Java8新特性_日期時間新類 LocalDate、LocalTime、LocalDateTime
阿新 • • 發佈：2019-01-26
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import java.text.SimpleDateFormat; import java.time.LocalDate; import java.time.format.DateTimeFormatter; import java.util.ArrayList; import java.util.Date; import java.util.List; import java.util.concurrent.Callable; import java.util.concurrent.ExecutionException; import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors; import java.util.concurrent.Future; public class TestSimpleDateFormat { public static void main(String[] args) throws Exception { // oldDateMethod(); // oldDateMethodThreadSafe(); java8DateMethodThreadSave(); } /**線程不安全，報錯*/ public static void oldDateMethod() throws Exception{ SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd"); Callable<Date> task = new Callable<Date>() { @Override public Date call() throws Exception { return sdf.parse("20161121"); } }; ExecutorService pool= Executors.newFixedThreadPool(10); List<Future<Date>> results = new ArrayList<>(); for (int i = 0; i < 10; i++) { results.add(pool.submit(task)); } for (Future<Date> future : results) { System.out.println(future.get()); } pool.shutdown(); } //解決多線程安全問題 public static void oldDateMethodThreadSafe() throws Exception{ Callable<Date> task = new Callable<Date>() { @Override public Date call() throws Exception { return DateFormatThreadLocal.convert("20161121"); } }; ExecutorService pool = Executors.newFixedThreadPool(10); List<Future<Date>> results = new ArrayList<>(); for (int i = 0; i < 10; i++) { results.add(pool.submit(task)); } for (Future<Date> future : results) { System.out.println(future.get()); } pool.shutdown(); } /**java8的實現*/ public static void java8DateMethodThreadSave() throws Exception{ DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyyMMdd"); Callable<LocalDate> task = new Callable<LocalDate>() { @Override public LocalDate call() throws Exception { LocalDate ld = LocalDate.parse("20161121", dtf); return ld; } }; ExecutorService pool = Executors.newFixedThreadPool(10); List<Future<LocalDate>> results = new ArrayList<>(); for (int i = 0; i < 10; i++) { results.add(pool.submit(task)); } for (Future<LocalDate> future : results) { System.out.println(future.get()); } pool.shutdown(); } }
import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; public class DateFormatThreadLocal { private static final ThreadLocal<DateFormat> df = new ThreadLocal<DateFormat>(){ protected DateFormat initialValue(){ return new SimpleDateFormat("yyyyMMdd"); } }; public static final Date convert(String source) throws ParseException { return df.get().parse(source); } }
LocalDate、LocalTime、LocalDateTime 類的實 例是不可變的對象，分別表示使用 ISO-8601日 歷系統的日期、時間、日期和時間。它們提供 了簡單的日期或時間，並不包含當前的時間信 息。也不包含與時區相關的信息。
Instant 時間戳
用於“時間戳”的運算。它是以Unix元年(傳統 的設定為UTC時區1970年1月1日午夜時分)開始 所經歷的描述進行運算
Duration 和 Period
Duration : 用於計算兩個“時間”間隔
Period : 用於計算兩個“日期”間隔
import java.time.DayOfWeek; import java.time.Duration; import java.time.Instant; import java.time.LocalDate; import java.time.LocalDateTime; import java.time.OffsetDateTime; import java.time.Period; import java.time.ZoneId; import java.time.ZoneOffset; import java.time.ZonedDateTime; import java.time.format.DateTimeFormatter; import java.time.temporal.TemporalAdjusters; import java.util.Set; import org.junit.Test; public class TestLocalDateTime { //6.ZonedDate、ZonedTime、ZonedDateTime ： 帶時區的時間或日期 @Test public void test7(){ LocalDateTime ldt = LocalDateTime.now(ZoneId.of("Asia/Shanghai")); System.out.println(ldt); ZonedDateTime zdt = ZonedDateTime.now(ZoneId.of("US/Pacific")); System.out.println(zdt); } @Test public void test6(){ Set<String> set = ZoneId.getAvailableZoneIds(); set.forEach(System.out::println); } //5. DateTimeFormatter : 解析和格式化日期或時間 @Test public void test5(){ // DateTimeFormatter dtf = DateTimeFormatter.ISO_LOCAL_DATE; DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss E"); LocalDateTime ldt = LocalDateTime.now(); String strDate = ldt.format(dtf); System.out.println(strDate); LocalDateTime newLdt = ldt.parse(strDate, dtf); System.out.println(newLdt); } //4. TemporalAdjuster : 時間校正器 @Test public void test4(){ LocalDateTime ldt = LocalDateTime.now(); System.out.println(ldt); LocalDateTime ldt2 = ldt.withDayOfMonth(10); System.out.println(ldt2); LocalDateTime ldt3 = ldt.with(TemporalAdjusters.next(DayOfWeek.SUNDAY)); System.out.println(ldt3); //自定義：下一個工作日 LocalDateTime ldt5 = ldt.with((l) -> { LocalDateTime ldt4 = (LocalDateTime) l; DayOfWeek dow = ldt4.getDayOfWeek(); if(dow.equals(DayOfWeek.FRIDAY)){ return ldt4.plusDays(3); }else if(dow.equals(DayOfWeek.SATURDAY)){ return ldt4.plusDays(2); }else{ return ldt4.plusDays(1); } }); System.out.println(ldt5); } //3. //Duration : 用於計算兩個“時間”間隔 //Period : 用於計算兩個“日期”間隔 @Test public void test3(){ Instant ins1 = Instant.now(); System.out.println("--------------------"); try { Thread.sleep(1000); } catch (InterruptedException e) { } Instant ins2 = Instant.now(); System.out.println("所耗費時間為：" + Duration.between(ins1, ins2)); System.out.println("----------------------------------"); LocalDate ld1 = LocalDate.now(); LocalDate ld2 = LocalDate.of(2011, 1, 1); Period pe = Period.between(ld2, ld1); System.out.println(pe.getYears()); System.out.println(pe.getMonths()); System.out.println(pe.getDays()); } //2. Instant : 時間戳。 （使用 Unix 元年 1970年1月1日 00:00:00 所經歷的毫秒值） @Test public void test2(){ Instant ins = Instant.now(); //默認使用 UTC 時區 System.out.println(ins); OffsetDateTime odt = ins.atOffset(ZoneOffset.ofHours(8)); //中國和默認時區差8個小時的時差，（時間偏移量） System.out.println(odt); System.out.println(ins.getNano()); Instant ins2 = Instant.ofEpochSecond(5); System.out.println(ins2); } //1. LocalDate、LocalTime、LocalDateTime @Test public void test1(){ LocalDateTime ldt = LocalDateTime.now(); System.out.println(ldt); LocalDateTime ld2 = LocalDateTime.of(2016, 11, 21, 10, 10, 10); System.out.println(ld2); LocalDateTime ldt3 = ld2.plusYears(20); System.out.println(ldt3); LocalDateTime ldt4 = ld2.minusMonths(2); System.out.println(ldt4); System.out.println(ldt.getYear()); System.out.println(ldt.getMonthValue()); System.out.println(ldt.getDayOfMonth()); System.out.println(ldt.getHour()); System.out.println(ldt.getMinute()); System.out.println(ldt.getSecond()); } }
Java8新特性_日期時間新類 LocalDate、LocalTime、LocalDateTime