Java8 时间处理举例2

代码：

//      示例1:  Java 8中获取今天的日期
    @Test
    public void test01() {
        LocalTime localTime = LocalTime.now();
        System.out.println("当前时间：" + localTime);

        LocalDate localDate = LocalDate.now();
        System.out.println("当前日期：" + localDate);
    }

    //    示例2:Java 8中获取年、月、日信息
    @Test
    public void test02() {
        LocalDate today = LocalDate.now();
        int year = today.getYear();
        int month = today.getMonthValue();
        int day = today.getDayOfMonth();

        System.out.println("year:" + year);
        System.out.println("month:" + month);
        System.out.println("day:" + day);
    }

    //    示例3:Java 8中处理特定日期
    @Test
    public void test03() {
        LocalDate date = LocalDate.of(2018, 2, 6);
        System.out.println("自定义日期:" + date);
    }

    //    示例4:Java 8中判断两个日期是否相等
    @Test
    public void test04() {
        LocalDate date1 = LocalDate.now();
        LocalDate date2 = LocalDate.of(2018, 2, 5);
        if (date1.equals(date2)) {
            System.out.println("时间相等");
        } else {
            System.out.println("时间不等");
        }
    }

    //    示例5:Java 8中检查像生日这种周期性事件
    @Test
    public void test05() {
        LocalDate date1 = LocalDate.now();

        LocalDate date2 = LocalDate.of(2018, 2, 6);
        MonthDay birthday = MonthDay.of(date2.getMonth(), date2.getDayOfMonth());
        MonthDay currentMonthDay = MonthDay.from(date1);

        if (currentMonthDay.equals(birthday)) {
            System.out.println("是你的生日");
        } else {
            System.out.println("你的生日还没有到");
        }
    }

    //    示例6:Java 8中获取当前时间
    @Test
    public void test06() {
        LocalTime time = LocalTime.now();
        System.out.println("获取当前的时间,不含有日期:" + time);
    }

    //    示例7:Java 8中获取当前时间
    @Test
    public void test07() {
        LocalTime time = LocalTime.now();
        LocalTime newTime = time.plusHours(3);
        System.out.println("三个小时后的时间为:" + newTime);
    }

    //    示例8:Java 8如何计算一周后的日期
    @Test
    public void test08() {
        LocalDate today = LocalDate.now();
        System.out.println("今天的日期为:" + today);
        LocalDate nextWeek = today.plus(1, ChronoUnit.WEEKS);
        System.out.println("一周后的日期为:" + nextWeek);
    }

    //    示例9:Java 8计算一年前或一年后的日期
    @Test
    public void test09() {
        LocalDate today = LocalDate.now();

        LocalDate previousYear = today.minus(1, ChronoUnit.YEARS);
        System.out.println("一年前的日期 : " + previousYear);

        LocalDate nextYear = today.plus(1, ChronoUnit.YEARS);
        System.out.println("一年后的日期:" + nextYear);
    }

    //    示例10:Java 8的Clock时钟类
    @Test
    public void test10() {
        // Returns the current time based on your system clock and set to UTC.
        Clock clock = Clock.systemUTC();
        System.out.println("Clock : " + clock.millis());

        // Returns time based on system clock zone
        Clock defaultClock = Clock.systemDefaultZone();
        System.out.println("Clock : " + defaultClock.millis());
    }

    //    示例11:如何用Java判断日期是早于还是晚于另一个日期
    @Test
    public void test11() {
        LocalDate today = LocalDate.now();

        LocalDate tomorrow = LocalDate.of(2018, 2, 6);
        if (tomorrow.isAfter(today)) {
            System.out.println("之后的日期:" + tomorrow);
        }

        LocalDate yesterday = today.minus(1, ChronoUnit.DAYS);
        if (yesterday.isBefore(today)) {
            System.out.println("之前的日期:" + yesterday);
        }
    }

    //    示例16:在Java 8中获取当前的时间戳
    @Test
    public void test16() {
        Instant timestamp = Instant.now();
        System.out.println("What is value of this instant " + timestamp.toEpochMilli());
    }

    //    示例17:Java 8中如何使用预定义的格式化工具去解析或格式化日期
    @Test
    public void test17() {
        String dayAfterTommorrow = "20180205";
        LocalDate formatted = LocalDate.parse(dayAfterTommorrow,
                DateTimeFormatter.BASIC_ISO_DATE);
        System.out.println(dayAfterTommorrow + "  格式化后的日期为:  " + formatted);
    }


    //    示例18:字符串互转日期类型
    @Test
    public void test18() {
        LocalDateTime date = LocalDateTime.now();

        DateTimeFormatter format1 = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
        //日期转字符串
        String str = date.format(format1);

        System.out.println("日期转换为字符串:" + str);

        DateTimeFormatter format2 = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
        //字符串转日期
        LocalDate date2 = LocalDate.parse(str, format2);
        System.out.println("日期类型:" + date2);
    }

参考文章：

https://mp.weixin.qq.com/s/jb3GTiQUeGRq0rF_gfVbIQ