java8中时间的各种转换(LocalDateTime)

注意：LocalDateTime是带时分秒的

1.将LocalDateTime转为自定义的时间格式的字符串

public static String getDateTimeAsString(LocalDateTime localDateTime, String format) {
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern(format);
    return localDateTime.format(formatter);
}

2.将long类型的timestamp转为LocalDateTime

public static LocalDateTime getDateTimeOfTimestamp(long timestamp) {
    Instant instant = Instant.ofEpochMilli(timestamp);
    ZoneId zone = ZoneId.systemDefault();
    return LocalDateTime.ofInstant(instant, zone);
}

3.将LocalDateTime转为long类型的timestamp

public static long getTimestampOfDateTime(LocalDateTime localDateTime) {
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDateTime.atZone(zone).toInstant();
    return instant.toEpochMilli();
}

4.将某时间字符串转为自定义时间格式的LocalDateTime

public static LocalDateTime parseStringToDateTime(String time, String format) {
    DateTimeFormatter df = DateTimeFormatter.ofPattern(format);
    return LocalDateTime.parse(time, df);
}