[Java知识库]Java8实战系列 —— 新的日期和时间Api

public class DateTest {

    @Test
    public void test1(){
        LocalDate date = LocalDate.of(2022, 3, 1);
        System.out.println(date.getYear());
        System.out.println(date.getMonth());
        System.out.println(date.getDayOfWeek());
        System.out.println(date.getDayOfMonth());
        System.out.println(date.lengthOfMonth());
    }

    @Test
    public void test2(){
        LocalDate now = LocalDate.now();
        System.out.println(now);

        LocalTime time = LocalTime.now();
        System.out.println(time);
        System.out.println(time.getHour());
    }

    @Test
    public void test3(){
        LocalDate date = LocalDate.now();
        LocalTime time = LocalTime.now();

        LocalDateTime dateTime = LocalDateTime.of(date, time);
        System.out.println(dateTime);

        System.out.println(dateTime.toLocalDate());
    }

    @Test
    public void test4(){
        LocalTime time1 = LocalTime.now();
        LocalTime time2 = LocalTime.now();
        Duration duration = Duration.between(time1, time2);
        System.out.println(duration);


        Period period = Period.between(LocalDate.of(2022, 3, 1), LocalDate.of(2022, 2, 25));
        System.out.println(period);
    }

    @Test
    public void test5(){
        LocalDate date = LocalDate.of(2022, 2, 20);
        LocalDate date1 = date.withMonth(4);
        System.out.println(date1);

        LocalDate date2 = date.plusDays(5);
        System.out.println(date2);
        LocalDate date3 = date.minusDays(5);
        System.out.println(date3);
    }

    @Test
    public void test6(){
        LocalDate date = LocalDate.of(2022, 2, 20);
        String s1 = date.format(DateTimeFormatter.ISO_LOCAL_DATE);
        String s2 = date.format(DateTimeFormatter.BASIC_ISO_DATE);
        System.out.println(s1);// 2022-02-20
        System.out.println(s2);// 20220220
    }

    @Test
    public void test7(){
        LocalDate date1 = LocalDate.parse("2022-02-20", DateTimeFormatter.ISO_LOCAL_DATE);
        LocalDate date2 = LocalDate.parse("20220220", DateTimeFormatter.BASIC_ISO_DATE);
        System.out.println(date1);
        System.out.println(date2);
    }

    @Test
    public void test8(){
        //模板创建DateTimeFormatter
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd");
        LocalDate date = LocalDate.now();
        String s = date.format(formatter);
        System.out.println(s);

        //根据模板转回date对象
        LocalDate localDate = LocalDate.parse(s, formatter);
        System.out.println(localDate);
    }

}