API: https://api.dart.dev/stable/2.10.3/dart-core/DateTime-class.html

constructor

DateTime

通过 DateTime 实例进行解析, 可以接收8个参数，第一个是年份必填，剩余的是选填，如下：

  1. /**
  2.  *  DateTime(int year,
  3.  *     [int month = 1,
  4.  *     int day = 1,
  5.  *     int hour = 0,
  6.  *     int minute = 0,
  7.  *     int second = 0,
  8.  *     int millisecond = 0,
  9.  *     int microsecond = 0])
  10.  */
  12. // 默认获取的是本地时间
  13. print(DateTime(2020, 11, 04, 9, 30)); //2020-11-04 09:30:00.000
  14. print(DateTime(2020, 11, 04, 9, 30).toLocal()); //2020-11-04 09:30:00.000

now 获取当前时间

  1. var s1 = DateTime.now();  //等同于：var s1 = new DateTime.now();
  2. print(s1); //2020-11-04 15:16:07.579148
  3. print(s1.runtimeType); //DateTime

utc 获取utc时间

  1. print(DateTime.utc(2020, 11, 04, 9, 30)); //2020-11-04 09:30:00.000Z
  2. print(DateTime.utc(2020, 11, 04, 9, 30).toLocal()); //2020-11-04 17:30:00.000

fromMillisecondsSinceEpoch、fromMicrosecondsSinceEpoch

  1. var s1 = DateTime(2020, 11, 04, 09, 20, 40, 432, 789);
  2. print(s1); //2020-11-04 09:20:40.432789
  4. var millisecondsSinceEpoch = s1.millisecondsSinceEpoch;
  5. var microsecondsSinceEpoch = s1.microsecondsSinceEpoch;
  7. print(millisecondsSinceEpoch);  //1604452840432     获取13位毫秒数
  8. print(microsecondsSinceEpoch);  //1604452840432789    获取16位微秒数
  10. print(DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch)); 
  11. //2020-11-04 09:20:40.432
  12. print(DateTime.fromMicrosecondsSinceEpoch(microsecondsSinceEpoch)); 
  13. //2020-11-04 09:20:40.432789

TimeOfDay

  1. print(TimeOfDay.now()); //TimeOfDay(17:36)
  2. print(TimeOfDay.fromDateTime(DateTime.now())); //TimeOfDay(17:36)
  3. print(TimeOfDay(hour: 15, minute: 04)); //TimeOfDay(15:04)
  4. print(TimeOfDay.now().format(context)); //5:36 PM
  5. print(TimeOfDay.now().toString().substring(10, 15)); //17:36

Static methods 类的静态方法

parse 解析日期

https://api.dart.dev/stable/2.10.3/dart-core/DateTime/parse.html
参数接收一个字符串, 能够被解析的有以下格式：

  • "2012-02-27"
  • "2012-02-27 13:27:00"
  • "2012-02-27 13:27:00.123456789z"
  • "2012-02-27 13:27:00,123456789z"
  • "20120227 13:27:00"
  • "20120227T132700"
  • "20120227"
  • "+20120227"
  • "2012-02-27T14Z"
  • "2012-02-27T14+00:00"
  • "-123450101 00:00:00 Z": in the year -12345.
  • "2002-02-27T14:00:00-0500": Same as "2002-02-27T19:00:00Z" ```dart

print(DateTime.parse(‘2020-11-04 09:30:04’)); //2020-11-04 09:30:04.000 print(DateTime.parse(‘2020-11-04 09:30:04+0800’)); //2020-11-04 01:30:04.000Z

  2. <a name="wzFFY"></a>
  3. ## tryParse parse的语法糖
  4. 如果接收的参数无法被解析那么不会抛出异常，而是返回 null 。
  6. 内部实现原理：
  7. ```dart
  8. try {
  9.   return parse(formattedString);
  10. } on FormatException {
  11.   return null;
  12. }

