Serialize Date in a JSON REST web service as ISO-8601 string

Question

I have a JAX-RS application using JBoss AS 7.1, and I POST/GET JSON and XML objects which include Dates (java.util.Date):

@XmlRootElement
@XmlAccessorType(XmlAccessField.FIELD)
public class MyObject implements Serializable
{
    @XmlSchemaType(name = "dateTime")
    private Date date;
    ...
}

When I use @Produce("application/xml") on the get method, the objets are serialized as XML and the dates are converted into ISO-8601 strings (e.g. "2012-12-10T14:50:12.123+02:00").

However, if I use @Produce("application/json") on the get method, the dates in the JSON objects are timestamps (e.g. "1355147452530") instead of ISO-8601 strings.

How can I do to configure the JAX-RS implementation (RESTEasy) to serialize dates in JSON format as ISO-8601 strings instead of timestamps ?

Thank you for your answers.

Note: I also tried to use a custom JAX-RS provider to do the JSON serialization for Dates

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class CustomJsonDateProvider implements MessageBodyWriter<Date>
{
    ...
}

This provider seems to be registered by RESTeasy on JBoss startup:

[org.jboss.jaxrs] Adding JAX-RS provider classes: package.CustomJsonDateProvider
...
[org.jboss.resteasy.cdi.CdiInjectorFactory] No CDI beans found for class package.CustomJsonDateProvider. Using default ConstructorInjector.

but it is never used !

Answer 1

I assume your json parser is Jackson, try:

@JsonFormat(shape=JsonFormat.Shape.STRING, pattern="yyyy-MM-dd,HH:00", timezone="CET")
public Date date;

(since Jackson 2.0)

Answer 2

The default JBoss parser is Jettison, but I wasn't able to change the date format. So I switched to Jackson and added the following class to my project to configure it:

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class JacksonConfig implements ContextResolver<ObjectMapper>
{
    private final ObjectMapper objectMapper;

    public JacksonConfig()
    {
        objectMapper = new ObjectMapper();
        objectMapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESPAMPS, false);
    }

    @Override
    public ObjectMapper getContext(Class<?> objectType)
    {
        return objectMapper;
    }
}

Answer 3

Sorry people for yelling out loud - I found the answers here

http://wiki.fasterxml.com/JacksonFAQDateHandling,

here

http://wiki.fasterxml.com/JacksonFAQ#Serializing_Dates,

here

http://wiki.fasterxml.com/JacksonHowToCustomSerializers

here

http://jackson.codehaus.org/1.1.2/javadoc/org/codehaus/jackson/map/util/StdDateFormat.html

Using the @JsonSerialize(using= ... ) way:

public class JsonStdDateSerializer
extends JsonSerializer<Date> {

  private static final DateFormat iso8601Format =
    StdDateFormat.getBlueprintISO8601Format();

  @Override
  public void serialize(
    Date date, JsonGenerator jgen, SerializerProvider provider)
  throws IOException, JsonProcessingException {

    // clone because DateFormat is not thread-safe
    DateFormat myformat = (DateFormat) iso8601Format.clone();
    String formattedDate = myformat.format(date);
    jgen.writeString(formattedDate);
  }
}

Answer 4

Declare the same Serializer used by Soap/XML:

@XmlElement(name = "prealert_date")
@XmlSchemaType(name = "dateTime")
@JsonSerialize(using = XMLGregorianCalendarSerializer.class)
protected XMLGregorianCalendar prealertDate;