Java中常用时间的一些相关方法

public static void main(String[] args) {

     //Date

     Date now = new Date();

     System.out.println(now);

     //java8的时间

     LocalDateTime localDateTime = LocalDateTime.now();

     System.out.println(localDateTime);

     Calendar calendar = Calendar.getInstance();

     Date time = calendar.getTime();

     System.out.println(time);

     System.out.println( "年" + calendar.get(Calendar.YEAR));

     System.out.println( "月" + (calendar.get(Calendar.MONTH) + 1 ));

     //joda time

     DateTime dateTime = DateTime.now();

     System.out.println(dateTime);

}

public static void main(String[] args) {

     //建议使用Calendar  可以设置年月日时分秒

     Calendar calendar = Calendar.getInstance();

     ////当月16

     calendar.set(Calendar.DAY_OF_MONTH, 16 );

     System.out.println(calendar.getTime());

     //当月16

     DateTime now = DateTime.now();

     DateTime dateTime = now.withDayOfMonth( 16 );

     System.out.println(dateTime);

     //当月14

     LocalDateTime localDateTime = LocalDateTime.now();

     System.out.println(localDateTime.withDayOfMonth( 14 ));

     //1月11

     System.out.println(localDateTime.withMonth( 1 ).withDayOfMonth( 11 ));

}

```

//使用SimpleDateFormat

SimpleDateFormat format = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );

System.out.println(format.format( new Date()));

//使用Calendar

Calendar calendar = Calendar.getInstance();

System.out.println(String.format( "%s年%s月%s日%s时%s分%s秒" , calendar.get(Calendar.YEAR),

         calendar.get(Calendar.MONTH) + 1 , calendar.get(Calendar.DAY_OF_MONTH),

         calendar.get(Calendar.HOUR_OF_DAY), calendar.get(Calendar.MINUTE), calendar.get(Calendar.SECOND)));

LocalDateTime now = LocalDateTime.now();

String str = now.format(DateTimeFormatter.ofPattern( "yyyy-MM-dd HH:mm:ss" ));

System.out.println(str);

```

public static void main(String[] args) {

     Date now = new Date();

     //加一小时

     long time = now.getTime() + ( 60 * 60 * 1000 );

     System.out.println( new Date(time));

     /*

     <dependency>

         <groupId>cn.hutool</groupId>

         <artifactId>hutool-all</artifactId>

         <version>5.7.14</version>

     </dependency>

      */

     //引入Hutool 加一小时

     System.out.println(DateUtil.offset(now, DateField.HOUR, 1 ));

     //减一小时

     System.out.println(DateUtil.offset(now, DateField.HOUR, - 1 ));

     LocalDateTime localDateTime = LocalDateTime.now();

     System.out.println( "加一小时" + localDateTime.plusHours( 1 ));

     System.out.println( "减一小时" + localDateTime.minusHours( 1 ));

     DateTime dateTime = DateTime.now();

     System.out.println(dateTime.plusHours( 1 ));

     System.out.println(dateTime.minusHours( 1 ));

}

public static void main(String[] args) {

     //时间1990-12-05

     DateTime birthDay = DateTime.now().withYear( 1990 ).withMonthOfYear( 10 ).withDayOfMonth( 23 );

     System.out.println(birthDay);

     //获取相差得年 会进行月份和日期比较 如

     Years years = Years.yearsBetween(birthDay, new DateTime());

     System.out.println(years);

     System.out.println(years.getYears());

}

public static void main(String[] args) {

     DateTime now = DateTime.now();

     DateTime start1 = now;

     DateTime end1 = now.plusMinutes( 1 );

     DateTime start2 = now.plusSeconds( 50 );

     DateTime end2 = now.plusMinutes( 2 );

     Interval interval1 = new Interval(start1, end1);

     Interval interval2 = new Interval(start2, end2);

     System.out.println(interval1.overlaps(interval2));

     System.out.println(start1.getMillis() < end2.getMillis() && start2.getMillis() < end1.getMillis());

}

public static void main(String[] args) {

     DateTime now = DateTime.now();

     //开始时间

     Date startTime = now.toDate();

     //结束时间

     Date endTime = now.plusHours( 1 ).toDate();

     //1小时

     System.out.println( "开始时间与结束时间的时间间隔:" + DateUtil.between(startTime, endTime, DateUnit.SECOND));

     long time = (endTime.getTime() - startTime.getTime()) / 1000 ;

     System.out.println(time);

}

public static void main(String[] args) throws ParseException {

     Date now = new Date();

     Date utcDate = bj2UTC(now);

     //utc时间

     System.out.println(utcDate);

     //北京时间

     System.out.println(utc2BJ(utcDate));

     DateTime dateTime = DateTime.now().withDayOfMonth( 1 ).withHourOfDay( 0 ).withMinuteOfHour( 0 ).withSecondOfMinute( 0 );

     System.out.println(dateTime);

     System.out.println(bj2UTC(dateTime.toDate()));

}

public static Date bj2UTC(Date date) {

     if (date == null ) {

         return null ;

     }

     LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(), ZoneId.of( "-8" ));

     return Date.from(localDateTime.atOffset(ZoneOffset.UTC).toInstant());

}

public static Date utc2BJ(Date date) {

     if (date == null ) {

         return null ;

     }

     LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(), ZoneId.of( "+8" ));

     return Date.from(localDateTime.atOffset(ZoneOffset.UTC).toInstant());

}