属性

  1. var s1 = DateTime.now();
  2. print(s1); //2020-11-04 15:30:59.621947
  4. print(s1.year); //2020    年
  5. print(s1.month); //11    月（1-12，与js不一样）
  6. print(s1.day); //4    天 （1-31）
  7. print(s1.hour); //15    时    （0-23）
  8. print(s1.minute); //30    分    （0-59）
  9. print(s1.second); //59    秒    （0-59）
  10. print(s1.millisecond); //621    毫秒    （0-999）
  11. print(s1.millisecondsSinceEpoch); //1604475059621    获取13位毫秒时间戳
  12. print(s1.microsecond); //947    微秒    （0-999）
  13. print(s1.microsecondsSinceEpoch); //1604475059621947    获取16位微秒时间戳
  15. print(s1.weekday); //3  星期几（1-7）
  16. print(s1.timeZoneName); //'中国标准时间'    时区名字
  17. print(s1.timeZoneOffset); //8:00:00.000000    时区的偏移时差（北京时区是东八区，领先UTC八个小时）
  19. print(s1.isUtc); //false    是否是UTC时间
  20. print(s1.hashCode); //904666416   hash码

方法

add 添加时间

通过添加时间来改变原始的 DateTime，参数接收的是 Duration 类型。

  1. var s1 = DateTime(2020, 11, 04, 09, 20, 40);
  2. print(s1); //2020-11-04 09:20:40.000
  4. // 加5分钟
  5. print(s1.add(new Duration(minutes: 5))); //2020-11-04 09:25:40.000
  6. print(s1.add(new Duration(minutes: -5))); //2020-11-04 09:15:40.000
  8. // 加10小时
  9. print(s1.add(new Duration(hours: 10))); //2020-11-04 19:20:40.000
  10. print(s1.add(new Duration(hours: -10))); //2020-11-03 23:20:40.000

subtract 减少时间

add的反向操作。

  1. var s1 = DateTime(2020, 11, 04, 09, 20, 40);  
  2. print(s1); //2020-11-04 09:20:40.000
  4. // 减 5分钟
  5. print(s1.subtract(new Duration(minutes: 5))); //2020-11-04 09:15:40.000
  6. print(s1.subtract(new Duration(minutes: -5))); //2020-11-04 09:25:40.000
  8. // 减 10小时
  9. print(s1.subtract(new Duration(hours: 10))); //2020-11-03 23:20:40.000
  10. print(s1.subtract(new Duration(hours: -10))); //2020-11-04 19:20:40.000

isBefore、isAfter、compareTo、isAtSameMomentAs 比较时间

  • **isBefore** 检查一个 DateTime 是否在另一个 DateTime 之前
  • **isAfter** 检查一个 DateTime 是否在另一个 DateTime 之后
  • **compareTo** 判断2个 DateTime 是否相等，如果相等则返回 0 否则 -1
  • **isAtSameMomentAs** 如果此事件与other同时发生，则返回true ```dart var s1 = DateTime(2020, 11, 11, 6, 10, 20); var s2 = DateTime(2020, 11, 12, 10, 20, 10);

print(s1.isBefore(s2)); //true 时间是否早于参数 print(s1.isAfter(s2)); //false 时间是否晚于参数

print(s1.compareTo(s2)); //-1 时间早于参数，返回-1； print(s1.compareTo(s1)); //0 时间相同，返回0； print(s2.compareTo(s1)); //1 时间晚于参数，返回1；

// s4、s4是同一时间，但是是不同的时区 var s3 = DateTime.utc(2020, 11, 04, 9, 30); var s4 = s3.toLocal();

// 比较时间是否相同 print(s3 == s4); //false print(s3.isAtSameMomentAs(s4)); //true

  2. <a name="U45T3"></a>
  3. ## difference 时间差
  4. ```dart
  5. var s1 = DateTime(2020, 11, 11, 6, 10, 20);
  6. var s2 = DateTime(2020, 11, 12, 10, 20, 10);
  7. var diff = s1.difference(s2);
  8. print(diff); //-28:09:50.000000  s1比s2早了 28:09:50.000000
  9. print([diff.inDays, diff.inHours, diff.inMinutes]); //[-1, -28, -1689] 相差的天数、小时数、分钟数

toString、toIso8601String、toLocal、toUtc

  • toString 要把一个 DateTime 转换成时间可以使用 toString 方法
  • toIso8601String 转换成 ISO 8601 。 toIso8601String-API 。
  • toLocal 在本地时区返回此DateTime值
  • toUtc 在UTC时区中返回此DateTime值 ```dart var s1 = DateTime(2020, 11, 04, 09, 20, 40, 432, 789);

print(s1); //2020-11-04 09:20:40.432789 print(s1.toString()); //2020-11-04 09:20:40.432789 print(s1.toIso8601String()); //2020-11-04T09:20:40.432789 print(s1.toLocal()); //2020-11-04 09:20:40.432789 print(s1.toUtc()); //2020-11-04 01:20:40.432789Z

