Java:日历实例的时间错误？

Question

运行:

public class test {
    @Test
    public void displayDate() {
        SimpleDateFormat MONTH_FORMAT = new SimpleDateFormat("MMM", Locale.getDefault());
        String testDateStr = "2017-07-01T07:58:23.000Z";
        Calendar calendar = getFormatedDate(testDateStr);
        int yearInt  = calendar.get(Calendar.YEAR);
        String monthStr = MONTH_FORMAT.format(calendar.getTime()).toUpperCase();
        int monthInt = calendar.get(Calendar.MONTH);
        int dayInt  = calendar.get(Calendar.DAY_OF_MONTH);
        int hour24 = calendar.get(Calendar.HOUR_OF_DAY);
        int min = calendar.get(Calendar.MINUTE);
        int sec = calendar.get(Calendar.SECOND);
        System.out.println(testDateStr);
        System.out.println(String.format("%s-%s-%s %s:%s:%s", yearInt, monthStr, dayInt, hour24, min, sec));
        System.out.println(String.format("%s-%s-%s %s:%s:%s", yearInt, monthInt, dayInt, hour24, min, sec));

    }

    private Calendar getFormatedDate(String dateStr) {
        Instant instant;
        try {
            instant = Instant.parse(dateStr);
        } catch (DateTimeParseException e) {
            e.printStackTrace();
            return null;
        }
        ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.systemDefault());
        Calendar calendar = GregorianCalendar.from(zdt);
        return calendar;
    }
}

我得到:

2017-07-01T07:58:23.000Z
2017-JUL-1 9:58:23
2017-6-1 9:58:23

请注意，我得到的小时 = 9，而预期为 7

问题

1. 为什么会出现这样的结果
2. 如何获得正确的结果？

谢谢!

Answer 1

Why this result

由于这一行:ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.systemDefault());
您将您的时区强制设置为dateStr中定义的时区，因此日历将使用您的时区而不是原始时区。

How to get the right result ?

将您的 getFormatedDate 方法更改为:

private Calendar getFormatedDate(final String dateStr) {
    final ZonedDateTime zdt = ZonedDateTime.parse(dateStr);
    return GregorianCalendar.from(zdt);
}