java--1.8时间API

概述

之前的时间API大部分过时过期的,都是线程不安全的,可变的;

新的API在java.time包下,整体都是不可变线程安全的,较之前的有规律许多;

多线程安全问题

jdk1.7

 @Test
     public void test01() throws Exception{
          //指定时间日期格式
          SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
          Callable<Date> dateCallable = () -> {
               return simpleDateFormat.parse("2016-11-02");
          };

          //线程池
          ExecutorService executorService = Executors.newFixedThreadPool(10);
          //执行10次
          List<Future<Date>> futures=new ArrayList<>();
          for (int i = 0; i < 10; i++) {

               futures.add(executorService.submit(dateCallable));
          }
          futures.forEach(x->{
               try {
                    System.out.println(x.get());
               } catch (InterruptedException e) {
                    e.printStackTrace();
               } catch (ExecutionException e) {
                    e.printStackTrace();
               }
          });
          executorService.shutdown();
     }

异常信息

java.util.concurrent.ExecutionException: java.lang.NumberFormatException: For input string: ""
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at cn.bufanli.time.TimeDemo01.lambda$test01$1(TimeDemo01.java:37)
	at java.util.ArrayList.forEach(ArrayList.java:1257)
	at cn.bufanli.time.TimeDemo01.test01(TimeDemo01.java:35)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Long.parseLong(Long.java:601)
	at java.lang.Long.parseLong(Long.java:631)
	at java.text.DigitList.getLong(DigitList.java:195)
	at java.text.DecimalFormat.parse(DecimalFormat.java:2051)
	at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:2162)
	at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1514)
	at java.text.DateFormat.parse(DateFormat.java:364)
	at cn.bufanli.time.TimeDemo01.lambda$test01$0(TimeDemo01.java:24)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Wed Nov 02 00:00:00 CST 2016
Wed Nov 02 00:00:00 CST 2016
Mon Nov 02 00:00:00 CST 1970
Tue Nov 02 00:00:00 CST 1

jdk1.7--解决方法

加锁:

package cn.bufanli.time;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @author BuShuangLi
 * @date 2019/3/13
 */
public class DateFormaThreadLoca {
     private static final  ThreadLocal<DateFormat> df = new ThreadLocal<DateFormat>(){
          @Override
          protected DateFormat initialValue() {
               return new SimpleDateFormat("yyyy-MM-dd");
          }
     };

     public static Date convet(String source) throws ParseException {
          return df.get().parse(source);
     }
}

测试

     @Test
     public void test02()throws Exception{
          Callable<Date> callable = ()-> DateFormaThreadLoca.convet("2016-12-12");
          ExecutorService executorService = Executors.newFixedThreadPool(10);
          List<Future<Date>> futures = new ArrayList<>();
          for (int i = 0; i < 10; i++) {

               futures.add(executorService.submit(callable));
          }
          for (Future<Date> future : futures) {
               System.out.println(future.get());

          }
          executorService.shutdown();
     }

jdk1.8--解决方法

     /**
      * 1.8
      */
     @Test
     public void test03() {
          DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd");
          //又返回值的线程 lambda表达式
          Callable<LocalDate> callable = () -> LocalDate.parse("2011-12-22", df);
          //创建线程池
          ExecutorService executorService = Executors.newFixedThreadPool(10);

          List< Future<LocalDate>> objects = new ArrayList<>();
          for (int i = 0; i < 10; i++) {
               objects.add(executorService.submit(callable));
          }
          //循环打印集合中的localDate对象
          objects.forEach(x->{
               try {
                    System.out.println(x.get());
               } catch (Exception e) {
                    e.printStackTrace();
               }
          });
     }

新时间日期的API

LocalDate(年月日)、LocalTime(时分秒)、LocalDateTime(年月日时分秒 ) 类的实例是不可变对象,分别表示ISO-8601日历系统的日期、时间、日期和时间.

