency versions are aligned to avoid potential class resolution conflicts.

ContextResolver

Next, define a ContextResolver for ObjectMapper:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import javax.ws.rs.ext.ContextResolver;
import javax.ws.rs.ext.Provider;

@Provider
public class ObjectMapperContextResolver implements ContextResolver<ObjectMapper> {  
    private final ObjectMapper MAPPER;

    public ObjectMapperContextResolver() {
        MAPPER = new ObjectMapper();
        MAPPER.registerModule(new JavaTimeModule());
        MAPPER.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return MAPPER;
    }  
}

Resource Class

In the resource class, utilize the ObjectMapperContextResolver:

@Path("person")
public class LocalDateResource {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response getPerson() {
        Person person = new Person();
        person.birthDate = LocalDate.now();
        return Response.ok(person).build();
    }

    @POST
    @Consumes(MediaType.APPLICATION_JSON)
    public Response createPerson(Person person) {
        return Response.ok(
                DateTimeFormatter.ISO_DATE.format(person.birthDate)).build();
    }

    public static class Person {
        public LocalDate birthDate;
    }
}

Example

Request:

curl -v http://localhost:8080/api/person

Result:

{"birthDate":"2015-03-01"}

Post Request:

curl -v -POST -H "Content-Type:application/json" -d "{\"birthDate\":\"2015-03-01\"}" http://localhost:8080/api/person

Post Result:

2015-03-01

Conclusion

By employing JSR310Module, ObjectMapperContextResolver, and setting SerializationFeature.WRITE_DATES_AS_TIMESTAMPS to false, Java 8's LocalDate can be formatted effectively with Jackson.

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