java.time包：
这是新的Java日期/时间API的基础包，所有的主要基础类都是这个包的一部分，如：LocalDate, LocalTime, LocalDateTime, Instant, Period, Duration等等。所有这些类都是不可变的和线程安全的，在绝大多数情况下，这些类能够有效地处理一些公共的需求。
Instant——它代表的是时间戳
LocalDate——不包含具体时间的日期，比如2014-01-14。它可以用来存储生日，周年纪念日，入职日期等。
LocalTime——它代表的是不含日期的时间
LocalDateTime——它包含了日期及时间，不过还是没有偏移信息或者说时区。
ZonedDateTime——这是一个包含时区的完整的日期时间，偏移量是以UTC/格林威治时间为基准的。
java.time.chrono包：
这个包为非ISO的日历系统定义了一些泛化的API，我们可以扩展AbstractChronology类来创建自己的日历系统。
java.time.format包：
这个包包含能够格式化和解析日期时间对象的类，在绝大多数情况下，我们不应该直接使用它们，因为java.time包中相应的类已经提供了格式化和解析的方法。
java.time.temporal包：
这个包包含一些时态对象，我们可以用其找出关于日期/时间对象的某个特定日期或时间，比如说，可以找到某月的第一天或最后一天。你可以非常容易地认出这些方法，因为它们都具有“withXXX”的格式。
java.time.zone包：
这个包包含支持不同时区以及相关规则的类。
java8处理时间及日期
1.LocalDate
LocalDate是一个不可变的类，它表示默认格式(yyyy-MM-dd)的日期，我们可以使用now()方法得到当前时间，也可以提供输入年份、月份和日期的输入参数来创建一个LocalDate实例。该类为now()方法提供了重载方法，我们可以传入ZoneId来获得指定时区的日期。该类提供与java.sql.Date相同的功能，对于如何使用该类，我们来看一个简单的例子。
public class LocalDateExample {
public static void main(String[] args) {
//Current Date
LocalDate today = LocalDate.now();
System.out.println("Current Date="+today);
//Creating LocalDate by providing input arguments
LocalDate firstDay_2014 = LocalDate.of(2014, Month.JANUARY, 1);
System.out.println("Specific Date="+firstDay_2014);
//Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalDate todayKolkata = LocalDate.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Date in IST="+todayKolkata);
//java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
//LocalDate todayIST = LocalDate.now(ZoneId.of("IST"));
//Getting date from the base date i.e 01/01/1970
LocalDate dateFromBase = LocalDate.ofEpochDay(365);
System.out.println("365th day from base date= "+dateFromBase);
LocalDate hundredDay2014 = LocalDate.ofYearDay(2014, 100);
System.out.println("100th day of 2014="+hundredDay2014);
}
}
//输出
Current Date=2014-04-28
Specific Date=2014-01-01
Current Date in IST=2014-04-29
365th day from base date= 1971-01-01
100th day of 2014=2014-04-1
2.LocalTime
LocalTime是一个不可变的类，它的实例代表一个符合人类可读格式的时间，默认格式是hh:mm:ss.zzz。像LocalDate一样，该类也提供了时区支持，同时也可以传入小时、分钟和秒等输入参数创建实例，我们来看一个简单的程序，演示该类的使用方法。
public class LocalTimeExample {
public static void main(String[] args) {
//Current Time
LocalTime time = LocalTime.now();
System.out.println("Current Time="+time);
//Creating LocalTime by providing input arguments
LocalTime specificTime = LocalTime.of(12,20,25,40);
System.out.println("Specific Time of Day="+specificTime);
//Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalTime timeKolkata = LocalTime.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Time in IST="+timeKolkata);
//java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
//LocalTime todayIST = LocalTime.now(ZoneId.of("IST"));
//Getting date from the base date i.e 01/01/1970
LocalTime specificSecondTime = LocalTime.ofSecondOfDay(10000);
System.out.println("10000th second time= "+specificSecondTime);
}
}
//输出
Current Time=15:51:45.240
Specific Time of Day=12:20:25.000000040
Current Time in IST=04:21:45.276
10000th second time= 02:46:40
3.LocalDateTime
LocalDateTime是一个不可变的日期-时间对象，它表示一组日期-时间，默认格式是yyyy-MM-dd-HH-mm-ss.zzz。它提供了一个工厂方法，接收LocalDate和LocalTime输入参数，创建LocalDateTime实例。我们来看一个简单的例子。
public class LocalDateTimeExample {
public static void main(String[] args) {
//Current Date
LocalDateTime today = LocalDateTime.now();
System.out.println("Current DateTime="+today);
//Current Date using LocalDate and LocalTime
today = LocalDateTime.of(LocalDate.now(), LocalTime.now());
System.out.println("Current DateTime="+today);
//Creating LocalDateTime by providing input arguments
