保存到MySQL数据库时如何阻止LocalDate更改 [英] How to stop LocalDate from changing when being saved to a mySQL database

问题描述

使用JPA CriteriaBuilder API将LocalDate字段(例如'2017-09-27')保存到mySQL Date列时，结果会有所不同(例如'2017-09-26').

When saving a LocalDate field (e.g. '2017-09-27') to a mySQL Date column using JPA CriteriaBuilder API, the result is different (e.g. '2017-09-26').

我已验证使用SELECT TIMEDIFF(NOW(), UTC_TIMESTAMP)将数据库的时区设置为UTC，因为结果为'00:00:00'.

I have validated that my database's timezone is set to UTC using SELECT TIMEDIFF(NOW(), UTC_TIMESTAMP) as the result is '00:00:00'.

我正在本地进行测试，我的时区是格林尼治标准时间+ 2，所以我怀疑当从LocalDate转换为Date时，会扣除2个小时并在日期前1天产生一个日期请求的日期(假设LocalDate字段由于没有没有时间信息而被视为00:00:00.

I am testing this locally, and I have a timezone of GMT + 2, so my suspicion is that when the conversion occurs from LocalDate to Date, 2 hours are being deducted and producing a date 1 day before the requested date (assuming that the LocalDate field, as a result of it having no time information, is being treated as 00:00:00.

在这种情况下保存LocalDates的最佳方法是什么?我应该在这里 https://stackoverflow.com/a/29751575/3832047 遵循建议，并显式设置所有LocalDate字段到UTC或类似的东西?

What is the best way to save LocalDates in this situation? Should I be following the advice here https://stackoverflow.com/a/29751575/3832047 and explicitly setting all LocalDate fields to UTC or something similar?

我进行了一项测试，以查看将其转换为代码时会发生什么，并得到以下结果:

I ran a test to see what happens when converting them in code and got the following result:

Date convertedDate = Date.valueOf(localDate);

转换结果

编辑

这是我用来检索数据的代码示例，其中也发生了奇数日期更改.如果我请求2017-06-27的数据，我将收到2017-06-26的结果.

Here is an example of the code I use to retrieve the data, where the odd date change occurs as well. If I request data for 2017-06-27, I receive results for 2017-06-26.

CriteriaBuilder criteriaBuilder = sessionFactory.getCriteriaBuilder();
CriteriaQuery criteriaQuery = criteriaBuilder.createQuery(HorseAndTrailerRequest.class);
Root<HorseAndTrailerRequest> criteria = criteriaQuery.from(HorseAndTrailerRequest.class);

ParameterExpression<LocalDate> effectiveDateParameter = criteriaBuilder.parameter(LocalDate.class);
    criteriaQuery.select(criteria)
            .where(
                    criteriaBuilder.equal(criteria.get("effectiveDate"), effectiveDateParameter)
            );

TypedQuery<HorseAndTrailerRequest> query = sessionFactory.getCurrentSession().createQuery(criteriaQuery);
query.setParameter(effectiveDateParameter, date);
return query.getResultList();

推荐答案

由于LocalDate没有TimeZone，因此可以在数据库模式中将column_date映射为long，然后使用AttributeConverter将LocalDate转换为long避免时区转换问题:

Since LocalDate has no TimeZone, you can map the column_date as long in your database schema, and use AttributeConverter to convert LocalDate to long to avoid time zone conversion problems :

import javax.persistence.Converter;
import java.time.LocalDate;
import javax.persistence.AttributeConverter;
@Converter
public class LocalDateToLong implements AttributeConverter<LocalDate, Long> {

    @Override
    public Long convertToDatabaseColumn(LocalDate date) {
        if (date != null) {
            long epochDay = date.toEpochDay();
            return epochDay;
        }
        return null;
    }

    @Override
    public LocalDate convertToEntityAttribute(Long epochDay) {
        // TODO Auto-generated method stub
        if (epochDay != null) {
            LocalDate date = LocalDate.ofEpochDay(epochDay);
            return date;
        }
        return null;
    }

}

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