java中将UTC时间转成本地使用时间

最新推荐文章于 2024-08-14 15:07:21 发布

原创最新推荐文章于 2024-08-14 15:07:21 发布 · 6.6k 阅读

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#java #calendar #string #date #parsing #exception

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本文介绍了一种高性能的方法，用于将特定格式的字符串转换为日期时间对象。该方法通过直接访问字符串子串来提高效率，并详细展示了如何提取年、月、日等信息并构建Calendar对象。

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/**
         * This method takes a formatted string and turns it into a calendar. This
         * approach is trimmed for performance, using high-speed substring access to
         * the string rather than dumb parsing
         *
         * @param date
         *            the String to read the date from
         * @return a calendar representing the date found in the string
         */
        private static Calendar getStringToCal(String date) {
            final String year = date.substring(0, 4);
            final String month = date.substring(5, 7);
            final String day = date.substring(8, 10);
            final String hour = date.substring(11, 13);
            final String minute = date.substring(14, 16);
            final String second = date.substring(17, 19);
            final int millisecond = Integer.valueOf(date.substring(20, 23));
            Calendar result =
                new GregorianCalendar(Integer.valueOf(year),
                    Integer.valueOf(month) - 1, Integer.valueOf(day),
                    Integer.valueOf(hour), Integer.valueOf(minute),
                    Integer.valueOf(second));
            result.set(Calendar.MILLISECOND, millisecond);
            result.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
            return result;

}

如参数是2012-06-26T08:25:49.670，

try {
                Calendar cal=getStringToCal(time);
                date = new Date(cal.getTimeInMillis());
              } catch (Exception e) {
                e = null;

              }

date为转换后的时间