LocalDateTime specificDate = LocalDateTime.of(2014, Month.JANUARY, 1, 10, 10, 30);
System.out.println("Specific Date="+specificDate);
//Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalDateTime todayKolkata = LocalDateTime.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Date in IST="+todayKolkata);
//java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
//LocalDateTime todayIST = LocalDateTime.now(ZoneId.of("IST"));
//Getting date from the base date i.e 01/01/1970
LocalDateTime dateFromBase = LocalDateTime.ofEpochSecond(10000, 0, ZoneOffset.UTC);
System.out.println("10000th second time from 01/01/1970= "+dateFromBase);
}
}
//输出
Current DateTime=2014-04-28T16:00:49.455
Current DateTime=2014-04-28T16:00:49.493
Specific Date=2014-01-01T10:10:30
Current Date in IST=2014-04-29T04:30:49.493
10000th second time from 01/01/1970= 1970-01-01T02:46:40
4.Instant
Instant类是用在机器可读的时间格式上的，它以Unix时间戳的形式存储日期时间，我们来看一个简单的程序。
public class InstantExample {
public static void main(String[] args) {
//Current timestamp
Instant timestamp = Instant.now();
System.out.println("Current Timestamp = "+timestamp);
//Instant from timestamp
Instant specificTime = Instant.ofEpochMilli(timestamp.toEpochMilli());
System.out.println("Specific Time = "+specificTime);
//Duration example
Duration thirtyDay = Duration.ofDays(30);
System.out.println(thirtyDay);
}
}
//输出
Current Timestamp = 2014-04-28T23:20:08.489Z
Specific Time = 2014-04-28T23:20:08.489Z
PT720H
5.日期API工具
我们早些时候提到过，大多数日期/时间API类都实现了一系列工具方法，如：加/减天数、周数、月份数，等等。还有其他的工具方法能够使用TemporalAdjuster调整日期，并计算两个日期间的周期。
public class DateAPIUtilities {
public static void main(String[] args) {
LocalDate today = LocalDate.now();
//Get the Year, check if it's leap year
System.out.println("Year "+today.getYear()+" is Leap Year? "+today.isLeapYear());
//Compare two LocalDate for before and after
System.out.println("Today is before 01/01/2015? "+today.isBefore(LocalDate.of(2015,1,1)));
//Create LocalDateTime from LocalDate
System.out.println("Current Time="+today.atTime(LocalTime.now()));
//plus and minus operations
System.out.println("10 days after today will be "+today.plusDays(10));
System.out.println("3 weeks after today will be "+today.plusWeeks(3));
System.out.println("20 months after today will be "+today.plusMonths(20));
System.out.println("10 days before today will be "+today.minusDays(10));
System.out.println("3 weeks before today will be "+today.minusWeeks(3));
System.out.println("20 months before today will be "+today.minusMonths(20));
//Temporal adjusters for adjusting the dates
System.out.println("First date of this month= "+today.with(TemporalAdjusters.firstDayOfMonth()));
LocalDate lastDayOfYear = today.with(TemporalAdjusters.lastDayOfYear());
System.out.println("Last date of this year= "+lastDayOfYear);
Period period = today.until(lastDayOfYear);
System.out.println("Period Format= "+period);
System.out.println("Months remaining in the year= "+period.getMonths());
}
}
//输出
Year 2014 is Leap Year? false
Today is before 01/01/2015? true
Current Time=2014-04-28T16:23:53.154
10 days after today will be 2014-05-08
3 weeks after today will be 2014-05-19
20 months after today will be 2015-12-28
10 days before today will be 2014-04-18
3 weeks before today will be 2014-04-07
20 months before today will be 2012-08-28
First date of this month= 2014-04-01
Last date of this year= 2014-12-31
Period Format= P8M3D
Months remaining in the year= 8
6.解析和格式化
public class GetDate {
public final static String YYYYMMDD = "yyyy-MM-dd";
