“干掉” Date，Java8 LocalDate 真香！

package com.wq.study.java8.date;




import java.time.Clock;

import java.time.Instant;

import java.time.LocalDate;

import java.time.LocalDateTime;

import java.time.LocalTime;

import java.time.Month;

import java.time.MonthDay;

import java.time.OffsetDateTime;

import java.time.ZoneOffset;

import java.time.Period;

import java.time.YearMonth;

import java.time.ZoneId;

import java.time.ZonedDateTime;

import java.time.format.DateTimeFormatter;

import java.time.temporal.ChronoUnit;

import java.util.Date;




public class DateTest {




    //获取今天的日期

    public void getCurrentDate(){

        LocalDate today = LocalDate.now();

        System.out.println("Today's Local date : " + today);




        //这个是作为对比

        Date date = new Date();

        System.out.println(date);

    }




    //获取年、月、日信息

    public void getDetailDate(){

        LocalDate today = LocalDate.now();

        int year = today.getYear();

        int month = today.getMonthValue();

        int day = today.getDayOfMonth();




        System.out.printf("Year : %d  Month : %d  day : %d t %n", year, month, day);

    }




    //处理特定日期

    public void handleSpecilDate(){

        LocalDate dateOfBirth = LocalDate.of(2018, 01, 21);

        System.out.println("The specil date is : " + dateOfBirth);

    }




    //判断两个日期是否相等

    public void compareDate(){

        LocalDate today = LocalDate.now();

        LocalDate date1 = LocalDate.of(2018, 01, 21);




        if(date1.equals(today)){

            System.out.printf("TODAY %s and DATE1 %s are same date %n", today, date1);

        }

    }




    //处理周期性的日期

    public void cycleDate(){

        LocalDate today = LocalDate.now();

        LocalDate dateOfBirth = LocalDate.of(2018, 01, 21);




        MonthDay birthday = MonthDay.of(dateOfBirth.getMonth(), dateOfBirth.getDayOfMonth());

        MonthDay currentMonthDay = MonthDay.from(today);




        if(currentMonthDay.equals(birthday)){

           System.out.println("Many Many happy returns of the day !!");

        }else{

           System.out.println("Sorry, today is not your birthday");

        }

    }




    //获取当前时间

    public void getCurrentTime(){

        LocalTime time = LocalTime.now();

        System.out.println("local time now : " + time);

    }




    //增加小时

    public void plusHours(){

        LocalTime time = LocalTime.now();

        LocalTime newTime = time.plusHours(2); // 增加两小时

        System.out.println("Time after 2 hours : " +  newTime);

    }




    //如何计算一周后的日期

    public void nextWeek(){

        LocalDate today = LocalDate.now();

        LocalDate nextWeek = today.plus(1, ChronoUnit.WEEKS);

        System.out.println("Today is : " + today);

        System.out.println("Date after 1 week : " + nextWeek);

    }




    //计算一年前或一年后的日期

    public void minusDate(){

        LocalDate today = LocalDate.now();

        LocalDate previousYear = today.minus(1, ChronoUnit.YEARS);

        System.out.println("Date before 1 year : " + previousYear);




        LocalDate nextYear = today.plus(1, ChronoUnit.YEARS);

        System.out.println("Date after 1 year : " + nextYear);

    }




    public void clock(){

        // 根据系统时间返回当前时间并设置为UTC。

        Clock clock = Clock.systemUTC();

        System.out.println("Clock : " + clock);




        // 根据系统时钟区域返回时间

        Clock defaultClock = Clock.systemDefaultZone();

        System.out.println("Clock : " + clock);

    }




    //如何用Java判断日期是早于还是晚于另一个日期

    public void isBeforeOrIsAfter(){

        LocalDate today = LocalDate.now();




        LocalDate tomorrow = LocalDate.of(2018, 1, 29);

        if(tomorrow.isAfter(today)){

            System.out.println("Tomorrow comes after today");

        }




        LocalDate yesterday = today.minus(1, ChronoUnit.DAYS);




        if(yesterday.isBefore(today)){

            System.out.println("Yesterday is day before today");

        }

    }




    //时区处理

    public void getZoneTime(){

        //设置时区

        ZoneId america = ZoneId.of("America/New_York");




        LocalDateTime localtDateAndTime = LocalDateTime.now();




        ZonedDateTime dateAndTimeInNewYork  = ZonedDateTime.of(localtDateAndTime, america );

        System.out.println("现在的日期和时间在特定的时区 : " + dateAndTimeInNewYork);

    }




    //使用 YearMonth类处理特定的日期

    public void checkCardExpiry(){

        YearMonth currentYearMonth = YearMonth.now();

        System.out.printf("Days in month year %s: %d%n", currentYearMonth, currentYearMonth.lengthOfMonth());




        YearMonth creditCardExpiry = YearMonth.of(2028, Month.FEBRUARY);

        System.out.printf("Your credit card expires on %s %n", creditCardExpiry);

    }




    //检查闰年

    public void isLeapYear(){

        LocalDate today = LocalDate.now();

        if(today.isLeapYear()){

           System.out.println("This year is Leap year");

        }else {

            System.out.println("2018 is not a Leap year");

        }

    }




    //计算两个日期之间的天数和月数

    public void calcDateDays(){

        LocalDate today = LocalDate.now();




        LocalDate java8Release = LocalDate.of(2018, Month.MAY, 14);




        Period periodToNextJavaRelease = Period.between(today, java8Release);




        System.out.println("Months left between today and Java 8 release : "

                                           + periodToNextJavaRelease.getMonths() );

    }




    // 包含时差信息的日期和时间

    public void ZoneOffset(){

        LocalDateTime datetime = LocalDateTime.of(2018, Month.FEBRUARY, 14, 19, 30);

        ZoneOffset offset = ZoneOffset.of("+05:30");

        OffsetDateTime date = OffsetDateTime.of(datetime, offset);

        System.out.println("Date and Time with timezone offset in Java : " + date);

    }




    // 获取时间戳

    public void getTimestamp(){

        Instant timestamp = Instant.now();

        System.out.println("What is value of this instant " + timestamp);

    }




    // 使用预定义的格式化工具去解析或格式化日期

    public void formateDate(){

        String dayAfterTommorrow = "20180210";

        LocalDate formatted = LocalDate.parse(dayAfterTommorrow, DateTimeFormatter.BASIC_ISO_DATE);

        System.out.printf("Date generated from String %s is %s %n", dayAfterTommorrow, formatted);

    }




    public static void main(String[] args) {

        DateTest dt = new DateTest();




        dt.formateDate();

    }




}