Java中如何获取当前时刻的年、月、日、时、分、秒、毫秒？

如何在Java中获取当前时刻的年、月、日、时、分、秒和毫秒？我想让他们成为Strings.

您可以使用以下的吸气剂java.time.LocalDateTime为了那个原因。

LocalDateTime now = LocalDateTime.now();
int year = now.getYear();
int month = now.getMonthValue();
int day = now.getDayOfMonth();
int hour = now.getHour();
int minute = now.getMinute();
int second = now.getSecond();
int millis = now.get(ChronoField.MILLI_OF_SECOND); // Note: no direct getter available.

System.out.printf("%d-%02d-%02d %02d:%02d:%02d.%03d", year, month, day, hour, minute, second, millis);

或者，当您尚未使用 Java 8 时，请使用java.util.Calendar.

Calendar now = Calendar.getInstance();
int year = now.get(Calendar.YEAR);
int month = now.get(Calendar.MONTH) + 1; // Note: zero based!
int day = now.get(Calendar.DAY_OF_MONTH);
int hour = now.get(Calendar.HOUR_OF_DAY);
int minute = now.get(Calendar.MINUTE);
int second = now.get(Calendar.SECOND);
int millis = now.get(Calendar.MILLISECOND);

System.out.printf("%d-%02d-%02d %02d:%02d:%02d.%03d", year, month, day, hour, minute, second, millis);

无论哪种方式，现在都会打印：

2010-04-16 15:15:17.816
  

要转换一个int to String，利用String#valueOf().

如果你的意图是毕竟以人类友好的字符串格式排列和显示它们，那么最好使用 Java8java.time.format.DateTimeFormatter (教程在这里),

LocalDateTime now = LocalDateTime.now();
String format1 = now.format(DateTimeFormatter.ISO_DATE_TIME);
String format2 = now.atZone(ZoneId.of("GMT")).format(DateTimeFormatter.RFC_1123_DATE_TIME);
String format3 = now.format(DateTimeFormatter.ofPattern("yyyyMMddHHmmss", Locale.ENGLISH));

System.out.println(format1);
System.out.println(format2);
System.out.println(format3);

或者当您还没有使用 Java 8 时，请使用java.text.SimpleDateFormat:

Date now = new Date(); // java.util.Date, NOT java.sql.Date or java.sql.Timestamp!
String format1 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS", Locale.ENGLISH).format(now);
String format2 = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z", Locale.ENGLISH).format(now);
String format3 = new SimpleDateFormat("yyyyMMddHHmmss", Locale.ENGLISH).format(now);

System.out.println(format1);
System.out.println(format2);
System.out.println(format3);

无论哪种方式，这都会产生：

2010-04-16T15:15:17.816
Fri, 16 Apr 2010 15:15:17 GMT
20100416151517
  

也可以看看：

• Java 字符串到日期的转换