Java时间系列(JDK8)--Duration的使用

短命女 2023-09-29 15:34 3阅读 0赞

原文网址：[Java时间系列(JDK8)--Duration的使用\_IT利刃出鞘的博客-CSDN博客][Java_JDK8_--Duration_IT_-CSDN]

## 简介 ##

本文用示例介绍java的Duration的用法。

## Duration和Period ##

**说明**

Duration类通过**年月日时分秒**相结合来描述一个时间量，最高精度是**纳秒**。时间量可以为正也可以为负，比如1天（86400秒0纳秒）、-1天（-86400秒0纳秒）、1年（31556952秒0纳秒）、1毫秒（0秒1000000纳秒）等。

Period类通过**年月日**相结合来描述一个时间量，最高精度是**天**。时间量可以为正也可以为负，例如2年（2年0个月0天）、3个月（0年3个月0天）、4天（0年0月4天）等。

这两个类是不可变的、线程安全的、最终类。都是JDK8新增的。

**Period用法**

见：[Java--Period--使用/实例\_IT利刃出鞘的博客-CSDN博客][Java--Period--_IT_-CSDN]

## 创建方法 ##

### 通过时间单位创建 ###

基于天、时、分、秒、纳秒创建。

ofDays(), ofHours(), ofMillis(), ofMinutes(), ofNanos(), ofSeconds()。例如：

Duration fromDays = Duration.ofDays(1);

### **通过LocalDateTime或LocalTime** ###

通过LocalDateTime或者LocalTime 类，然后使用between获取创建Duration。

LocalDateTime start = LocalDateTime.of(2022, 1, 1, 8, 0, 0);
    LocalDateTime end = LocalDateTime.of(2022, 1, 2, 8, 30, 30);
    
    Duration duration = Duration.between(start, end);

### 通过已有的Duration ###

Duration du1 = Duration.ofHours(10);
    Duration duration = Duration.from(du1);

## 解析方法 ##

### 用法说明 ###

**用法示例**

Duration fromChar1 = Duration.parse("P1DT1H10M10.5S");
    Duration fromChar2 = Duration.parse("PT10M");

**格式说明**

采用ISO-8601时间格式。格式为：PnYnMnDTnHnMnS （n为个数）

例如：P1Y2M10DT2H30M15.03S

*  P：开始标记
 *  1Y：一年
 *  2M：两个月
 *  10D：十天
 *  T：日期和时间的分割标记
 *  2H：两个小时
 *  30M：三十分钟
 *  15S：15.02秒

### 详解 ###

1.  "P", "D", "H", "M" 和 "S"可以是大写或者小写（建议大写）
2.  可以用“-”表示负数

示例大全

"PT20.345S" -- parses as "20.345 seconds"
    "PT15M"     -- parses as "15 minutes" (where a minute is 60 seconds)
    "PT10H"     -- parses as "10 hours" (where an hour is 3600 seconds)
    "P2D"       -- parses as "2 days" (where a day is 24 hours or 86400 seconds)
    "P2DT3H4M"  -- parses as "2 days, 3 hours and 4 minutes"
    "P-6H3M"    -- parses as "-6 hours and +3 minutes"
    "-P6H3M"    -- parses as "-6 hours and -3 minutes"
    "-P-6H+3M"  -- parses as "+6 hours and -3 minutes"

源码：

public final class Duration
            implements TemporalAmount, Comparable<Duration>, Serializable {
    		
    	//其他代码
    	
        //-----------------------------------------------------------------------
        /**
         * Obtains a {@code Duration} from a text string such as {@code PnDTnHnMn.nS}.
         * <p>
         * This will parse a textual representation of a duration, including the
         * string produced by {@code toString()}. The formats accepted are based
         * on the ISO-8601 duration format {@code PnDTnHnMn.nS} with days
         * considered to be exactly 24 hours.
         * <p>
         * The string starts with an optional sign, denoted by the ASCII negative
         * or positive symbol. If negative, the whole period is negated.
         * The ASCII letter "P" is next in upper or lower case.
         * There are then four sections, each consisting of a number and a suffix.
         * The sections have suffixes in ASCII of "D", "H", "M" and "S" for
         * days, hours, minutes and seconds, accepted in upper or lower case.
         * The suffixes must occur in order. The ASCII letter "T" must occur before
         * the first occurrence, if any, of an hour, minute or second section.
         * At least one of the four sections must be present, and if "T" is present
         * there must be at least one section after the "T".
         * The number part of each section must consist of one or more ASCII digits.
         * The number may be prefixed by the ASCII negative or positive symbol.
         * The number of days, hours and minutes must parse to an {@code long}.
         * The number of seconds must parse to an {@code long} with optional fraction.
         * The decimal point may be either a dot or a comma.
         * The fractional part may have from zero to 9 digits.
         * <p>
         * The leading plus/minus sign, and negative values for other units are
         * not part of the ISO-8601 standard.
         * <p>
         * Examples:
         * <pre>
         *    "PT20.345S" -- parses as "20.345 seconds"
         *    "PT15M"     -- parses as "15 minutes" (where a minute is 60 seconds)
         *    "PT10H"     -- parses as "10 hours" (where an hour is 3600 seconds)
         *    "P2D"       -- parses as "2 days" (where a day is 24 hours or 86400 seconds)
         *    "P2DT3H4M"  -- parses as "2 days, 3 hours and 4 minutes"
         *    "P-6H3M"    -- parses as "-6 hours and +3 minutes"
         *    "-P6H3M"    -- parses as "-6 hours and -3 minutes"
         *    "-P-6H+3M"  -- parses as "+6 hours and -3 minutes"
         * </pre>
         *
         * @param text  the text to parse, not null
         * @return the parsed duration, not null
         * @throws DateTimeParseException if the text cannot be parsed to a duration
         */
        public static Duration parse(CharSequence text) {
    		......
    	}
    }

## 比较方法 ##

**比较两个时间的差**

Instant start = Instant.parse("2017-10-03T10:15:30.00Z");
    Instant end = Instant.parse("2017-10-03T10:16:30.00Z");
    
    // start - end         
    Duration duration = Duration.between(start, end);
    
    // 任何一个时间单元为负数，则返回true。true：end早于start
    duration.isNegative();
    
    Duration.between(start, end).getSeconds();
    Duration.between(start, end).getNano();

## 增减方法 ##

**plusX()、minusX()**

X表示days, hours, millis, minutes, nanos 或 seconds

Duration duration = Duration.ofHours(2);
    Duration newDuration = duration.plusSeconds(33);

**plus()/minus()方法**

带TemporalUnit 类型参数进行加减：

Duration duration = Duration.ofHours(2);
    Duration newDuration = duration.plus(33, ChronoUnit.SECONDS);

## 转换单位 ##

可以用toX来转换为其他单位，支持：toDays, toHours, toMinutes, toMillis, toNanos

Duration duration = Duration.ofHours(2);
    
    duration.toDays();     // 0
    duration.toHours();    // 2
    duration.toMinutes();  // 120
    duration.toMillis();   // 7200000
    duration.toNanos();    // 7200000000000

## 取值方法 ##

可以用getX来获得指定位置的值，因为Duration是由秒和纳秒组成，所以只能获得秒和纳秒：

Duration duration = Duration.ofHours(2);
    
    duration.getSeconds();  //7200
    duration.getNano();     //0

[Java_JDK8_--Duration_IT_-CSDN]: https://knife.blog.csdn.net/article/details/124918218
[Java--Period--_IT_-CSDN]: https://knife.blog.csdn.net/article/details/122772818