How to skip jackson timezone correction in spring-mvc?

问题

I want to configure jackson to output any date/time values with the following format:

spring.jackson.date-format=yyyy-MM-dd'T'HH:mm:ss

I'm fetching many database rows and return them just as a json map.

@RestController
public class MyService {
    @GetMapping
    public List<Map<String, Object>> get(Param params) {
             return jdbcTemplate.queryForList(sql, params);
    }
}

Problem: the databases and jvm default timezone is Europe/Berlin, thus UTC+2. Therefor jackson automatically converts any database-received java.sql.Timestamp to UTC first (subtracts 2 hours), and then outputs them via json.

In the mysql database itself, it's a datetime type.

But I just want jackson to output the timestamps "as is", without prior conversion! Is that possible to skip timezone correction?

I just want to ignore the timezone without conversation. Just cut it.

回答1:

Approach #1: Setting a default time zone

You could set a time zone in the date format used by ObjectMapper. It will be used for Date and subclasses:

DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
dateFormat.setTimeZone(TimeZone.getTimeZone("Europe/Berlin"));

ObjectMapper mapper = new ObjectMapper();
mapper.setDateFormat(dateFormat);

In Spring applications, to configure ObjectMapper, you can do as follows:

@Bean
public ObjectMapper objectMapper() {

    DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
    dateFormat.setTimeZone(TimeZone.getTimeZone("Europe/Berlin"));

    ObjectMapper mapper = new ObjectMapper();
    mapper.setDateFormat(dateFormat);
    return mapper;
}

In Spring Boot you can use the property spring.jackson.time-zone to define the timezone:

spring.jackson.time-zone: Europe/Berlin

For more details on the common application properties, refer to the documentation.

Approach #2: Using the Java 8 Date and Time API

Instead of using Timestamp, you could consider LocaDateTime from the JSR-310. It was introduced in Java 8. The "local" date and time classes (LocalDateTime, LocalDate and LocalTime) are not tied to any one locality or time zone. From the LocalDateTime documentation:

This class does not store or represent a time-zone. Instead, it is a description of the date, as used for birthdays, combined with the local time as seen on a wall clock. It cannot represent an instant on the time-line without additional information such as an offset or time-zone.

This answer will give you more details on the new date and time classes.

Jackson has a module that supports JSR-310 types. Add it to your dependencies:

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.9</version>
</dependency>

Then register the JavaTimeModule module in your ObjectMapper instance:

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);

Most JSR-310 types will be serialized using a standard ISO-8601 string representation. If you need a custom format, you can use your own serializer and deserializer implementation. See the documentation for details.

回答2:

Finally it turned out the simples way is to just set the jacksons ObjectMapper (which uses UTC by defaut) timezone to the jvm defaults:

@Bean
public Jackson2ObjectMapperBuilderCustomizer init() {
    return new Jackson2ObjectMapperBuilderCustomizer() {
        @Override
        public void customize(Jackson2ObjectMapperBuilder builder) {
            builder.timeZone(TimeZone.getDefault());
        }
    };
}

I'd appreciate if anybody knows how I can achieve the same by just using the spring.jackson.time-zone application.property.

来源：https://stackoverflow.com/questions/50045912/how-to-skip-jackson-timezone-correction-in-spring-mvc

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