Java8 时间的各种使用示例 Date转LocalDateTime LocalDateTime转Date 转时间戳

小灰灰 2021-03-30 16:15 1128阅读 1赞

# Java8 时间使用 #

#### 获取当前日期 ####

//2019-06-19
    LocalDate nowLocalDate = LocalDate.now();
    
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    
    //2019-06-19
    String nowString = nowLocalDate.format(formatter);

#### 获取当前时间 ####

//10:03:22.237
    LocalTime localTime = LocalTime.now();
    
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("HH:mm:ss");
    
    //10:03:22
    String stringTime = localTime.format(formatter)

#### 获取当前日期加时间 ####

//2019-06-19T10:06:05.463
    LocalDateTime localDateTime = LocalDateTime.now();
    
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    
    //2019-06-19 10:06:05
    String dateTime = LocalDateTime.now().format(formatter);
    
    //2019-06-19T10:37:07.407
    String dateTime = LocalDateTime.now().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);

#### 自定义时间(LocalDate) ####

//10:09:20
    LocalTime localTime = LocalTime.parse("10:09:20");
    
    //2019-06-19
    LocalDate localDate = LocalDate.parse("2019-06-19");
    
    //2019-06-19T10:09:30
    LocalDateTime localDateTime = LocalDateTime.parse("2019-06-19T10:09:30");

#### 计算两个日期的时间差 ####

//18066 获取从1970年以来的天数：toEpochDay
    long days = LocalDate.now().toEpochDay();
    
    //565 获取两个时间的天数差
    long day = LocalDate.now().toEpochDay() - LocalDate.parse("2017-12-01").toEpochDay();

#### 判断日期的先后，isAfter/isBefore ####

LocalDate date1 = LocalDate.parse("2019-06-19");
    
    LocalDate date2 = LocalDate.parse("2019-06-20");
    //date1是否在date2时间之前
    if (date1.isBefore(date2)) { 
        System.out.println("date1在date2之前");
    }
    //date2是否在date1时间之后
    if (date2.isAfter(date1)) { 
        System.out.println("date2在date1之前");
    }

#### Date和LocalDateTime转换 ####

/** * Date转LocalDateTime * @param date * @return */
    public static LocalDateTime date2LocalDate(Date date) { 
        return date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
    }
    
    /** * Date转LocalDateTime * @param date * @return */
    public static LocalDateTime dateToLocalDate(Date date) { 
        return LocalDateTime.ofInstant(Instant.ofEpochMilli(date.getTime()), ZoneId.systemDefault());
    
    }
    
    /** * LocalDateTime转Date * @param localDateTime * @return */
    public static Date localDate2Date(LocalDateTime localDateTime) { 
        return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
    }
    
    /** * LocalDateTime转Date * @param localDateTime * @return */
    public static Date localDateToDate(LocalDateTime localDateTime) { 
        return new Date(localDateTime.toInstant(ZoneOffset.of("+8")).toEpochMilli());
    }

#### LocalDateTime与时间戳的使用 ####

//获取时间戳秒数
    Long second = LocalDateTime.now().toEpochSecond(ZoneOffset.of("+8"));
    //获取时间戳毫秒数
    Long milliSecond = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
    
    /** * 时间戳转LocalDateTime * @param timestamp * @return */
    public LocalDateTime timestamToLocalDateTime(long timestamp){ 
        return LocalDateTime.ofInstant(Instant.ofEpochMilli(timestamp), ZoneId.systemDefault());
    }
    
    /** * LocalDateTime转时间戳 * @param localDateTime * @return */
    public long localDateTimeToTimestamp(LocalDateTime localDateTime){ 
        return localDateTime.toInstant(ZoneOffset.of("+8")).toEpochMilli();
    }

#### 其它API ####

//2019-06-19T10:25:30.846
    LocalDateTime localDateTime = LocalDateTime.now();
    
    //19 今天是当前月份的第几天
    int dayOfMonth = localDateTime.getDayOfMonth();
    
    //170 今天是今年的第几天
    int dayOfYear = localDateTime.getDayOfYear();
    
    //WEDNESDAY 今天是周几
    DayOfWeek dayOfWeek = localDateTime.getDayOfWeek();
    
    //3 今天是本周第几天
    int dayofWeek = dayOfWeek.getValue();
    
    //2019-06-18T10:25:30.846 获取当前时间前1天时间
    LocalDateTime beforeDateTime = LocalDateTime.now().minusDays(1);
    
    //2019-06-20T10:25:30.846 获取当前时间1天后的时间
    LocalDateTime nextDateTime = LocalDateTime.now().plusDays(1);
    
    //2019-06-19T08:27:30.400 获取当前时间的2小时之前的时间
    LocalDateTime beforeHourTime = LocalDateTime.now().minusHours(2);
    
    //2019-06-19T10:49:20.996 获取当前时间20分钟后的时间
    LocalDateTime afterMinuteTime = LocalDateTime.now().plusMinutes(20);
    
    //false 判断今年是否是闰年
    boolean isLeapYear =  LocalDate.now().isLeapYear();