五、（二）Java 8特性 java.time包的应用

import java.time.*;
import java.time.chrono.ChronoLocalDateTime;
import java.time.chrono.Chronology;
import java.time.chrono.HijrahChronology;
import java.time.format.DateTimeFormatter;
import java.time.temporal.IsoFields;
import java.util.Date;

public class TimeDemo {

        public static void testClock() throws InterruptedException {
            //时钟提供给我们用于访问某个特定 时区的 瞬时时间、日期 和 时间的。
            Clock c1 = Clock.systemUTC(); //系统默认UTC时钟（当前瞬时时间 System.currentTimeMillis()）
            System.out.println(c1.millis()); //每次调用将返回当前瞬时时间（UTC）
            Clock c2 = Clock.systemDefaultZone(); //系统默认时区时钟（当前瞬时时间）
            Clock c31 = Clock.system(ZoneId.of("Europe/Paris")); //巴黎时区
            System.out.println(c31.millis()); //每次调用将返回当前瞬时时间（UTC）
            Clock c32 = Clock.system(ZoneId.of("Asia/Shanghai"));//上海时区
            System.out.println(c32.millis());//每次调用将返回当前瞬时时间（UTC）
            Clock c4 = Clock.fixed(Instant.now(), ZoneId.of("Asia/Shanghai"));//固定上海时区时钟
            System.out.println(c4.millis());
            Thread.sleep(1000);
            System.out.println(c4.millis()); //不变 即时钟时钟在那一个点不动
            Clock c5 = Clock.offset(c1, Duration.ofSeconds(2)); //相对于系统默认时钟两秒的时钟
            System.out.println(c1.millis());//系统默认时钟
            System.out.println(c5.millis());//系统默认始终两秒后
        }
        public static void testInstant() {
            //瞬时时间(instant意为瞬间) 相当于以前的System.currentTimeMillis()
            Instant instant1 = Instant.now();
            System.out.println(instant1.getEpochSecond());//精确到秒 得到相对于1970-01-01 00:00:00 UTC的一个时间
            System.out.println(instant1.toEpochMilli()); //精确到毫秒
            Clock clock1 = Clock.systemUTC(); //获取系统UTC默认时钟
            Instant instant2 = Instant.now(clock1);//得到时钟的瞬时时间
            System.out.println(instant2.toEpochMilli());
            Clock clock2 = Clock.fixed(instant1, ZoneId.systemDefault()); //固定瞬时时间时钟
            Instant instant3 = Instant.now(clock2);//得到时钟的瞬时时间
            System.out.println(instant3.toEpochMilli());//equals instant1
        }
        public static void testLocalDateTime() {
            //使用默认时区时钟瞬时时间创建 Clock.systemDefaultZone() -->即相对于 ZoneId.systemDefault()默认时区
            LocalDateTime now = LocalDateTime.now();
            System.out.println(now);
            //自定义时区
            LocalDateTime now2 = LocalDateTime.now(ZoneId.of("Europe/Paris"));
            System.out.println(now2);//会以相应的时区显示日期
            //自定义时钟
            Clock clock = Clock.system(ZoneId.of("Asia/Dhaka"));
            LocalDateTime now3 = LocalDateTime.now(clock);
            System.out.println(now3);//会以相应的时区显示日期
            //不需要写什么相对时间 如java.util.Date 年是相对于1900 月是从0开始
            //2013-12-31 23:59
            LocalDateTime d1 = LocalDateTime.of(2013, 12, 31, 23, 59);
            //年月日 时分秒 纳秒
            LocalDateTime d2 = LocalDateTime.of(2013, 12, 31, 23, 59, 59, 11);
            //使用瞬时时间 + 时区
            Instant instant = Instant.now();
            LocalDateTime d3 = LocalDateTime.ofInstant(Instant.now(), ZoneId.systemDefault());
            System.out.println(d3);
            //解析String--->LocalDateTime
            LocalDateTime d4 = LocalDateTime.parse("2013-12-31T23:59");
            System.out.println(d4);
            LocalDateTime d5 = LocalDateTime.parse("2013-12-31T23:59:59.999");//999毫秒 等价于999000000纳秒
            System.out.println(d5);
            //使用DateTimeFormatter API 解析 和 格式化
            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
            LocalDateTime d6 = LocalDateTime.parse("2013/12/31 23:59:59", formatter);
            System.out.println(formatter.format(d6));
            //时间获取
            System.out.println(d6.getYear());
            System.out.println(d6.getMonth());
            System.out.println(d6.getDayOfYear());
            System.out.println(d6.getDayOfMonth());
            System.out.println(d6.getDayOfWeek());
