Gson Configuration

Gson configuration and serializers/deserializers for Date/Time in java.time.* package.

Dependency 🚀

Gradle

implementation "io.goodforgod:gson-configuration:2.0.0"

Maven

<dependency>
    <groupId>io.goodforgod</groupId>
    <artifactId>gson-configuration</artifactId>
    <version>2.0.0</version>
</dependency>

Serializers\Deserializers

Library include serializers & deserializers for most java.time.* datetime objects, supported list:

• Instant
• LocalDate
• LocalTime
• LocalDateTime
• OffsetTime
• OffsetDateTime
• ZonedDateTime
• Year
• YearMonth
• Month
• MonthDay
• DayOfWeek
• ZoneId
• ZoneOffset

Formatters

Gson Configuration by default comes with ISO8601 with millis precision (basically default Java ISO8601 formatters but with millis precision)

Here is list of such formatters:

• LocalDateTime - uuuu-MM-dd'T'HH:mm:ss[.SSS]
• LocalDate - uuuu-MM-dd
• LocalTime - HH:mm:ss[.SSS]
• OffsetDateTime - uuuu-MM-dd'T'HH:mm:ss[.SSS]XXX
• OffsetTime - HH:mm:ss[.SSS]XXX
• ZonedDateTime - uuuu-MM-dd'T'HH:mm:ss[.SSS]XXX['['VV']']

If you want to know more about why use such Java Date & Time formats, you can read more here

GsonConfiguration configuration = new GsonConfiguration();

Gson Configuration

Library provides configuration for configuring GsonBuilder for most properties:

GsonBuilder builder = new GsonConfiguration()
        .setDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX")
        .setInstantFormat("uuuu-MM-dd HH:mm:ss")
        .setComplexMapKeySerialization(true)
        .setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)
        .setLongSerializationPolicy(LongSerializationPolicy.STRING)
        .setLenient(true)
        .setEscapeHtmlChars(false)
        .setPrettyPrinting(true)
        .setGenerateNonExecutableJson(true)
        .setSerializeNulls(true)
        .setSerializeSpecialFloatingPointValues(true)
        .setExcludeFieldsWithoutExposeAnnotation(true)
        .setExcludeFieldsWithModifiers(GsonConfiguration.FieldModifiers.TRANSIENT)
        .builder();

You can configure DateTimeFormatters for provided adapters:

GsonBuilder builder = new GsonConfiguration()
        .setInstantFormat("uuuu-MM-dd HH:mm:ss")
        .builder();

Properties file

By default Gson or GsonBuilder that is build via GsonConfiguration or GsonFactory doesn't serialize/deserialize transient, static, volatile, synchronized fields. You need to use configuration setters to configure it otherwise.

GsonConfiguration also can be filled from properties file.

How to build GsonConfiguration from Properties:

InputStream resource = getClass().getClassLoader().getResourceAsStream("gson.properties");
Properties properties = new Properties();
properties.load(resource);

GsonConfiguration configuration = GsonConfiguration.ofProperties(properties);

Full list of properties (check GsonProperties):

gson.format.instant=uuuu-MM-dd'T'HH:mm:ssX
gson.format.localDate=uuuu-MM-dd
gson.format.localTime=HH:mm:ss.SSS
gson.format.localDateTime=uuuu-MM-dd'T'HH:mm:ss.SSS
gson.format.offsetTime=HH:mm:ss.SSSXXX
gson.format.offsetDateTime=uuuu-MM-dd'T'HH:mm:ss.SSSXXX
gson.format.zonedDateTime=uuuu-MM-dd'T'HH:mm:ss.SSSXXX
gson.format.year=uuuu
gson.format.yearMonth=uuuu-MM
gson.format.monthDay=MM-dd
gson.format.date=yyyy-MM-dd'T'HH:mm:ss.SSSXXX

gson.forceIsoChronology=true
gson.forceResolverStrict=true

gson.lenient=true
gson.serializeNulls=true
gson.prettyPrinting=true
gson.escapeHtmlChars=false
gson.generateNonExecutableJson=true
gson.serializeComplexMapKey=true
gson.serializeSpecialFloatingPointValues=true
gson.excludeFieldsWithoutExposeAnnotation=false
gson.excludeFieldsWithModifiers=TRANSIENT,STATIC,SYNCHRONIZED,VOLATILE

gson.policy.fieldNaming=UPPER_CAMEL_CASE
gson.policy.longSerialization=STRING

Factory

Gson can also be instantiated via properties using GsonFactory.

GsonFactory is looking for property file in root resource: gson.properties

Gson gson = new GsonFactory().build();

Gson Builder

All adapters already registered via when using GsonConfiguration#builder.

You can register them manually:

GsonBuilder builder = new GsonBuilder()
        .registerTypeAdapter(LocalDate.class, LocalDateSerializer.INSTANCE)

You can register with custom formatter also:

GsonBuilder builder = new GsonBuilder()
        .registerTypeAdapter(LocalDate.class, new LocalDateSerializer(DateTimeFormatters.ISO_LOCAL_DATE))

License

This project licensed under the MIT - see the LICENSE file for details.