jdk8 时间操作类

1、获取当前时间

Instant instant = Instant.now(); //获取当前时间戳

LocalDate localDate = LocalDate.now();  //获取当前日期

LocalTime localTime = LocalTime.now();  //获取当前时刻

LocalDateTime localDateTime = LocalDateTime.now();  //获取当前具体时间

ZonedDateTime zonedDateTime = ZonedDateTime.now();   //获取带有时区的时间

2、 字符串转换时间

String str = "2019-01-11";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate localDate = LocalDate.parse(str, formatter);

3、时间转为字符串

LocalDate localDate = LocalDate.now();
DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
String formatDate = localDate.format(dateTimeFormatter);
System.out.println(formatDate);

4、 Date转为LocalDate

Date date = new Date();
Instant instant = date.toInstant();
ZoneId zoneId = ZoneId.systemDefault();
LocalDate localDate = instant.atZone(zoneId).toLocalDate();
System.out.println(localDate);

5、LocalDate转Date

LocalDate localDate = LocalDate.now();
ZoneId zoneId = ZoneId.systemDefault();
ZonedDateTime zdt = localDate.atStartOfDay(zoneId);
Date date = Date.from(zdt.toInstant());
System.out.println(date);

6、Timestamp转LocalDateTime

long timestamp = System.currentTimeMillis();
Instant instant = Instant.ofEpochMilli(timestamp);
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
System.out.println(localDateTime);

7、LocalDateTime转Timestamp

LocalDateTime localDateTime = LocalDateTime.now();
long epochMilli1 = localDateTime.toInstant(ZoneOffset.ofHours(8)).toEpochMilli();// 写法 1
long epochMilli2 = localDateTime.toInstant(ZoneOffset.of("+08:00")).toEpochMilli();// 写法 2
long epochMilli3 =  localDateTime.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();// 写法 3

8、计算日期之差

LocalDate localDate = LocalDate.now();
LocalDate localDate1 = LocalDate.of(2020, 1, 30);
System.out.println(localDate.until(localDate1, ChronoUnit.DAYS));// 方法一:后面日期大于前面
System.out.println(localDate1.toEpochDay()-localDate.toEpochDay());// 方法二:后面日期大于前面