java8 日期操作

柔光的暖阳◎ 2022-12-23 03:17 211阅读 0赞

java8 日期操作

*  SimpleDateFormat存在线程安全问题，解析错误：
 *  Caused by: java.lang.NumberFormatException: multiple points
 *  
 *  java8 日期操作新API：LocalDate,LocalTime,LocalDateTime类的实例都是不可变对象
 *  DateTimeFormatter：时间格式化
 *  TemporalAdjuster时间校正器
 *  时区ZonedDate,ZonedTime,ZonedDateTime

import com.google.common.util.concurrent.ThreadFactoryBuilder;
    import lombok.SneakyThrows;
    import org.junit.Test;
    
    import java.text.DateFormat;
    import java.text.SimpleDateFormat;
    import java.time.*;
    import java.time.format.DateTimeFormatter;
    import java.time.temporal.TemporalAdjusters;
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    import java.util.Set;
    import java.util.concurrent.*;
    
    /** * SimpleDateFormat存在线程安全问题，解析错误： * Caused by: java.lang.NumberFormatException: multiple points * * java8 日期操作新API：LocalDate,LocalTime,LocalDateTime类的实例都是不可变对象 * DateTimeFormatter：时间格式化 * TemporalAdjuster时间校正器 * 时区ZonedDate,ZonedTime,ZonedDateTime * * @author zrj * @version V1.0 * @since 2020/11/21 **/
    public class SimpleDateTest { 
    
        // 定义线程池
        private static ThreadFactory namedThreadFactory = new ThreadFactoryBuilder()
                .setNameFormat( "sdf-pool-%d" ).build();
        private static ExecutorService pool = new ThreadPoolExecutor( 10, 50, 0L
                , TimeUnit.SECONDS, new LinkedBlockingQueue<>( 1024 )
                , namedThreadFactory, new ThreadPoolExecutor.AbortPolicy() );
    
        /** * 定义DateFormat */
        private static final ThreadLocal<DateFormat> df = ThreadLocal.withInitial( () -> new SimpleDateFormat( "yyyyMMdd" ) );
    
        /** * 新老对比，线程安全问题 */
        @Test
        public void dateFormatTest() { 
            SimpleDateFormat sdf = new SimpleDateFormat( "yyyyMMdd" );
    
            //1. simpleDateFormat 线程不安全情况，会抛出异常
            Callable<Date> task1 = () -> sdf.parse( "20201121" );
            List<Future<Date>> futureList1 = new ArrayList<>( 10 );
    
            //2. threadLocal枷锁 线程安全情况，不会抛出异常
            Callable<Date> task2 = () -> df.get().parse( "20201121" );
            List<Future<Date>> futureList2 = new ArrayList<>( 10 );
    
            //3.Java1.8以后dateTimeFormatter,线程安全
            DateTimeFormatter dtf = DateTimeFormatter.ofPattern( "yyyyMMdd" );
            Callable<LocalDate> task3 = () -> LocalDate.parse( "20201121", dtf );
            List<Future<LocalDate>> futureList = new ArrayList<>( 10 );
    
            for (int i = 0; i < 10; i++) { 
                futureList.add( pool.submit( task3 ) );
            }
    
            // 遍历结果
            futureList.forEach( future -> { 
                try { 
                    System.out.println( future.get() );
                } catch (Exception e) { 
                    e.printStackTrace();
                }
            } );
            // 关闭线程池
            pool.shutdown();
        }
    
        /** * 1.8新API使用 * LocalDate,LocalTime,LocalDateTime类的实例都是不可变对象 * 表示日期，时间，日期和时间 */
        @SneakyThrows
        @Test
        public void localDateTimeTest() { 
            // LocalDateTime ->2020-11-21T18:30:14.177
            LocalDateTime ldt = LocalDateTime.now();
            System.out.println( "当前时间：" + ldt );
    
            // LocalDateTime ->2020-11-21T18:31
            LocalDateTime localDateTime = LocalDateTime.of( 2020, 11, 21, 18, 31 );
            System.out.println( "当前时间：" + localDateTime );
    
            // 简单运算, 加年，加月，加日，小时也可以
            System.out.println( "---------相加---------" );
            System.out.println( ldt.plusYears( 2 ) );
            System.out.println( ldt.plusMonths( 3 ) );
            System.out.println( ldt.plusDays( 5 ) );
            System.out.println( ldt.plusHours( 3 ) );
    
            // 相减
            System.out.println( "---------相减---------" );
            System.out.println( ldt.minusYears( 2 ) );
            System.out.println( ldt.minusMonths( 3 ) );
            System.out.println( ldt.minusDays( 5 ) );
            System.out.println( ldt.minusHours( 3 ) );
    
            // 获取本地时间
            System.out.println( "---------获取本地时间---------" );
            System.out.println( ldt.getYear() );
            System.out.println( ldt.getMonth() );
            System.out.println( ldt.getDayOfMonth() );
            System.out.println( ldt.getHour() );
            System.out.println( ldt.getMinute() );
            System.out.println( ldt.getSecond() );
    