public final static String YEAR_MONTH_DAY = "yyyy年MM月dd日";
public final static String YYYYMMDDHHMMSS = "yyyy-MM-dd HH:mm:ss";
public final static String YYYYMMDDHHMMSSSSS = "yyyyMMddHHmmssSSS";
public final static String YYYYMMDDHHMMSS_NOSIGN = "yyyyMMddHHmmss";
public final static String YYYYMMDD_1 = "yyyyMMdd";
// ---------------------------- Formatter ---------------------------
/**
* 2018-05-31
*/
public final static DateTimeFormatter FORMATTER_LOCAL = DateTimeFormatter.ISO_LOCAL_DATE;
/**
* 2018年05月31日
*/
public final static DateTimeFormatter FORMATTER_YEAR_MONTH_DAY = DateTimeFormatter.ofPattern(YEAR_MONTH_DAY);
/**
* 2018-05-31 11:12:42
*/
public final static DateTimeFormatter FORMATTER_YYYYMMDDHHMMSS = DateTimeFormatter.ofPattern(YYYYMMDDHHMMSS);
/**
* 20180531110806694
*/
public final static DateTimeFormatter FORMATTER_YYYYMMDDHHMMSSSSS = DateTimeFormatter.ofPattern(YYYYMMDDHHMMSSSSS);
/**
* 20180629173455
*/
public final static DateTimeFormatter FORMATTER_YYYYMMDDHHMMSS_NOSIGN = DateTimeFormatter.ofPattern(YYYYMMDDHHMMSS_NOSIGN);
/**
* 2018-05-31
*/
public final static DateTimeFormatter FORMATTER_YYYYMMDD = DateTimeFormatter.ofPattern(YYYYMMDD);
public final static DateTimeFormatter FORMATTER_YYYYMMDD_1 = DateTimeFormatter.ofPattern(YYYYMMDD_1);
/**
* 获取当前时间，并格式化成给定格式
*
* @param formatter
* @return
*/
public static String getNowTimeString(DateTimeFormatter formatter) {
LocalDateTime now = LocalDateTime.now();
return now.format(formatter);
}
/**
* 获取当前时间Unix格式 (10位int)
*
* @return
*/
public static Integer getNowTimeUnix() {
LocalDateTime now = LocalDateTime.now();
return (int) now.toEpochSecond(ZoneOffset.of("+8"));
}
/**
* Unix时间戳格式化成String
*
* @param unixTime
* @param formatter
* @return
*/
public static String unixToString(int unixTime, DateTimeFormatter formatter) {
Instant instant = Instant.ofEpochSecond(unixTime);
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneOffset.of("+8"));
return localDateTime.format(formatter);
}
/**
* String格式时间转换成Unix时间戳
*
* @param timeStr "yyyy-MM-dd HH:mm:ss" 这种格式
* @param formatter
* @return
*/
public static int stringToUnix(String timeStr) {
if (timeStr.length() == 10) {
timeStr = timeStr + " 00:00:00";
}
LocalDateTime localDateTime = LocalDateTime.parse(timeStr, FORMATTER_YYYYMMDDHHMMSS);
return (int) localDateTime.toEpochSecond(ZoneOffset.of("+8"));
}
/**
* String格式时间转换成Unix时间戳
*
* @param timeStr "yyyy-MM-dd" 这种格式
* @param formatter
* @return
*/
public static int stringToUnix(String timeStr, DateTimeFormatter formatter) {
if (timeStr.length() == 10) {
timeStr = timeStr + " 00:00:00";
}
LocalDateTime localDateTime = LocalDateTime.parse(timeStr, FORMATTER_YYYYMMDDHHMMSS);
return (int) localDateTime.toEpochSecond(ZoneOffset.of("+8"));
}
/**
* 获得时间开始 例：传入 2015-12-03 返回 2015-12-03 00:00:00
*
* @param curDate
* @return
*/
public static String getDayStart(String curDate) {
return curDate + " 00:00:00";
}
/**
* 获得时间结束 例：传入 2015-12-03 返回 2015-12-03 23:59:59
*
* @param curDate
* @return
*/
public static String getDayEnd(String curDate) {
return curDate + " 23:59:59";
}
/**
* 获取秒值
*
* @return
*/
public static Integer getMyTimeInMillis() {
// 当前时间
long milliseconds = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli() / 1000;
return (int) milliseconds;
}
/**
* 时间戳 去掉时分秒
* @param unixTime
* @return
*/
public static Integer getYYYYMMDDUnix(Integer unixTime){
Instant instant = Instant.ofEpochSecond(unixTime);
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneOffset.of("+8"));
return GetDate.stringToUnix(localDateTime.format(GetDate.FORMATTER_YYYYMMDD));
}
}