How to serialize Joda DateTime with Jackson JSON processor?

Question

This has become very easy with Jackson 2.0 and the Joda module.

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JodaModule());

Maven dependency:

<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-joda</artifactId>
  <version>2.1.1</version>
</dependency>  

Code and documentation: https://github.com/FasterXML/jackson-datatype-joda

Binaries: http://repo1.maven.org/maven2/com/fasterxml/jackson/datatype/jackson-datatype-joda/

In the object you're mapping:

@JsonSerialize(using = CustomDateSerializer.class)
public DateTime getDate() { ... }

In CustomDateSerializer:

public class CustomDateSerializer extends JsonSerializer<DateTime> {

    private static DateTimeFormatter formatter = 
        DateTimeFormat.forPattern("dd-MM-yyyy");

    @Override
    public void serialize(DateTime value, JsonGenerator gen, 
                          SerializerProvider arg2)
        throws IOException, JsonProcessingException {

        gen.writeString(formatter.print(value));
    }
}

As @Kimble has said, with Jackson 2, using the default formatting is very easy; simply register JodaModule on your ObjectMapper.

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JodaModule());

For custom serialization/de-serialization of DateTime, you need to implement your own StdScalarSerializer and StdScalarDeserializer; it's pretty convoluted, but anyway.

For example, here's a DateTime serializer that uses the ISODateFormat with the UTC time zone:

public class DateTimeSerializer extends StdScalarSerializer<DateTime> {

    public DateTimeSerializer() {
        super(DateTime.class);
    }

    @Override
    public void serialize(DateTime dateTime,
                          JsonGenerator jsonGenerator,
                          SerializerProvider provider) throws IOException, JsonGenerationException {
        String dateTimeAsString = ISODateTimeFormat.withZoneUTC().print(dateTime);
        jsonGenerator.writeString(dateTimeAsString);
    }
}

And the corresponding de-serializer:

public class DateTimeDesrializer extends StdScalarDeserializer<DateTime> {

    public DateTimeDesrializer() {
        super(DateTime.class);
    }

    @Override
    public DateTime deserialize(JsonParser jsonParser,
                                DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
        try {
            JsonToken currentToken = jsonParser.getCurrentToken();
            if (currentToken == JsonToken.VALUE_STRING) {
                String dateTimeAsString = jsonParser.getText().trim();
                return ISODateTimeFormat.withZoneUTC().parseDateTime(dateTimeAsString);
            }
        } finally {
            throw deserializationContext.mappingException(getValueClass());
        }
    }

Then tie these together with a module:

public class DateTimeModule extends SimpleModule {

    public DateTimeModule() {
        super();
        addSerializer(DateTime.class, new DateTimeSerializer());
        addDeserializer(DateTime.class, new DateTimeDeserializer());
    }
}

Then register the module on your ObjectMapper:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new DateTimeModule());

The easy solution

I have encountered similar problem and my solution is much clear than above.

I simply used the pattern in @JsonFormat annotation

Basically my class has a DateTime field, so I put an annotation around the getter:

@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
public DateTime getDate() {
    return date;
}

I serialize the class with ObjectMapper

    ObjectMapper mapper = new ObjectMapper();
    mapper.registerModule(new JodaModule());
    mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
    ObjectWriter ow = mapper.writer();
    try {
        String logStr = ow.writeValueAsString(log);
        outLogger.info(logStr);
    } catch (IOException e) {
        logger.warn("JSON mapping exception", e);
    }

We use Jackson 2.5.4

https://stackoverflow.com/a/10835114/1113510

Although you can put an annotation for each date field, is better to do a global configuration for your object mapper. If you use jackson you can configure your spring as follow:

<bean id="jacksonObjectMapper" class="com.company.CustomObjectMapper" />

<bean id="jacksonSerializationConfig" class="org.codehaus.jackson.map.SerializationConfig"
    factory-bean="jacksonObjectMapper" factory-method="getSerializationConfig" >
</bean>

For CustomObjectMapper:

public class CustomObjectMapper extends ObjectMapper {

    public CustomObjectMapper() {
        super();
        configure(Feature.WRITE_DATES_AS_TIMESTAMPS, false);
        setDateFormat(new SimpleDateFormat("EEE MMM dd yyyy HH:mm:ss 'GMT'ZZZ (z)"));
    }
}

Of course, SimpleDateFormat can use any format you need.

Meanwhile Jackson registers the Joda module automatically when the JodaModule is in classpath. I just added jackson-datatype-joda to Maven and it worked instantly.

<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-joda</artifactId>
  <version>2.8.7</version>
</dependency>

JSON output:

{"created" : "2017-03-28T05:59:27.258Z"}