            // Instance 时间戳（以Unix元年：1970年1月1日00:00:00到某个时间的毫秒值）
            System.out.println( "---------获取本地时间---------" );
            // 获取的不是系统时间，是UTC时区：2020-11-21T10:48:39.169Z
            Instant instant = Instant.now();
            System.out.println( instant );
    
            //偏移量运算:2020-11-21T18:48:39.169+08:00
            OffsetDateTime offsetDateTime = instant.atOffset( ZoneOffset.ofHours( 8 ) );
            System.out.println( offsetDateTime );
    
            // 获取毫秒:1605955719169
            long epochMilli = instant.toEpochMilli();
            System.out.println( epochMilli );
    
            // 计算时间间隔
            System.out.println( "---------计算时间间隔-Instant--------" );
            Instant instant1 = Instant.now();
            Thread.sleep( 1000 );
            Instant instant2 = Instant.now();
            Duration duration = Duration.between( instant1, instant2 );
            System.out.println( duration.toMillis() );
    
            System.out.println( "---------计算时间间隔-LocalDateTime---" );
            LocalDateTime ldt1 = LocalDateTime.now();
            Thread.sleep( 1000 );
            LocalDateTime ldt2 = LocalDateTime.now();
            Duration duration1 = Duration.between( instant1, instant2 );
            System.out.println( duration1.toMillis() );
    
            System.out.println( "---------计算日期间隔-LocalDateTime---" );
            LocalDate localDate1 = LocalDate.now();
            LocalDate localDate2 = LocalDate.of( 2020, 12, 11 );
            Period period = Period.between( localDate1, localDate2 );
            System.out.println( period.getYears() );
            System.out.println( period.getMonths() );
            System.out.println( period.getDays() );
    
        }
    
        /** * TemporalAdjuster时间校正器 * TemporalAdjusters时间校正器工具类，提供大量静态方法 * 例如将日期调整到下个周日 */
        @Test
        public void temporalAdjusterTest() { 
    
            //2020-11-21T19:01:17.364
            System.out.println( "---------当前日期---------" );
            LocalDateTime ldt = LocalDateTime.now();
            System.out.println( ldt );
    
            //2020-11-10T19:01:17.364
            System.out.println( "---------当前日期10天前的日期---------" );
            LocalDateTime localDateTime = ldt.withDayOfMonth( 10 );
            System.out.println( localDateTime );
    
            //下个周日是几号
            System.out.println( "---------下个周日是几号---------" );
            LocalDateTime dateTimeWith = ldt.with( TemporalAdjusters.next( DayOfWeek.SUNDAY ) );
            System.out.println( dateTimeWith );
    
            //自定义：下一个工作日
            System.out.println( "---------自定义：下一个工作日---------" );
            LocalDateTime localWith = ldt.with( (L) -> { 
                LocalDateTime ldt2 = (LocalDateTime) L;
                DayOfWeek dayOfWeek = ldt2.getDayOfWeek();
                if (dayOfWeek.equals( DayOfWeek.FRIDAY )) { 
                    return ldt2.plusDays( 3 );
                } else if (dayOfWeek.equals( DayOfWeek.SATURDAY )) { 
                    return ldt2.plusDays( 2 );
                } else { 
                    return ldt2.plusDays( 1 );
                }
            } );
            System.out.println( localWith );
        }
    
        /** * DateTimeFormatter：时间格式化 */
        @Test
        public void DateTimeFormatterTest() { 
    
            // ISO默认：2020-11-21T19:18:57.259
            DateTimeFormatter dtf = DateTimeFormatter.ISO_DATE_TIME;
            LocalDateTime ldt = LocalDateTime.now();
    
            String format = ldt.format( dtf );
            System.out.println( format );
    
            // 自定义格式
            DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern( "yyyy年MM月dd日 HH:mm:ss" );
            String format1 = ldt.format( dtf2 );
            System.out.println( format1 );
    
        }
    
    
        /** * 时区ZonedDate,ZonedTime,ZonedDateTime */
        @Test
        public void zonedDateTimeTest() { 
            // 查看时区
            System.out.println( "---------查看时区---------" );
            Set<String> availableZoneIds = ZoneId.getAvailableZoneIds();
            availableZoneIds.forEach( System.out::println );
    
            //获取指定时区的时间：Shanghai：2020-11-21T19:35:24.579
            System.out.println( "---------获取指定时区的时间---------" );
            LocalDateTime now = LocalDateTime.now( ZoneId.of( "Asia/Shanghai" ) );
            LocalDateTime now1 = LocalDateTime.now( ZoneId.of( "Japan" ) );
            System.out.println( "Shanghai：" + now );
            System.out.println( "Japan：" + now1 );
    
            //带偏移量的时区时间:2020-11-21T19:35:24.580+09:00[Japan]
            System.out.println( "---------带偏移量的时区时间---------" );
            LocalDateTime now2 = LocalDateTime.now( ZoneId.of( "Asia/Shanghai" ) );
            ZonedDateTime japan = now2.atZone( ZoneId.of( "Japan" ) );
            System.out.println( japan );
    
        }
        
    }