新Date類和Time類背后的設計原則：
不可變類
java8之前，Date類都是可變類。當我們在多線程環境下使用它，編程人員應該確認Date對象的線程安全。Java8的Date和Time API提供了線程安全的不可變類。編程人員不用考慮并發的問題。
領域模型驅動設計方法
新的日期和時間的類別遵循“域驅動設計”。對于開發者來說，理解方法和類的功能是很容易的。
接下來讓我們來看看新Date和Time API:
1.java.time.LocalDate:
LocalDate只提供日期不提供時間信息。它是不可變類且線程安全的。
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package org.smarttechie;import java.time.LocalDate;import java.time.temporal.ChronoUnit;/*** This class demonstrates JAVA 8 data and time API* @author Siva Prasad Rao Janapati* */public class DateTimeDemonstration {/*** @param args*/public static void main(String[] args) { //Create date LocalDate localDate = LocalDate.now(); System.out.println("The local date is :: " + localDate); //Find the length of the month. That is, how many days are there for this month. System.out.println("The number of days available for this month:: " + localDate.lengthOfMonth()); //Know the month name System.out.println("What is the month name? :: " + localDate.getMonth().name()); //add 2 days to the today's date. System.out.println(localDate.plus(2, ChronoUnit.DAYS)); //substract 2 days from today System.out.println(localDate.minus(2, ChronoUnit.DAYS)); //Convert the string to date System.out.println(localDate.parse("2017-04-07")); }} |
2.java.time.LocalTime:
LocalTime只提供時間而不提供日期信息，它是不可變類且線程安全的。
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package org.smarttechie;import java.time.LocalTime;import java.time.temporal.ChronoUnit;/*** This class demonstrates JAVA 8 data and time API* @author Siva Prasad Rao Janapati* */public class DateTimeDemonstration {/*** @param args*/public static void main(String[] args) { //Get local time LocalTime localTime = LocalTime.now(); System.out.println(localTime); //Get the hour of the day System.out.println("The hour of the day:: " + localTime.getHour()); //add 2 hours to the time. System.out.println(localTime.plus(2, ChronoUnit.HOURS)); //add 6 minutes to the time. System.out.println(localTime.plusMinutes(6)); //substract 2 hours from current time System.out.println(localTime.minus(2, ChronoUnit.HOURS)); }} |
3.java.time.LocalDateTime:
LocalDateTime提供時間和日期的信息，它是不可變類且線程安全的
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package orr.smarttechie;import java.time.LocalDateTime;import java.time.temporal.ChronoUnit;/*** This class demonstrates JAVA 8 data and time API* @author Siva Prasad Rao Janapati**/public class DateTimeDemonstration {/*** @param args*/public static void main(String[] args) { //Get LocalDateTime object LocalDateTime localDateTime = LocalDateTime.now(); System.out.println(localDateTime); //Find the length of month. That is, how many days are there for this month. System.out.println("The number of days available for this month:: " + localDateTime.getMonth().length(true)); //Know the month name System.out.println("What is the month name? :: " + localDateTime.getMonth().name()); //add 2 days to today's date. System.out.println(localDateTime.plus(2, ChronoUnit.DAYS)); //substract 2 days from today System.out.println(localDateTime.minus(2, ChronoUnit.DAYS)); }} |
4.java.time.Year:
Year提供年的信息，它是不可變類且線程安全的。
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package orr.smarttechie;import java.time.Year;import java.time.temporal.ChronoUnit;/*** This class demonstrates JAVA 8 data and time API* @author Siva Prasad Rao Janapati**/public class DateTimeDemonstration {/*** @param args*/public static void main(String[] args) { //Get year Year year = Year.now(); System.out.println("Year ::" + year); //know the year is leap year or not System.out.println("Is year[" +year+"] leap year?"+ year.isLeap()); }} |
5.java.time.Duration:
Duration是用來計算兩個給定的日期之間包含多少秒，多少毫秒，它是不可變類且線程安全的
6.java.time.Period:
Period是用來計算兩個給定的日期之間包含多少天，多少月或者多少年，它是不可變類且線程安全的
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package orr.smarttechie;import java.time.LocalDate;import java.time.Period;import java.time.temporal.ChronoUnit;/*** This class demonstrates JAVA 8 data and time API* @author Siva Prasad Rao Janapati**/public class DateTimeDemonstration {/*** @param args*/public static void main(String[] args) { LocalDate localDate = LocalDate.now(); Period period = Period.between(localDate, localDate.plus(2, ChronoUnit.DAYS)); System.out.println(period.getDays()); }} |