它们提供了简单的日期或时间,并不包含当前的时间信息.也不包含与时区相关的信息

package cn.bufanli.time;

import org.junit.Test;

import java.time.*;

/**
 * @author BuShuangLi
 * @date 2019/3/13
 */
public class TestLocalDateTime {
     /**
      * 1.LocalDate--> (年月日) LocalTime-->(时分秒) LocalDateTime(年月日时分秒)
      */
     @Test
     public void test01(){
          //获取当前系统时间  控制台: 2019-03-13T15:51:32.969
          System.out.println(LocalDateTime.now());
          //指定年月日分秒 控制台: 2012-12-22T12:33
          LocalDateTime of = LocalDateTime.of(2012, 12, 22, 12, 33);
          System.out.println(of);
          //时间运算  +两年
          LocalDateTime localDateTime = LocalDateTime.now().plusYears(2);
          //输出 2021-03-13T15:56:58.571
          System.out.println(localDateTime);
          //-两个月
          LocalDateTime localDateTime1 = LocalDateTime.now().minusMonths(2);
          //输出 2019-01-13T15:58:58.231
          System.out.println(localDateTime1);
          //单独获取年月日..
          System.out.println(localDateTime1.getYear());
          //月
          System.out.println(localDateTime1.getMonthValue());
          //日
          System.out.println(localDateTime1.getDayOfMonth());
          //小时
          System.out.println(localDateTime1.getHour());

     }

     /**
      * 2.Instant : 时间戳(以Unix 元年 : 1970年1月1日 到某个时间的毫秒值)
      */
     @Test
     public void test02(){
          // 默认获取的是 UTC 时区 输出: 2019-03-13T08:08:18.350Z
          System.out.println(Instant.now());
          //与UTC相差8小时时差
          OffsetDateTime offsetDateTime = Instant.now().atOffset(ZoneOffset.ofHours(8));
          //输出: 2019-03-13T16:10:41.398+08:00
          System.out.println(offsetDateTime);
          //转成毫秒值 1552464779665
          System.out.println(Instant.now().toEpochMilli());

     }
     /**
      * 3.
      *   Duration : 计算两个 时间 之间的间隔的
      *   Period : 计算两个日期之间的间隔
      */
     @Test
     public void test03() throws InterruptedException {
          Instant now1 = Instant.now();
          Thread.sleep(1000);
          Instant now2 = Instant.now();
          //获取毫秒  .toMillis() 其他的都是get..
          System.out.println(Duration.between(now1, now2).toMillis());

          LocalTime now11 = LocalTime.now();
          Thread.sleep(1000);
          LocalTime now22 = LocalTime.now();
          System.out.println(Duration.between(now11, now22).toMillis());


     }
}

日期的操纵

TemporalAdjuster:时间校正器.有时我们需要获取下个周日等操作

TemporalAdjusters: 该类通过静态方法提供了 大量的常用的TemporalAdjuster的实现

代码

 /**
      * TemporalAdjuster 时间教正器
      */
     @Test
     public void test04(){
          LocalDateTime now = LocalDateTime.now();
          System.out.println(now);
          //输出
//          2019-03-13T16:28:02.746
//          2019-03-10T16:28:02.746
          LocalDateTime localDateTime = now.withDayOfMonth(10);
          System.out.println(localDateTime);
          //获取下一个周日日期
          LocalDateTime with = now.with(TemporalAdjusters.next(DayOfWeek.SUNDAY));
          System.out.println(with);
          //自定义 下一个工作日是什么时候
          LocalDateTime with1 = now.with((l) -> {
               LocalDateTime localDateTime1 = (LocalDateTime) l;
               //获取周几
               DayOfWeek dayOfWeek = localDateTime1.getDayOfWeek();
               //判断
               if (dayOfWeek.equals(DayOfWeek.FRIDAY)) {
                    return localDateTime1.plusDays(3);
               } else if (dayOfWeek.equals(DayOfWeek.SATURDAY)) {
                    return localDateTime1.plusDays(2);
               } else {
                    return localDateTime1.plusDays(1);
               }
          });
          //输出下一个工作日的日期
          System.out.println(with1);

     }

DateTimeFormatter: 格式化时间/日期

 /**
      * DateTimeFormatter: 格式化时间/日期
      */
     @Test
     public void test05(){
          DateTimeFormatter isoLocalDate = DateTimeFormatter.ISO_LOCAL_DATE;
          LocalDateTime now = LocalDateTime.now();
          String format = now.format(isoLocalDate);
          System.out.println(format);
          System.out.println("自定义");
          //自定义
          DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
          //日期解析成字符串
          String format2 = now.format(dateTimeFormatter);

          //字符串解析成日期LocalDateTime.parse(时间字符串,解析格式)
          LocalDateTime parse = LocalDateTime.parse(format2, dateTimeFormatter);
          System.out.println(parse);


     }