Java 时间格式转换

public class DateUtil {

    /**
     * 生成ISO-8601 规范的时间格式
     *
     * @param date
     * @return
     */
    public static String formatiso8601Datestring(Date date) {
        String pattern = "yyyy-MM-dd'T'HH:mm:ss.SSSZ";
        return DateFormatUtils.format(date, pattern);
    }

    /***
     * 生成时间戳
     * @param s
     * @return 时间戳
     */
    public static String getTimeStamp(String s) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMdd");
        Date date = null;

        try {
            date = simpleDateFormat.parse(s);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        long ts = Objects.requireNonNull(date).getTime();
        return String.valueOf(ts);
    }

    /***
     * 返回时间戳对应的时间
     * @param s
     * @return 时间
     */
    public static Timestamp getDateFromTimeStamp(String s) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        long lt = new Long(s);
        Date date1 = new Date(lt);
        return Timestamp.valueOf(simpleDateFormat.format(date1));
    }

     * 获取反时间戳
     *
     * @return
     */
    public static Long getCurrentReverseTime() {
        long longTime = System.currentTimeMillis() * 1000000 + CalculateUtil.getNext(999999);
        return Long.MAX_VALUE - longTime;
    }

    /**
     * 获取原时间戳
     *
     * @param reverseTime
     * @return
     */
    public static Long recoverReverseTime(Long reverseTime) {
        long longTime = Long.MAX_VALUE - reverseTime;
        return longTime / 1000000;
    }

    /**
     * 生成页面普通展示时间
     *
     * @param date
     * @return
     */
    public static String formatNormalDateString(Date date) {
        String pattern = "yyyy-MM-dd HH:mm:ss";
        return DateFormatUtils.format(date, pattern);
    }

    //时间戳转化成时间
    public Date formatTime(Long time) throws ParseException {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String strTime = format.format(time);
        Date date = format.parse(strTime);
        return date;
    }

    public static void main(String[] args) {

        System.out.println(getTimeStamp("20190603"));
    }

}