            System.out.println(d6.getHour());
            System.out.println(d6.getMinute());
            System.out.println(d6.getSecond());
            System.out.println(d6.getNano());
            //时间增减
            LocalDateTime d7 = d6.minusDays(1);
            LocalDateTime d8 = d7.plus(1, IsoFields.QUARTER_YEARS);
            //LocalDate 即年月日 无时分秒
            //LocalTime即时分秒 无年月日
            //API和LocalDateTime类似就不演示了
        }
        public static void testZonedDateTime() {
            //即带有时区的date-time 存储纳秒、时区和时差（避免与本地date-time歧义）。
            //API和LocalDateTime类似，只是多了时差(如2013-12-20T10:35:50.711+08:00[Asia/Shanghai])
            ZonedDateTime now = ZonedDateTime.now();
            System.out.println(now);
            ZonedDateTime now2 = ZonedDateTime.now(ZoneId.of("Europe/Paris"));
            System.out.println(now2);
            //其他的用法也是类似的 就不介绍了
            ZonedDateTime z1 = ZonedDateTime.parse("2013-12-31T23:59:59Z[Europe/Paris]");
            System.out.println(z1);
        }
        public static void testDuration() {
            //表示两个瞬时时间的时间段
            Duration d1 = Duration.between(Instant.ofEpochMilli(System.currentTimeMillis() - 12323123), Instant.now());
            //得到相应的时差
            System.out.println(d1.toDays());
            System.out.println(d1.toHours());
            System.out.println(d1.toMinutes());
            System.out.println(d1.toMillis());
            System.out.println(d1.toNanos());
            //1天时差 类似的还有如ofHours()
            Duration d2 = Duration.ofDays(1);
            System.out.println(d2.toDays());
        }
        public static void testChronology() {
            //提供对java.util.Calendar的替换，提供对年历系统的支持
            Chronology c = HijrahChronology.INSTANCE;
            ChronoLocalDateTime d = c.localDateTime(LocalDateTime.now());
            System.out.println(d);
        }
        /**
         * 新旧日期转换
         */
        public static void testNewOldDateConversion(){
            Instant instant=new Date().toInstant();
            Date date=Date.from(instant);
            System.out.println(instant);
            System.out.println(date);
        }
        public static void main(String[] args) throws InterruptedException {
            System.out.println("--------------testClock---------------");
            testClock();
            System.out.println("--------------testInstant---------------");
            testInstant();
            System.out.println("--------------testLocalDataTime---------------");
            testLocalDateTime();
            System.out.println("--------------testZonedDateTime---------------");
            testZonedDateTime();
            System.out.println("--------------testDuration---------------");
            testDuration();
            System.out.println("--------------testChronology---------------");
            testChronology();
            System.out.println("--------------testNewOldDateConversion---------------");
            testNewOldDateConversion();
    }
}

 控制台：

--------------testClock---------------
1540784927482
1540784927572
1540784927572
1540784927572
1540784927572
1540784928573
1540784930574
--------------testInstant---------------
1540784928
1540784928574
1540784928574
1540784928574
--------------testLocalDataTime---------------
2018-10-29T11:48:48.574582200
2018-10-29T04:48:48.574582200
2018-10-29T09:48:48.577584
2018-10-29T11:48:48.577584
2013-12-31T23:59
2013-12-31T23:59:59.999
2013/12/31 23:59:59
2013
DECEMBER
365
31
TUESDAY
23
59
59
0
--------------testZonedDateTime---------------
2018-10-29T11:48:48.638123700+08:00[Asia/Shanghai]
2018-10-29T04:48:48.638624200+01:00[Europe/Paris]
2014-01-01T00:59:59+01:00[Europe/Paris]
--------------testDuration---------------
0
3
205
12323123
12323123635200
1
--------------testChronology---------------
Hijrah-umalqura AH 1440-02-20T11:48:48.657137100
--------------testNewOldDateConversion---------------
2018-10-29T03:48:48.688Z
Mon Oct 29 11:48:48 CST 2018