java.time.Clock#system ( )源码实例Demo

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());
    System.out.println(c5.millis());
}
 

@Override
public Object unmarshal(final HierarchicalStreamReader reader, final UnmarshallingContext context) {
    reader.moveDown();
    final ZoneId zone = (ZoneId)context.convertAnother(null, ZoneId.class);
    reader.moveUp();
    return Clock.system(zone);
}
 

@Test
public void test_ThaiBuddhistChronology_dateNow() {
    ZoneId zoneId_paris = ZoneId.of("Europe/Paris");
    Clock clock = Clock.system(zoneId_paris);

    Chronology chrono = Chronology.of("ThaiBuddhist");
    assertEquals(chrono.dateNow(), ThaiBuddhistChronology.INSTANCE.dateNow());
    assertEquals(chrono.dateNow(zoneId_paris), ThaiBuddhistChronology.INSTANCE.dateNow(zoneId_paris));
    assertEquals(chrono.dateNow(clock), ThaiBuddhistChronology.INSTANCE.dateNow(clock));
}
 

@Test
public void test_MinguoChronology_dateNow() {
    ZoneId zoneId_paris = ZoneId.of("Europe/Paris");
    Clock clock = Clock.system(zoneId_paris);

    Chronology chrono = Chronology.of("Minguo");
    assertEquals(chrono.dateNow(), MinguoChronology.INSTANCE.dateNow());
    assertEquals(chrono.dateNow(zoneId_paris), MinguoChronology.INSTANCE.dateNow(zoneId_paris));
    assertEquals(chrono.dateNow(clock), MinguoChronology.INSTANCE.dateNow(clock));
}
 

@Test
public void test_JapaneseChronology_dateNow() {
    ZoneId zoneId_paris = ZoneId.of("Europe/Paris");
    Clock clock = Clock.system(zoneId_paris);

    Chronology chrono = Chronology.of("Japanese");
    assertEquals(chrono.dateNow(), JapaneseChronology.INSTANCE.dateNow());
    assertEquals(chrono.dateNow(zoneId_paris), JapaneseChronology.INSTANCE.dateNow(zoneId_paris));
    assertEquals(chrono.dateNow(clock), JapaneseChronology.INSTANCE.dateNow(clock));
}
 

@Test
public void test_ThaiBuddhistChronology_dateNow() {
    ZoneId zoneId_paris = ZoneId.of("Europe/Paris");
    Clock clock = Clock.system(zoneId_paris);

    Chronology chrono = Chronology.of("ThaiBuddhist");
    assertEquals(chrono.dateNow(), ThaiBuddhistChronology.INSTANCE.dateNow());
    assertEquals(chrono.dateNow(zoneId_paris), ThaiBuddhistChronology.INSTANCE.dateNow(zoneId_paris));
    assertEquals(chrono.dateNow(clock), ThaiBuddhistChronology.INSTANCE.dateNow(clock));
}
 

public void test_withZone_same() {
    Clock test = Clock.system(PARIS);
    Clock changed = test.withZone(PARIS);
    assertSame(test, changed);
}
 

@Test(expectedExceptions = NullPointerException.class)
public void test_zoneId_nullZoneId() {
    Clock.system(null);
}
 

public void test_withZone() {
    Clock test = Clock.system(PARIS);
    Clock changed = test.withZone(MOSCOW);
    assertEquals(test.getZone(), PARIS);
    assertEquals(changed.getZone(), MOSCOW);
}
 

public void test_withZone_same() {
    Clock test = Clock.system(PARIS);
    Clock changed = test.withZone(PARIS);
    assertSame(test, changed);
}
 

public void test_toString() {
    Clock test = Clock.system(PARIS);
    assertEquals(test.toString(), "SystemClock[Europe/Paris]");
}
 

public void test_system_ZoneId() {
    Clock test = Clock.system(PARIS);
    assertEquals(test.getZone(), PARIS);
}
 

public void test_tick_ClockDuration_1nsDuration() {
    Clock underlying = Clock.system(PARIS);
    Clock test = Clock.tick(underlying, Duration.ofNanos(1));
    assertSame(test, underlying);  // spec says same
}
 

public void test_tick_ClockDuration_zeroDuration() {
    Clock underlying = Clock.system(PARIS);
    Clock test = Clock.tick(underlying, Duration.ZERO);
    assertSame(test, underlying);  // spec says same
}
 

@Test(expectedExceptions = NullPointerException.class)
public void test_zoneId_nullZoneId() {
    Clock.system(null);
}
 

public void test_system_ZoneId() {
    Clock test = Clock.system(PARIS);
    assertEquals(test.getZone(), PARIS);
}
 

public void test_tick_ClockDuration_zeroDuration() {
    Clock underlying = Clock.system(PARIS);
    Clock test = Clock.tick(underlying, Duration.ZERO);
    assertSame(test, underlying);  // spec says same
}
 

public void test_withZone_equal() {
    Clock test = Clock.system(PARIS);
    Clock changed = test.withZone(PARIS);
    assertEquals(changed.getZone(), PARIS);
}
 

public void test_system_ZoneId() {
    Clock test = Clock.system(PARIS);
    assertEquals(test.getZone(), PARIS);
}
 

public void test_toString() {
    Clock test = Clock.system(PARIS);
    assertEquals(test.toString(), "SystemClock[Europe/Paris]");
}