深入淺析Java8中日期與時(shí)間的特性

Date date = new Date(2012,1,1);
System.out.println(date);

Calendar calendar = Calendar.getInstance();
calendar.set(2013, 8, 2);

calendar.set(2013, Calendar.AUGUST, 2);

public static void main(String[] args) {
  Calendar birth = Calendar.getInstance();
  birth.set(1975, Calendar.MAY, 26);
  Calendar now = Calendar.getInstance();
  System.out.println(daysBetween(birth, now));
  System.out.println(daysBetween(birth, now)); // 顯示 0？
 } 
public static long daysBetween(Calendar begin, Calendar end) {
  long daysBetween = 0;
  while(begin.before(end)) {
    begin.add(Calendar.DAY_OF_MONTH, 1);
    daysBetween++;
  }
  return daysBetween;
}

public static long daysBetween(Calendar begin, Calendar end) {
  Calendar calendar = (Calendar) begin.clone(); // 復(fù)制
  long daysBetween = 0;
  while(calendar.before(end)) {
    calendar.add(Calendar.DAY_OF_MONTH, 1);
    daysBetween++;
  }
  return daysBetween;
}

public class TimeIntroduction {
  public static void testClock() throws InterruptedException {
    //時(shí)鐘提供給我們用于訪問(wèn)某個(gè)特定 時(shí)區(qū)的 瞬時(shí)時(shí)間、日期 和 時(shí)間的。 
    Clock c1 = Clock.systemUTC(); //系統(tǒng)默認(rèn)UTC時(shí)鐘（當(dāng)前瞬時(shí)時(shí)間 System.currentTimeMillis()） 
    System.out.println(c1.millis()); //每次調(diào)用將返回當(dāng)前瞬時(shí)時(shí)間（UTC） 
    Clock c2 = Clock.systemDefaultZone(); //系統(tǒng)默認(rèn)時(shí)區(qū)時(shí)鐘（當(dāng)前瞬時(shí)時(shí)間） 
    Clock c31 = Clock.system(ZoneId.of("Europe/Paris")); //巴黎時(shí)區(qū) 
    System.out.println(c31.millis()); //每次調(diào)用將返回當(dāng)前瞬時(shí)時(shí)間（UTC） 
    Clock c32 = Clock.system(ZoneId.of("Asia/Shanghai"));//上海時(shí)區(qū) 
    System.out.println(c32.millis());//每次調(diào)用將返回當(dāng)前瞬時(shí)時(shí)間（UTC） 
    Clock c4 = Clock.fixed(Instant.now(), ZoneId.of("Asia/Shanghai"));//固定上海時(shí)區(qū)時(shí)鐘 
    System.out.println(c4.millis());
    Thread.sleep(1000);
    System.out.println(c4.millis()); //不變 即時(shí)鐘時(shí)鐘在那一個(gè)點(diǎn)不動(dòng) 
    Clock c5 = Clock.offset(c1, Duration.ofSeconds(2)); //相對(duì)于系統(tǒng)默認(rèn)時(shí)鐘兩秒的時(shí)鐘 
    System.out.println(c1.millis());
    System.out.println(c5.millis());
  }
  public static void testInstant() {
    //瞬時(shí)時(shí)間 相當(dāng)于以前的System.currentTimeMillis() 
    Instant instant1 = Instant.now();
    System.out.println(instant1.getEpochSecond());//精確到秒 得到相對(duì)于1970-01-01 00:00:00 UTC的一個(gè)時(shí)間 
    System.out.println(instant1.toEpochMilli()); //精確到毫秒 
    Clock clock1 = Clock.systemUTC(); //獲取系統(tǒng)UTC默認(rèn)時(shí)鐘 
    Instant instant2 = Instant.now(clock1);//得到時(shí)鐘的瞬時(shí)時(shí)間 
    System.out.println(instant2.toEpochMilli());
    Clock clock2 = Clock.fixed(instant1, ZoneId.systemDefault()); //固定瞬時(shí)時(shí)間時(shí)鐘 
    Instant instant3 = Instant.now(clock2);//得到時(shí)鐘的瞬時(shí)時(shí)間 
    System.out.println(instant3.toEpochMilli());//equals instant1 
  }
  public static void testLocalDateTime() {
    //使用默認(rèn)時(shí)區(qū)時(shí)鐘瞬時(shí)時(shí)間創(chuàng)建 Clock.systemDefaultZone() -->即相對(duì)于 ZoneId.systemDefault()默認(rèn)時(shí)區(qū) 
    LocalDateTime now = LocalDateTime.now();
    System.out.println(now);
//自定義時(shí)區(qū) 
    LocalDateTime now2 = LocalDateTime.now(ZoneId.of("Europe/Paris"));
    System.out.println(now2);//會(huì)以相應(yīng)的時(shí)區(qū)顯示日期 
//自定義時(shí)鐘 
    Clock clock = Clock.system(ZoneId.of("Asia/Dhaka"));
    LocalDateTime now3 = LocalDateTime.now(clock);
    System.out.println(now3);//會(huì)以相應(yīng)的時(shí)區(qū)顯示日期 
//不需要寫什么相對(duì)時(shí)間 如java.util.Date 年是相對(duì)于1900 月是從0開(kāi)始 
//2013-12-31 23:59 
    LocalDateTime d1 = LocalDateTime.of(2013, 12, 31, 23, 59);
//年月日 時(shí)分秒 納秒 
    LocalDateTime d2 = LocalDateTime.of(2013, 12, 31, 23, 59, 59, 11);
//使用瞬時(shí)時(shí)間 + 時(shí)區(qū) 
    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 等價(jià)于999000000納秒 
    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));
//時(shí)間獲取 
    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());
//時(shí)間增減 
    LocalDateTime d7 = d6.minusDays(1);
    LocalDateTime d8 = d7.plus(1, IsoFields.QUARTER_YEARS);
//LocalDate 即年月日 無(wú)時(shí)分秒 
//LocalTime即時(shí)分秒 無(wú)年月日 
//API和LocalDateTime類似就不演示了 
  }
  public static void testZonedDateTime() {
    //即帶有時(shí)區(qū)的date-time 存儲(chǔ)納秒、時(shí)區(qū)和時(shí)差（避免與本地date-time歧義）。 
//API和LocalDateTime類似，只是多了時(shí)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);
//其他的用法也是類似的 就不介紹了 
    ZonedDateTime z1 = ZonedDateTime.parse("2013-12-31T23:59:59Z[Europe/Paris]");
    System.out.println(z1);
  }
  public static void testDuration() {
    //表示兩個(gè)瞬時(shí)時(shí)間的時(shí)間段 
    Duration d1 = Duration.between(Instant.ofEpochMilli(System.currentTimeMillis() - 12323123), Instant.now());
//得到相應(yīng)的時(shí)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天時(shí)差 類似的還有如ofHours() 
    Duration d2 = Duration.ofDays(1);
    System.out.println(d2.toDays());
  }
  public static void testChronology() {
    //提供對(duì)java.util.Calendar的替換，提供對(duì)年歷系統(tǒng)的支持 
    Chronology c = HijrahChronology.INSTANCE;
    ChronoLocalDateTime d = c.localDateTime(LocalDateTime.now());
    System.out.println(d);
  }
  /**
   * 新舊日期轉(zhuǎn)換
   */
  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 {
    testClock();
    testInstant();
    testLocalDateTime();
    testZonedDateTime();
    testDuration();
    testChronology();
    testNewOldDateConversion();
  }
}