1. Overview

1.概述

In this quick tutorial, we’ll discuss LocalDate and XMLGregorianCalendar and provide examples of converting between the two types.

在这个快速教程中，我们将讨论LocalDate和XMLGregorianCalendar，并提供这两种类型之间转换的例子。

2. XMLGregorianCalendar

The XML Schema standard defines clear rules for specifying dates in XML format. In order to use this format, the Java class XMLGregorianCalendar, introduced in Java 1.5, is a representation of the W3C XML Schema 1.0 date/time datatypes.

XML Schema标准定义了明确的规则来指定XML格式的日期。为了使用这种格式，Java类XMLGregorianCalendar，在Java 1.5中引入，是W3C XML Schema 1.0日期/时间数据类型的代表。

3. LocalDate

3.本地日期

A LocalDate instance represents a date without a timezone in the ISO-8601 calendar system. As a result, LocalDate is, for example, suitable for storing birthdays but not anything related to time. Java introduced LocalDate in version 1.8.

LocalDate实例表示ISO-8601日历系统中没有时区的日期。因此，例如，LocalDate适合存储生日，但不适合存储与时间有关的东西。Java在1.8版本中引入了LocalDate。

4. From LocalDate to XMLGregorianCalendar

4.从LocalDate到XMLGregorianCalendar

First, we’ll see how to convert from LocalDate to XMLGregorianCalendar. In order to generate a new instance of XMLGregorianCalendar, we use a DataTypeFactory from the javax.xml.datatype package.

首先，我们来看看如何从LocalDate转换到XMLGregorianCalendar。为了生成一个新的XMLGregorianCalendar的实例，我们使用javax.xml.datatype包中的DataTypeFactory。

So, let’s create an instance of LocalDate and convert it to XMLGregorianCalendar:

因此，让我们创建一个LocalDate的实例并将其转换为XMLGregorianCalendar。

LocalDate localDate = LocalDate.of(2019, 4, 25);

XMLGregorianCalendar xmlGregorianCalendar = 
  DatatypeFactory.newInstance().newXMLGregorianCalendar(localDate.toString());

assertThat(xmlGregorianCalendar.getYear()).isEqualTo(localDate.getYear());
assertThat(xmlGregorianCalendar.getMonth()).isEqualTo(localDate.getMonthValue());
assertThat(xmlGregorianCalendar.getDay()).isEqualTo(localDate.getDayOfMonth());
assertThat(xmlGregorianCalendar.getTimezone()).isEqualTo(DatatypeConstants.FIELD_UNDEFINED);

As previously noted, an XMLGregorianCalendar instance has the possibility of having timezone information. However, LocalDate doesn’t have any information about time.

如前所述，XMLGregorianCalendar实例有可能具有时区信息。然而，LocalDate没有任何关于时间的信息。

Therefore, when we perform the conversion, the timezone value will remain as FIELD_UNDEFINED.

因此，当我们进行转换时，时区值将保持为FIELD_UNDEFINED。

5. From XMLGregorianCalendar to LocalDate

5.从XMLGregorianCalendar到LocalDate

Likewise, we’ll now see how to perform the conversion the other way around. As it turns out, converting from a XMLGregorianCalendar to LocalDate is much easier.

同样地，我们现在将看到如何以另一种方式进行转换。事实证明，从XMLGregorianCalendar到LocalDate的转换要简单得多。

Again, since LocalDate does not have information about time, a LocalDate instance can contain only a subset of the XMLGregorianCalendar information.

同样，由于LocalDate没有时间信息，LocalDate实例只能包含XMLGregorianCalendar信息的一个子集。

Let’s create an instance of XMLGregorianCalendar and perform the conversion:

让我们创建一个XMLGregorianCalendar的实例并执行转换。

XMLGregorianCalendar xmlGregorianCalendar = 
  DatatypeFactory.newInstance().newXMLGregorianCalendar("2019-04-25");

LocalDate localDate = LocalDate.of(
  xmlGregorianCalendar.getYear(), 
  xmlGregorianCalendar.getMonth(), 
  xmlGregorianCalendar.getDay());

assertThat(localDate.getYear()).isEqualTo(xmlGregorianCalendar.getYear());
assertThat(localDate.getMonthValue()).isEqualTo(xmlGregorianCalendar.getMonth());
assertThat(localDate.getDayOfMonth()).isEqualTo(xmlGregorianCalendar.getDay());

6. Conclusion

6.结语

In this quick tutorial, we’ve covered the transformations between LocalDate instances and XMLGregorianCalendar, and vice-versa.

在这个快速教程中，我们已经介绍了LocalDate实例和XMLGregorianCalendar之间的转换，反之亦然。

And, as always, the sample code is available over on GitHub.

而且，像往常一样，样本代码可以在GitHub上找到。