【愚公系列】2022年01月 Java教学课程 44-时间日期类的高级用法

public class JDK8DateDemo2 {
    public static void main(String[] args) {
        LocalDateTime now = LocalDateTime.now();
        System.out.println(now);

        LocalDateTime localDateTime = LocalDateTime.of(2020, 11, 11, 11, 11, 11);
        System.out.println(localDateTime);
    }
}

public class JDK8DateDemo3 {
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.of(2020, 11, 11, 11, 11, 20);
        //public int getYear()           获取年
        int year = localDateTime.getYear();
        System.out.println("年为" +year);
        //public int getMonthValue()     获取月份（1-12）
        int month = localDateTime.getMonthValue();
        System.out.println("月份为" + month);

        Month month1 = localDateTime.getMonth();
//        System.out.println(month1);

        //public int getDayOfMonth()     获取月份中的第几天（1-31）
        int day = localDateTime.getDayOfMonth();
        System.out.println("日期为" + day);

        //public int getDayOfYear()      获取一年中的第几天（1-366）
        int dayOfYear = localDateTime.getDayOfYear();
        System.out.println("这是一年中的第" + dayOfYear + "天");

        //public DayOfWeek getDayOfWeek()获取星期
        DayOfWeek dayOfWeek = localDateTime.getDayOfWeek();
        System.out.println("星期为" + dayOfWeek);

        //public int getMinute()        获取分钟
        int minute = localDateTime.getMinute();
        System.out.println("分钟为" + minute);
        //public int getHour()           获取小时
  
        int hour = localDateTime.getHour();
        System.out.println("小时为" + hour);
    }
}

public class JDK8DateDemo4 {
    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.of(2020, 12, 12, 8, 10, 12);
        //public LocalDate toLocalDate ()    转换成为一个LocalDate对象
        LocalDate localDate = localDateTime.toLocalDate();
        System.out.println(localDate);

        //public LocalTime toLocalTime ()    转换成为一个LocalTime对象
        LocalTime localTime = localDateTime.toLocalTime();
        System.out.println(localTime);
    }
}

public class JDK8DateDemo5 {
    public static void main(String[] args) {
        //method1();
        //method2();
    }

    private static void method2() {
        //public static LocalDateTime parse (准备解析的字符串, 解析格式) 把一个日期字符串解析成为一个LocalDateTime对象
        String s = "2020年11月12日 13:14:15";
        DateTimeFormatter pattern = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss");
        LocalDateTime parse = LocalDateTime.parse(s, pattern);
        System.out.println(parse);
    }

    private static void method1() {
        LocalDateTime localDateTime = LocalDateTime.of(2020, 11, 12, 13, 14, 15);
        System.out.println(localDateTime);
        //public String format (指定格式)   把一个LocalDateTime格式化成为一个字符串
        DateTimeFormatter pattern = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss");
        String s = localDateTime.format(pattern);
        System.out.println(s);
    }
}

/**
 * JDK8 时间类添加或者减去时间的方法
 */
public class JDK8DateDemo6 {
    public static void main(String[] args) {
        //public LocalDateTime plusYears (long years)   添加或者减去年

        LocalDateTime localDateTime = LocalDateTime.of(2020, 11, 11, 13, 14, 15);
        //LocalDateTime newLocalDateTime = localDateTime.plusYears(1);
        //System.out.println(newLocalDateTime);

        LocalDateTime newLocalDateTime = localDateTime.plusYears(-1);
        System.out.println(newLocalDateTime);
    }
}

/**
 * JDK8 时间类减少或者添加时间的方法
 */
public class JDK8DateDemo7 {
    public static void main(String[] args) {
        //public LocalDateTime minusYears (long years)  减去或者添加年
        LocalDateTime localDateTime = LocalDateTime.of(2020, 11, 11, 13, 14, 15);
        //LocalDateTime newLocalDateTime = localDateTime.minusYears(1);
        //System.out.println(newLocalDateTime);

        LocalDateTime newLocalDateTime = localDateTime.minusYears(-1);
        System.out.println(newLocalDateTime);

    }
}

/**
 * JDK8 时间类修改时间
 */
public class JDK8DateDemo8 {
    public static void main(String[] args) {
        //public LocalDateTime withYear(int year)   修改年
        LocalDateTime localDateTime = LocalDateTime.of(2020, 11, 11, 13, 14, 15);
       // LocalDateTime newLocalDateTime = localDateTime.withYear(2048);
       // System.out.println(newLocalDateTime);

        LocalDateTime newLocalDateTime = localDateTime.withMonth(20);
        System.out.println(newLocalDateTime);

    }
}

/**
 *  计算两个时间的间隔
 */
public class JDK8DateDemo9 {
    public static void main(String[] args) {
        //public static Period between(开始时间,结束时间)  计算两个"时间"的间隔

        LocalDate localDate1 = LocalDate.of(2020, 1, 1);
        LocalDate localDate2 = LocalDate.of(2048, 12, 12);
        Period period = Period.between(localDate1, localDate2);
        System.out.println(period);//P28Y11M11D

        //public int getYears()         获得这段时间的年数
        System.out.println(period.getYears());//28
        //public int getMonths()        获得此期间的月数
        System.out.println(period.getMonths());//11
        //public int getDays()          获得此期间的天数
        System.out.println(period.getDays());//11

        //public long toTotalMonths()   获取此期间的总月数
        System.out.println(period.toTotalMonths());//347

    }
}

/**
 *  计算两个时间的间隔
 */
public class JDK8DateDemo10 {
    public static void main(String[] args) {
        //public static Duration between(开始时间,结束时间)  计算两个“时间"的间隔

        LocalDateTime localDateTime1 = LocalDateTime.of(2020, 1, 1, 13, 14, 15);
        LocalDateTime localDateTime2 = LocalDateTime.of(2020, 1, 2, 11, 12, 13);
        Duration duration = Duration.between(localDateTime1, localDateTime2);
        System.out.println(duration);//PT21H57M58S
        //public long toSeconds()           获得此时间间隔的秒
        System.out.println(duration.toSeconds());//79078
        //public int toMillis()               获得此时间间隔的毫秒
        System.out.println(duration.toMillis());//79078000
        //public int toNanos()             获得此时间间隔的纳秒
        System.out.println(duration.toNanos());//79078000000000
    }
}