  3. <a name="frM0i"></a>
  4. # 常用封装方法
  5. <a name="XIQhC"></a>
  6. ## 补零
  7. ```dart
  8. formatNumber(n, [m = 2]) {
  9.   return n.toString().padLeft(m, '0');
  10. }
  12. print('${formatNumber(1)} -- ${formatNumber(12)} -- ${formatNumber(123)}'); 
  13. //01 -- 12 -- 123
  14. print('${formatNumber(1, 3)} -- ${formatNumber(12, 3)} -- ${formatNumber(123, 3)}'); 
  15. //001 -- 012 -- 123
  17. String _digits(int value, int length) {
  18.   String ret = '$value';
  19.   if (ret.length < length) {
  20.     ret = '0' * (length - ret.length) + ret;
  21.   }
  22.   return ret;
  23. }
  24. print(_digits(2, 2)); //02
  25. print(_digits(2, 3)); //002
  26. print(_digits(21, 2)); //21
  27. print(_digits(21, 3)); //021

获取简单时间

  1. var s1 = DateTime(2020, 11, 04, 09, 20, 40, 432, 789);
  2. print(s1); //2020-11-04 09:20:40.432789
  3. var millisecondsSinceEpoch = s1.millisecondsSinceEpoch;
  4. print(millisecondsSinceEpoch); //1604452840432
  6. formatNumber(n, [m = 2]) {
  7.   return n.toString().padLeft(m, '0');
  8. }
  10. formateTimeSimple(time, [hasTime = false, sep = "-"]) {
  11.   var date = DateTime.fromMillisecondsSinceEpoch(time);
  12.   var year = date.year;
  13.   var month = date.month;
  14.   var day = date.day;
  15.   var hour = date.hour;
  16.   var minute = date.minute;
  18.   if (hasTime) {
  19.     return '${[year, month, day].map(formatNumber).join(sep)} ${[hour, minute].map(formatNumber).join(":")}';
  20.   } else {
  21.     return '${[year, month, day].map(formatNumber).join(sep)}';
  22.   }
  23. }
  25. print(formateTimeSimple(millisecondsSinceEpoch));    //2020-11-04
  26. print(formateTimeSimple(millisecondsSinceEpoch, true));    //2020-11-04 09:20
  27. print(formateTimeSimple(millisecondsSinceEpoch, true, '.'));    //2020.11.04 09:20

库 date_format

https://pub.dev/packages/date_format

  1. import 'package:date_format/date_format.dart';
  3. void main() {
  4.   var date = DateTime(1989, 02, 11, 15, 04, 10, 765);
  5.   // 1989年 => yyyy 1989;  yy 89
  6.   // 02月   => mm 02; m 2;  MM February;  M Feb
  7.   // 11日   => dd 11; d 11;
  9.   // 15时   => HH 15; H 15; hh 03;  h 3
  10.   // 04分   => nn 04; n 4
  11.   // 10时   => ss 10; s 10
  12.   // 765秒  => SSS 765
  14.   // 周几   => DD Saturday;  D Sat
  15.   // 时区   => z +0800； Z 中国标准时间
  16.   // 上下午 => am (下午15点 -> PM；早上5点 -> AM)
  18.   //w 2（本月的第几周）；WW 06（本年的第几周） 注意： 周二算是每周的第一天
  20.   print(formatDate(date, ['yyyy', '-', 'mm', '-', 'DD'])); //1989-02-11
  21.   print(formatDate(date, [yyyy, '-', mm, '-', DD])); //1989-02-11
  22.   print(formatDate(date, [yy, '-', m, '-', D])); //89-2-11
  23.   print(formatDate(date, [HH, ':', nn, ':', ss])); //15:04:10
  24.   print(formatDate(date, [H, ':', n, ':', s])); //15:4:10
  25.   print(formatDate(date, [H, ':', n, ':', s, z])); //15:4:10+0800
  26.   print(formatDate(date, [w, '--', WW])); //2--06
  27. }