Jackson , java.time , ISO 8601 , serialize without milliseconds
Solution 1
Update:
Just add a @JsonFormat
annotation with the date format above the Instant
property. It's very easy.
In the case you have an ObjectMapper with the JavaTimeModule
like next:
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
If you have a class with an Instant
property, you should add the @JsonFormat
annotation and put the date pattern which hasn't milliseconds. It would be like next:
public static class TestDate {
@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss", timezone = "UTC")
Instant instant;
//getters & setters
}
So if you serialize an object to Json it works perfectly:
String json = mapper.writeValueAsString(testDate);
System.out.println(json);
Output
{"instant":"2016-11-10 06:03:06"}
Old Answer. I don't know why but It doesn't work properly:
You could use the Jackson2ObjectMapperBuilder
to build it.
You just need to add the dateFormat you want. It would be something like next:
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
ObjectMapper mapper = Jackson2ObjectMapperBuilder
.json()
.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
.modules(new JavaTimeModule())
.dateFormat(dateFormat)
.build();
Solution 2
Here is an alternative which is something you can set globally, but will need you to use ZonedDateTime
with instant formatter as we can't set the format for the Instant
Serializer provided with Java Time Module.
You wont see any side effects of using zoned date time for instant as jackson serializes the zone id separately and is disabled by default. So technically, this is similar to applying the formatter to Instant
.
When used this way, the ZonedDateTime
serializer delegates the serialization to InstantBaseSerializer
and uses the specified custom format.
@RunWith(JUnit4.class)
public class InstantNoMillisTest {
private ObjectMapper objectMapper;
@Before
public void init() {
JavaTimeModule module = new JavaTimeModule();
ZonedDateTimeSerializer zonedDateTimeSerializer = new ZonedDateTimeSerializer(new DateTimeFormatterBuilder().appendInstant(0).toFormatter());
module.addSerializer(ZonedDateTime.class, zonedDateTimeSerializer);
module.addDeserializer(ZonedDateTime.class, InstantDeserializer.ZONED_DATE_TIME);
objectMapper = Jackson2ObjectMapperBuilder.json()
.modules(module)
.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
.build();
}
@Test
public void serialize() throws IOException {
ZonedDateTime zonedDateTime = ZonedDateTime.now();
String noMillis = objectMapper.writeValueAsString(zonedDateTime);
System.out.print(noMillis);
}
@Test
public void deserialize() throws IOException {
String dateTime = "\"2017-10-26T12:54:59Z\"";
ZonedDateTime noMillis = objectMapper.readValue(dateTime, ZonedDateTime.class);
System.out.print(noMillis);
}
}
Solution 3
Here's some Kotlin code of formatting Instant
fields, so they will not contain milliseconds, you can use custom date formatters
ObjectMapper().apply {
val javaTimeModule = JavaTimeModule()
javaTimeModule.addSerializer(Instant::class.java, Iso8601WithoutMillisInstantSerializer())
registerModule(javaTimeModule)
disable(WRITE_DATES_AS_TIMESTAMPS)
}
private class Iso8601WithoutMillisInstantSerializer
: InstantSerializer(InstantSerializer.INSTANCE, false, DateTimeFormatterBuilder().appendInstant(0).toFormatter())
Benjamin M
Updated on June 13, 2022Comments
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Benjamin M almost 2 years
I'm using Jackson 2.8 and need to communicate with an API that doesn't allow milliseconds within ISO 8601 timestamps.
The expected format is this:
"2016-12-24T00:00:00Z"
I'm using Jackson's JavaTimeModule with
WRITE_DATES_AS_TIMESTAMPS
set tofalse
.But this will print milliseconds.
So I tried to use
objectMapper.setDateFormat
which didn't change anything.My current workaround is this:
ObjectMapper om = new ObjectMapper(); DateTimeFormatter dtf = new DateTimeFormatterBuilder() .appendInstant(0) .toFormatter(); JavaTimeModule jtm = new JavaTimeModule(); jtm.addSerializer(Instant.class, new JsonSerializer<Instant>() { @Override public void serialize(Instant value, JsonGenerator gen, SerializerProvider serializers) throws IOException, JsonProcessingException { gen.writeString(dtf.format(value)); } }); om.registerModule(jtm);
I'm overriding the default serializer for
Instant.class
which works.
Is there any nice way using some configuration parameter to solve this?
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Benjamin M over 7 yearsCopy & Pasted your code. It doesn't work. Still get date + time + milliseconds. :(
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Benjamin M over 7 yearsThank you. But this way I have to annotate all and every Instant field.. I'd like to set that format globally within the ObjectMapper.
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Whimusical over 6 yearsThat makes it very difficult to deserialize, as there is no analogous way to do the hack in reverse
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s7vr over 6 years@Whimusical Updated answer to include the deserialize test case.
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Whimusical over 6 yearsDoes instantdeserializer work here? Really interesting
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RobertG over 5 yearsIt should be "yyyy-MM-dd HH:mm:ss" for a 24-hour format to avoid confusion (a.m. and p.m. are not part of this output)
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broc.seib almost 4 yearsExcellent answer.